diff --git a/src/cmd/compile/internal/base/debug.go b/src/cmd/compile/internal/base/debug.go
index 08ccef3..420ad13 100644
--- a/src/cmd/compile/internal/base/debug.go
+++ b/src/cmd/compile/internal/base/debug.go
@@ -41,10 +41,6 @@
 	LoopVarHash           string `help:"for debugging changes in loop behavior. Overrides experiment and loopvar flag."`
 	LocationLists         int    `help:"print information about DWARF location list creation"`
 	MaxShapeLen           int    `help:"hash shape names longer than this threshold (default 500)" concurrent:"ok"`
-	MergeLocals           int    `help:"merge together non-interfering local stack slots" concurrent:"ok"`
-	MergeLocalsDumpFunc   string `help:"dump specified func in merge locals"`
-	MergeLocalsHash       string `help:"hash value for debugging stack slot merging of local variables" concurrent:"ok"`
-	MergeLocalsTrace      int    `help:"trace debug output for locals merging"`
 	Nil                   int    `help:"print information about nil checks"`
 	NoOpenDefer           int    `help:"disable open-coded defers" concurrent:"ok"`
 	NoRefName             int    `help:"do not include referenced symbol names in object file" concurrent:"ok"`
diff --git a/src/cmd/compile/internal/base/flag.go b/src/cmd/compile/internal/base/flag.go
index 1ee3337..5b3c3ad 100644
--- a/src/cmd/compile/internal/base/flag.go
+++ b/src/cmd/compile/internal/base/flag.go
@@ -184,7 +184,6 @@
 	Debug.SyncFrames = -1 // disable sync markers by default
 	Debug.ZeroCopy = 1
 	Debug.RangeFuncCheck = 1
-	Debug.MergeLocals = 1
 
 	Debug.Checkptr = -1 // so we can tell whether it is set explicitly
 
@@ -261,9 +260,6 @@
 	if Debug.PGOHash != "" {
 		PGOHash = NewHashDebug("pgohash", Debug.PGOHash, nil)
 	}
-	if Debug.MergeLocalsHash != "" {
-		MergeLocalsHash = NewHashDebug("mergelocals", Debug.MergeLocalsHash, nil)
-	}
 
 	if Flag.MSan && !platform.MSanSupported(buildcfg.GOOS, buildcfg.GOARCH) {
 		log.Fatalf("%s/%s does not support -msan", buildcfg.GOOS, buildcfg.GOARCH)
diff --git a/src/cmd/compile/internal/base/hashdebug.go b/src/cmd/compile/internal/base/hashdebug.go
index 7a5cc42..4e36c8d 100644
--- a/src/cmd/compile/internal/base/hashdebug.go
+++ b/src/cmd/compile/internal/base/hashdebug.go
@@ -53,10 +53,9 @@
 // The default compiler-debugging HashDebug, for "-d=gossahash=..."
 var hashDebug *HashDebug
 
-var FmaHash *HashDebug         // for debugging fused-multiply-add floating point changes
-var LoopVarHash *HashDebug     // for debugging shared/private loop variable changes
-var PGOHash *HashDebug         // for debugging PGO optimization decisions
-var MergeLocalsHash *HashDebug // for debugging local stack slot merging changes
+var FmaHash *HashDebug     // for debugging fused-multiply-add floating point changes
+var LoopVarHash *HashDebug // for debugging shared/private loop variable changes
+var PGOHash *HashDebug     // for debugging PGO optimization decisions
 
 // DebugHashMatchPkgFunc reports whether debug variable Gossahash
 //
diff --git a/src/cmd/compile/internal/ir/name.go b/src/cmd/compile/internal/ir/name.go
index 1ce6e43..7581586 100644
--- a/src/cmd/compile/internal/ir/name.go
+++ b/src/cmd/compile/internal/ir/name.go
@@ -194,7 +194,6 @@
 	nameLibfuzzer8BitCounter     // if PEXTERN should be assigned to __sancov_cntrs section
 	nameCoverageAuxVar           // instrumentation counter var or pkg ID for cmd/cover
 	nameAlias                    // is type name an alias
-	nameNonMergeable             // not a candidate for stack slot merging
 )
 
 func (n *Name) Readonly() bool                 { return n.flags&nameReadonly != 0 }
@@ -210,7 +209,6 @@
 func (n *Name) OpenDeferSlot() bool            { return n.flags&nameOpenDeferSlot != 0 }
 func (n *Name) Libfuzzer8BitCounter() bool     { return n.flags&nameLibfuzzer8BitCounter != 0 }
 func (n *Name) CoverageAuxVar() bool           { return n.flags&nameCoverageAuxVar != 0 }
-func (n *Name) NonMergeable() bool             { return n.flags&nameNonMergeable != 0 }
 
 func (n *Name) setReadonly(b bool)                 { n.flags.set(nameReadonly, b) }
 func (n *Name) SetNeedzero(b bool)                 { n.flags.set(nameNeedzero, b) }
@@ -225,7 +223,6 @@
 func (n *Name) SetOpenDeferSlot(b bool)            { n.flags.set(nameOpenDeferSlot, b) }
 func (n *Name) SetLibfuzzer8BitCounter(b bool)     { n.flags.set(nameLibfuzzer8BitCounter, b) }
 func (n *Name) SetCoverageAuxVar(b bool)           { n.flags.set(nameCoverageAuxVar, b) }
-func (n *Name) SetNonMergeable(b bool)             { n.flags.set(nameNonMergeable, b) }
 
 // OnStack reports whether variable n may reside on the stack.
 func (n *Name) OnStack() bool {
diff --git a/src/cmd/compile/internal/liveness/mergelocals.go b/src/cmd/compile/internal/liveness/mergelocals.go
deleted file mode 100644
index a1342ef..0000000
--- a/src/cmd/compile/internal/liveness/mergelocals.go
+++ /dev/null
@@ -1,691 +0,0 @@
-// Copyright 2024 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package liveness
-
-import (
-	"cmd/compile/internal/base"
-	"cmd/compile/internal/bitvec"
-	"cmd/compile/internal/ir"
-	"cmd/compile/internal/reflectdata"
-	"cmd/compile/internal/ssa"
-	"cmd/internal/obj"
-	"cmd/internal/src"
-	"fmt"
-	"os"
-	"path/filepath"
-	"sort"
-	"strings"
-)
-
-// MergeLocalsState encapsulates information about which AUTO
-// (stack-allocated) variables within a function can be safely
-// merged/overlapped, e.g. share a stack slot with some other auto).
-// An instance of MergeLocalsState is produced by MergeLocals() below
-// and then consumed in ssagen.AllocFrame. The map 'partition' contains
-// entries of the form <N,SL> where N is an *ir.Name and SL is a slice
-// holding the indices (within 'vars') of other variables that share the
-// same slot. For example, if a function contains five variables where
-// v1/v2/v3 are safe to overlap and v4/v5 are safe to overlap, the
-// MergeLocalsState content might look like
-//
-//	vars: [v1, v2, v3, v4, v5]
-//	partition: v1 -> [1, 0, 2], v2 -> [1, 0, 2], v3 -> [1, 0, 2]
-//	           v4 -> [3, 4], v5 -> [3, 4]
-//
-// A nil MergeLocalsState indicates that no local variables meet the
-// necessary criteria for overlap.
-type MergeLocalsState struct {
-	// contains auto vars that participate in overlapping
-	vars []*ir.Name
-	// maps auto variable to overlap partition
-	partition map[*ir.Name][]int
-}
-
-// candRegion is a sub-range (start, end) corresponding to an interval
-// [st,en] within the list of candidate variables.
-type candRegion struct {
-	st, en int
-}
-
-// MergeLocals analyzes the specified ssa function f to determine which
-// of its auto variables can safely share the same stack slot, returning
-// a state object that describes how the overlap should be done.
-func MergeLocals(fn *ir.Func, f *ssa.Func) *MergeLocalsState {
-	cands, idx, regions := collectMergeCandidates(fn)
-	if len(regions) == 0 {
-		return nil
-	}
-	lv := newliveness(fn, f, cands, idx, 0)
-
-	// If we have a local variable such as "r2" below that's written
-	// but then not read, something like:
-	//
-	//      vardef r1
-	//      r1.x = ...
-	//      vardef r2
-	//      r2.x = 0
-	//      r2.y = ...
-	//      <call foo>
-	//      // no subsequent use of r2
-	//      ... = r1.x
-	//
-	// then for the purpose of calculating stack maps at the call, we
-	// can ignore "r2" completely during liveness analysis for stack
-	// maps, however for stack slock merging we most definitely want
-	// to treat the writes as "uses".
-	lv.conservativeWrites = true
-
-	lv.prologue()
-	lv.solve()
-	cs := &cstate{
-		fn:        fn,
-		ibuilders: make([]IntervalsBuilder, len(cands)),
-	}
-	computeIntervals(lv, cs)
-	rv := performMerging(lv, cs, regions)
-	if err := rv.check(); err != nil {
-		base.FatalfAt(fn.Pos(), "invalid mergelocals state: %v", err)
-	}
-	return rv
-}
-
-// Subsumed returns whether variable n is subsumed, e.g. appears
-// in an overlap position but is not the leader in that partition.
-func (mls *MergeLocalsState) Subsumed(n *ir.Name) bool {
-	if sl, ok := mls.partition[n]; ok && mls.vars[sl[0]] != n {
-		return true
-	}
-	return false
-}
-
-// IsLeader returns whether a variable n is the leader (first element)
-// in a sharing partition.
-func (mls *MergeLocalsState) IsLeader(n *ir.Name) bool {
-	if sl, ok := mls.partition[n]; ok && mls.vars[sl[0]] == n {
-		return true
-	}
-	return false
-}
-
-// Leader returns the leader variable for subsumed var n.
-func (mls *MergeLocalsState) Leader(n *ir.Name) *ir.Name {
-	if sl, ok := mls.partition[n]; ok {
-		if mls.vars[sl[0]] == n {
-			panic("variable is not subsumed")
-		}
-		return mls.vars[sl[0]]
-	}
-	panic("not a merge candidate")
-}
-
-// Followers writes a list of the followers for leader n into the slice tmp.
-func (mls *MergeLocalsState) Followers(n *ir.Name, tmp []*ir.Name) []*ir.Name {
-	tmp = tmp[:0]
-	sl, ok := mls.partition[n]
-	if !ok {
-		panic("no entry for leader")
-	}
-	if mls.vars[sl[0]] != n {
-		panic("followers invoked on subsumed var")
-	}
-	for _, k := range sl[1:] {
-		tmp = append(tmp, mls.vars[k])
-	}
-	sort.SliceStable(tmp, func(i, j int) bool {
-		return tmp[i].Sym().Name < tmp[j].Sym().Name
-	})
-	return tmp
-}
-
-// EstSavings returns the estimated reduction in stack size for
-// the given merge locals state.
-func (mls *MergeLocalsState) EstSavings() int {
-	tot := 0
-	for n := range mls.partition {
-		if mls.Subsumed(n) {
-			tot += int(n.Type().Size())
-		}
-	}
-	return tot
-}
-
-// check tests for various inconsistencies and problems in mls,
-// returning an error if any problems are found.
-func (mls *MergeLocalsState) check() error {
-	if mls == nil {
-		return nil
-	}
-	used := make(map[int]bool)
-	seenv := make(map[*ir.Name]int)
-	for ii, v := range mls.vars {
-		if prev, ok := seenv[v]; ok {
-			return fmt.Errorf("duplicate var %q in vslots: %d and %d\n",
-				v.Sym().Name, ii, prev)
-		}
-		seenv[v] = ii
-	}
-	for k, sl := range mls.partition {
-		// length of slice value needs to be more than 1
-		if len(sl) < 2 {
-			return fmt.Errorf("k=%q v=%+v slice len %d invalid",
-				k.Sym().Name, sl, len(sl))
-		}
-		// values in the slice need to be var indices
-		for i, v := range sl {
-			if v < 0 || v > len(mls.vars)-1 {
-				return fmt.Errorf("k=%q v=+%v slpos %d vslot %d out of range of m.v", k.Sym().Name, sl, i, v)
-			}
-		}
-	}
-	for k, sl := range mls.partition {
-		foundk := false
-		for i, v := range sl {
-			vv := mls.vars[v]
-			if i == 0 {
-				if !mls.IsLeader(vv) {
-					return fmt.Errorf("k=%s v=+%v slpos 0 vslot %d IsLeader(%q) is false should be true", k.Sym().Name, sl, v, vv.Sym().Name)
-				}
-			} else {
-				if !mls.Subsumed(vv) {
-					return fmt.Errorf("k=%s v=+%v slpos %d vslot %d Subsumed(%q) is false should be true", k.Sym().Name, sl, i, v, vv.Sym().Name)
-				}
-				if mls.Leader(vv) != mls.vars[sl[0]] {
-					return fmt.Errorf("k=%s v=+%v slpos %d vslot %d Leader(%q) got %v want %v", k.Sym().Name, sl, i, v, vv.Sym().Name, mls.Leader(vv), mls.vars[sl[0]])
-				}
-			}
-			if vv == k {
-				foundk = true
-				if used[v] {
-					return fmt.Errorf("k=%s v=+%v val slice used violation at slpos %d vslot %d", k.Sym().Name, sl, i, v)
-				}
-				used[v] = true
-			}
-		}
-		if !foundk {
-			return fmt.Errorf("k=%s v=+%v slice value missing k", k.Sym().Name, sl)
-		}
-	}
-	for i := range used {
-		if !used[i] {
-			return fmt.Errorf("pos %d var %q unused", i, mls.vars[i])
-		}
-	}
-	return nil
-}
-
-func (mls *MergeLocalsState) String() string {
-	var leaders []*ir.Name
-	for n, sl := range mls.partition {
-		if n == mls.vars[sl[0]] {
-			leaders = append(leaders, n)
-		}
-	}
-	sort.Slice(leaders, func(i, j int) bool {
-		return leaders[i].Sym().Name < leaders[j].Sym().Name
-	})
-	var sb strings.Builder
-	for _, n := range leaders {
-		sb.WriteString(n.Sym().Name + ":")
-		sl := mls.partition[n]
-		for _, k := range sl[1:] {
-			n := mls.vars[k]
-			sb.WriteString(" " + n.Sym().Name)
-		}
-		sb.WriteString("\n")
-	}
-	return sb.String()
-}
-
-// collectMergeCandidates visits all of the AUTO vars declared in
-// function fn and returns a list of candidate variables for merging /
-// overlapping. Return values are: 1) a slice of ir.Name's
-// corresponding to the candidates, 2) a map that maps ir.Name to slot
-// in the slice, and 3) a slice containing regions (start/end pairs)
-// corresponding to variables that could be overlapped provided that
-// their lifetimes are disjoint.
-func collectMergeCandidates(fn *ir.Func) ([]*ir.Name, map[*ir.Name]int32, []candRegion) {
-	m := make(map[*ir.Name]int32)
-	var cands []*ir.Name
-	var regions []candRegion
-
-	// Collect up the available set of appropriate AUTOs in the
-	// function as a first step.
-	for _, n := range fn.Dcl {
-		if !n.Used() {
-			continue
-		}
-		if !ssa.IsMergeCandidate(n) {
-			continue
-		}
-		cands = append(cands, n)
-	}
-	if len(cands) < 2 {
-		return nil, nil, nil
-	}
-
-	// Sort by pointerness, size, and then name.
-	sort.SliceStable(cands, func(i, j int) bool {
-		ci, cj := cands[i], cands[j]
-		ihp, jhp := 0, 0
-		var ilsym, jlsym *obj.LSym
-		if ci.Type().HasPointers() {
-			ihp = 1
-			ilsym, _, _ = reflectdata.GCSym(ci.Type())
-		}
-		if cj.Type().HasPointers() {
-			jhp = 1
-			jlsym, _, _ = reflectdata.GCSym(cj.Type())
-		}
-		if ihp != jhp {
-			return ihp < jhp
-		}
-		if ci.Type().Size() != cj.Type().Size() {
-			return ci.Type().Size() < cj.Type().Size()
-		}
-		if ihp != 0 && jhp != 0 && ilsym != jlsym {
-			// FIXME: find less clunky way to do this
-			return fmt.Sprintf("%v", ilsym) < fmt.Sprintf("%v", jlsym)
-		}
-		if ci.Sym().Name != cj.Sym().Name {
-			return ci.Sym().Name < cj.Sym().Name
-		}
-		return fmt.Sprintf("%v", ci.Pos()) < fmt.Sprintf("%v", ci.Pos())
-	})
-
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "=-= raw cand list for func %v:\n", fn)
-		for i := range cands {
-			dumpCand(cands[i], i)
-		}
-	}
-
-	// Now generate a pruned candidate list-- we only want to return a
-	// non-empty list if there is some possibility of overlapping two
-	// vars.
-	var pruned []*ir.Name
-	st := 0
-	for {
-		en := nextRegion(cands, st)
-		if en == -1 {
-			break
-		}
-		if st == en {
-			// region has just one element, we can skip it
-			st++
-			continue
-		}
-		pst := len(pruned)
-		pen := pst + (en - st)
-		if base.Debug.MergeLocalsTrace > 1 {
-			fmt.Fprintf(os.Stderr, "=-= add part %d -> %d\n", pst, pen)
-		}
-
-		// non-empty region, add to pruned
-		pruned = append(pruned, cands[st:en+1]...)
-		regions = append(regions, candRegion{st: pst, en: pen})
-		st = en + 1
-	}
-	if len(pruned) < 2 {
-		return nil, nil, nil
-	}
-	for i, n := range pruned {
-		m[n] = int32(i)
-	}
-
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "=-= pruned candidate list for func %v:\n", fn)
-		for i := range pruned {
-			dumpCand(pruned[i], i)
-		}
-	}
-	return pruned, m, regions
-}
-
-// nextRegion starts at location idx and walks forward in the cands
-// slice looking for variables that are "compatible" (overlappable)
-// with the variable at position idx; it returns the end of the new
-// region (range of compatible variables starting at idx).
-func nextRegion(cands []*ir.Name, idx int) int {
-	n := len(cands)
-	if idx >= n {
-		return -1
-	}
-	c0 := cands[idx]
-	hp0 := c0.Type().HasPointers()
-	for j := idx + 1; j < n; j++ {
-		cj := cands[j]
-		hpj := cj.Type().HasPointers()
-		ok := true
-		if hp0 {
-			if !hpj || c0.Type().Size() != cj.Type().Size() {
-				return j - 1
-			}
-			// GC shape must match if both types have pointers.
-			gcsym0, _, _ := reflectdata.GCSym(c0.Type())
-			gcsymj, _, _ := reflectdata.GCSym(cj.Type())
-			if gcsym0 != gcsymj {
-				return j - 1
-			}
-		} else {
-			// If no pointers, match size only.
-			if !ok || hp0 != hpj || c0.Type().Size() != cj.Type().Size() {
-				return j - 1
-			}
-		}
-	}
-	return n - 1
-}
-
-type cstate struct {
-	fn        *ir.Func
-	ibuilders []IntervalsBuilder
-}
-
-// mergeVisitRegion tries to perform overlapping of variables with a
-// given subrange of cands described by st and en (indices into our
-// candidate var list), where the variables within this range have
-// already been determined to be compatible with respect to type,
-// size, etc. Overlapping is done in a a greedy fashion: we select the
-// first element in the st->en range, then walk the rest of the
-// elements adding in vars whose lifetimes don't overlap with the
-// first element, then repeat the process until we run out of work to do.
-func (mls *MergeLocalsState) mergeVisitRegion(lv *liveness, ivs []Intervals, st, en int) {
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "=-= mergeVisitRegion(st=%d, en=%d)\n", st, en)
-	}
-	n := en - st + 1
-	used := bitvec.New(int32(n))
-
-	nxt := func(slot int) int {
-		for c := slot - st; c < n; c++ {
-			if used.Get(int32(c)) {
-				continue
-			}
-			return c + st
-		}
-		return -1
-	}
-
-	navail := n
-	cands := lv.vars
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "  =-= navail = %d\n", navail)
-	}
-	for navail >= 2 {
-		leader := nxt(st)
-		used.Set(int32(leader - st))
-		navail--
-
-		if base.Debug.MergeLocalsTrace > 1 {
-			fmt.Fprintf(os.Stderr, "  =-= begin leader %d used=%s\n", leader,
-				used.String())
-		}
-		elems := []int{leader}
-		lints := ivs[leader]
-
-		for succ := nxt(leader + 1); succ != -1; succ = nxt(succ + 1) {
-
-			// Skip if de-selected by merge locals hash.
-			if base.Debug.MergeLocalsHash != "" {
-				if !base.MergeLocalsHash.MatchPosWithInfo(cands[succ].Pos(), "mergelocals", nil) {
-					continue
-				}
-			}
-			// Skip if already used.
-			if used.Get(int32(succ - st)) {
-				continue
-			}
-			if base.Debug.MergeLocalsTrace > 1 {
-				fmt.Fprintf(os.Stderr, "  =-= overlap of %d[%v] {%s} with %d[%v] {%s} is: %v\n", leader, cands[leader], lints.String(), succ, cands[succ], ivs[succ].String(), lints.Overlaps(ivs[succ]))
-			}
-
-			// Can we overlap leader with this var?
-			if lints.Overlaps(ivs[succ]) {
-				continue
-			} else {
-				// Add to overlap set.
-				elems = append(elems, succ)
-				lints = lints.Merge(ivs[succ])
-			}
-		}
-		if len(elems) > 1 {
-			// We found some things to overlap with leader. Add the
-			// candidate elements to "vars" and update "partition".
-			off := len(mls.vars)
-			sl := make([]int, len(elems))
-			for i, candslot := range elems {
-				sl[i] = off + i
-				mls.vars = append(mls.vars, cands[candslot])
-				mls.partition[cands[candslot]] = sl
-			}
-			navail -= (len(elems) - 1)
-			for i := range elems {
-				used.Set(int32(elems[i] - st))
-			}
-			if base.Debug.MergeLocalsTrace > 1 {
-				fmt.Fprintf(os.Stderr, "=-= overlapping %+v:\n", sl)
-				for i := range sl {
-					dumpCand(mls.vars[sl[i]], sl[i])
-				}
-				for i, v := range elems {
-					fmt.Fprintf(os.Stderr, "=-= %d: sl=%d %s\n", i, v, ivs[v])
-				}
-			}
-		}
-	}
-}
-
-// performMerging carries out variable merging within each of the
-// candidate ranges in regions, returning a state object
-// that describes the variable overlaps.
-func performMerging(lv *liveness, cs *cstate, regions []candRegion) *MergeLocalsState {
-	cands := lv.vars
-	mls := &MergeLocalsState{
-		partition: make(map[*ir.Name][]int),
-	}
-
-	// Finish intervals construction.
-	ivs := make([]Intervals, len(cands))
-	for i := range cands {
-		var err error
-		ivs[i], err = cs.ibuilders[i].Finish()
-		if err != nil {
-			ninstr := 0
-			if base.Debug.MergeLocalsTrace != 0 {
-				iidx := 0
-				for k := 0; k < len(lv.f.Blocks); k++ {
-					b := lv.f.Blocks[k]
-					fmt.Fprintf(os.Stderr, "\n")
-					for _, v := range b.Values {
-						fmt.Fprintf(os.Stderr, " b%d %d: %s\n", k, iidx, v.LongString())
-						iidx++
-						ninstr++
-					}
-				}
-			}
-			base.FatalfAt(cands[i].Pos(), "interval construct error for var %q in func %q (%d instrs): %v", cands[i].Sym().Name, ir.FuncName(cs.fn), ninstr, err)
-			return nil
-		}
-	}
-
-	// Dump state before attempting overlap.
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "=-= cands live before overlap:\n")
-		for i := range cands {
-			c := cands[i]
-			fmt.Fprintf(os.Stderr, "%d: %v sz=%d ivs=%s\n",
-				i, c.Sym().Name, c.Type().Size(), ivs[i].String())
-		}
-		fmt.Fprintf(os.Stderr, "=-= regions (%d): ", len(regions))
-		for _, cr := range regions {
-			fmt.Fprintf(os.Stderr, " [%d,%d]", cr.st, cr.en)
-		}
-		fmt.Fprintf(os.Stderr, "\n")
-	}
-
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "=-= len(regions) = %d\n", len(regions))
-	}
-
-	// Apply a greedy merge/overlap strategy within each region
-	// of compatible variables.
-	for _, cr := range regions {
-		mls.mergeVisitRegion(lv, ivs, cr.st, cr.en)
-	}
-	if len(mls.vars) == 0 {
-		return nil
-	}
-	return mls
-}
-
-// computeIntervals performs a backwards sweep over the instructions
-// of the function we're compiling, building up an Intervals object
-// for each candidate variable by looking for upwards exposed uses
-// and kills.
-func computeIntervals(lv *liveness, cs *cstate) {
-	nvars := int32(len(lv.vars))
-	liveout := bitvec.New(nvars)
-
-	if base.Debug.MergeLocalsDumpFunc != "" &&
-		strings.HasSuffix(fmt.Sprintf("%v", cs.fn), base.Debug.MergeLocalsDumpFunc) {
-		fmt.Fprintf(os.Stderr, "=-= mergelocalsdumpfunc %v:\n", cs.fn)
-		ii := 0
-		for k, b := range lv.f.Blocks {
-			fmt.Fprintf(os.Stderr, "b%d:\n", k)
-			for _, v := range b.Values {
-				pos := base.Ctxt.PosTable.Pos(v.Pos)
-				fmt.Fprintf(os.Stderr, "=-= %d L%d|C%d %s\n", ii, pos.RelLine(), pos.RelCol(), v.LongString())
-				ii++
-			}
-		}
-	}
-
-	// Count instructions.
-	ninstr := 0
-	for _, b := range lv.f.Blocks {
-		ninstr += len(b.Values)
-	}
-	// current instruction index during backwards walk
-	iidx := ninstr - 1
-
-	// Make a backwards pass over all blocks
-	for k := len(lv.f.Blocks) - 1; k >= 0; k-- {
-		b := lv.f.Blocks[k]
-		be := lv.blockEffects(b)
-
-		if base.Debug.MergeLocalsTrace > 2 {
-			fmt.Fprintf(os.Stderr, "=-= liveout from tail of b%d: ", k)
-			for j := range lv.vars {
-				if be.liveout.Get(int32(j)) {
-					fmt.Fprintf(os.Stderr, " %q", lv.vars[j].Sym().Name)
-				}
-			}
-			fmt.Fprintf(os.Stderr, "\n")
-		}
-
-		// Take into account effects taking place at end of this basic
-		// block by comparing our current live set with liveout for
-		// the block. If a given var was not live before and is now
-		// becoming live we need to mark this transition with a
-		// builder "Live" call; similarly if a var was live before and
-		// is now no longer live, we need a "Kill" call.
-		for j := range lv.vars {
-			isLive := liveout.Get(int32(j))
-			blockLiveOut := be.liveout.Get(int32(j))
-			if isLive {
-				if !blockLiveOut {
-					if base.Debug.MergeLocalsTrace > 2 {
-						fmt.Fprintf(os.Stderr, "=+= at instr %d block boundary kill of %v\n", iidx, lv.vars[j])
-					}
-					cs.ibuilders[j].Kill(iidx)
-				}
-			} else if blockLiveOut {
-				if base.Debug.MergeLocalsTrace > 2 {
-					fmt.Fprintf(os.Stderr, "=+= at block-end instr %d %v becomes live\n",
-						iidx, lv.vars[j])
-				}
-				cs.ibuilders[j].Live(iidx)
-			}
-		}
-
-		// Set our working "currently live" set to the previously
-		// computed live out set for the block.
-		liveout.Copy(be.liveout)
-
-		// Now walk backwards through this block.
-		for i := len(b.Values) - 1; i >= 0; i-- {
-			v := b.Values[i]
-
-			if base.Debug.MergeLocalsTrace > 2 {
-				fmt.Fprintf(os.Stderr, "=-= b%d instr %d: %s\n", k, iidx, v.LongString())
-			}
-
-			// Update liveness based on what we see happening in this
-			// instruction.
-			pos, e := lv.valueEffects(v)
-			becomeslive := e&uevar != 0
-			iskilled := e&varkill != 0
-			if becomeslive && iskilled {
-				// we do not ever expect to see both a kill and an
-				// upwards exposed use given our size constraints.
-				panic("should never happen")
-			}
-			if iskilled && liveout.Get(pos) {
-				cs.ibuilders[pos].Kill(iidx)
-				liveout.Unset(pos)
-				if base.Debug.MergeLocalsTrace > 2 {
-					fmt.Fprintf(os.Stderr, "=+= at instr %d kill of %v\n",
-						iidx, lv.vars[pos])
-				}
-			} else if becomeslive && !liveout.Get(pos) {
-				cs.ibuilders[pos].Live(iidx)
-				liveout.Set(pos)
-				if base.Debug.MergeLocalsTrace > 2 {
-					fmt.Fprintf(os.Stderr, "=+= at instr %d upwards-exposed use of %v\n",
-						iidx, lv.vars[pos])
-				}
-			}
-			iidx--
-		}
-
-		if b == lv.f.Entry {
-			for j, v := range lv.vars {
-				if liveout.Get(int32(j)) {
-					lv.f.Fatalf("%v %L recorded as live on entry",
-						lv.fn.Nname, v)
-				}
-			}
-		}
-	}
-	if iidx != -1 {
-		panic("iidx underflow")
-	}
-}
-
-func dumpCand(c *ir.Name, i int) {
-	fmtFullPos := func(p src.XPos) string {
-		var sb strings.Builder
-		sep := ""
-		base.Ctxt.AllPos(p, func(pos src.Pos) {
-			fmt.Fprintf(&sb, sep)
-			sep = "|"
-			file := filepath.Base(pos.Filename())
-			fmt.Fprintf(&sb, "%s:%d:%d", file, pos.Line(), pos.Col())
-		})
-		return sb.String()
-	}
-	fmt.Fprintf(os.Stderr, " %d: %s %q sz=%d hp=%v t=%v\n",
-		i, fmtFullPos(c.Pos()), c.Sym().Name, c.Type().Size(),
-		c.Type().HasPointers(), c.Type())
-}
-
-// for unit testing only.
-func MakeMergeLocalsState(partition map[*ir.Name][]int, vars []*ir.Name) (*MergeLocalsState, error) {
-	mls := &MergeLocalsState{partition: partition, vars: vars}
-	if err := mls.check(); err != nil {
-		return nil, err
-	}
-	return mls, nil
-}
diff --git a/src/cmd/compile/internal/liveness/plive.go b/src/cmd/compile/internal/liveness/plive.go
index ab1a7df..e4dbfa9 100644
--- a/src/cmd/compile/internal/liveness/plive.go
+++ b/src/cmd/compile/internal/liveness/plive.go
@@ -143,11 +143,6 @@
 
 	doClobber     bool // Whether to clobber dead stack slots in this function.
 	noClobberArgs bool // Do not clobber function arguments
-
-	// treat "dead" writes as equivalent to reads during the analysis;
-	// used only during liveness analysis for stack slot merging (doesn't
-	// make sense for stackmap analysis).
-	conservativeWrites bool
 }
 
 // Map maps from *ssa.Value to StackMapIndex.
@@ -317,12 +312,8 @@
 	if e&(ssa.SymRead|ssa.SymAddr) != 0 {
 		effect |= uevar
 	}
-	if e&ssa.SymWrite != 0 {
-		if !isfat(n.Type()) || v.Op == ssa.OpVarDef {
-			effect |= varkill
-		} else if lv.conservativeWrites {
-			effect |= uevar
-		}
+	if e&ssa.SymWrite != 0 && (!isfat(n.Type()) || v.Op == ssa.OpVarDef) {
+		effect |= varkill
 	}
 
 	if effect == 0 {
@@ -459,11 +450,6 @@
 // this argument and the in arguments are always assumed live. The vars
 // argument is a slice of *Nodes.
 func (lv *liveness) pointerMap(liveout bitvec.BitVec, vars []*ir.Name, args, locals bitvec.BitVec) {
-	var slotsSeen map[int64]*ir.Name
-	checkForDuplicateSlots := base.Debug.MergeLocals != 0
-	if checkForDuplicateSlots {
-		slotsSeen = make(map[int64]*ir.Name)
-	}
 	for i := int32(0); ; i++ {
 		i = liveout.Next(i)
 		if i < 0 {
@@ -482,12 +468,6 @@
 			fallthrough // PPARAMOUT in registers acts memory-allocates like an AUTO
 		case ir.PAUTO:
 			typebits.Set(node.Type(), node.FrameOffset()+lv.stkptrsize, locals)
-			if checkForDuplicateSlots {
-				if prev, ok := slotsSeen[node.FrameOffset()]; ok {
-					base.FatalfAt(node.Pos(), "two vars live at pointerMap generation: %q and %q", prev.Sym().Name, node.Sym().Name)
-				}
-				slotsSeen[node.FrameOffset()] = node
-			}
 		}
 	}
 }
diff --git a/src/cmd/compile/internal/ssa/check.go b/src/cmd/compile/internal/ssa/check.go
index cb6788c..bbfdace 100644
--- a/src/cmd/compile/internal/ssa/check.go
+++ b/src/cmd/compile/internal/ssa/check.go
@@ -314,9 +314,8 @@
 					f.Fatalf("bad arg 1 type to %s: want integer, have %s", v.Op, v.Args[1].LongString())
 				}
 			case OpVarDef:
-				n := v.Aux.(*ir.Name)
-				if !n.Type().HasPointers() && !IsMergeCandidate(n) {
-					f.Fatalf("vardef must be merge candidate or have pointer type %s", v.Aux.(*ir.Name).Type().String())
+				if !v.Aux.(*ir.Name).Type().HasPointers() {
+					f.Fatalf("vardef must have pointer type %s", v.Aux.(*ir.Name).Type().String())
 				}
 			case OpNilCheck:
 				// nil checks have pointer type before scheduling, and
diff --git a/src/cmd/compile/internal/ssa/func.go b/src/cmd/compile/internal/ssa/func.go
index 38b459a..031d94f 100644
--- a/src/cmd/compile/internal/ssa/func.go
+++ b/src/cmd/compile/internal/ssa/func.go
@@ -838,25 +838,5 @@
 
 // NewLocal returns a new anonymous local variable of the given type.
 func (f *Func) NewLocal(pos src.XPos, typ *types.Type) *ir.Name {
-	nn := typecheck.TempAt(pos, f.fe.Func(), typ) // Note: adds new auto to fn.Dcl list
-	nn.SetNonMergeable(true)
-	return nn
-}
-
-// IsMergeCandidate returns true if variable n could participate in
-// stack slot merging. For now we're restricting the set to things to
-// items larger than what CanSSA would allow (approximateky, we disallow things
-// marked as open defer slots so as to avoid complicating liveness
-// analysis.
-func IsMergeCandidate(n *ir.Name) bool {
-	if base.Debug.MergeLocals == 0 ||
-		base.Flag.N != 0 ||
-		n.Class != ir.PAUTO ||
-		n.Type().Size() <= int64(3*types.PtrSize) ||
-		n.Addrtaken() ||
-		n.NonMergeable() ||
-		n.OpenDeferSlot() {
-		return false
-	}
-	return true
+	return typecheck.TempAt(pos, f.fe.Func(), typ) // Note: adds new auto to fn.Dcl list
 }
diff --git a/src/cmd/compile/internal/ssagen/pgen.go b/src/cmd/compile/internal/ssagen/pgen.go
index d0045e7..c3d9ec3 100644
--- a/src/cmd/compile/internal/ssagen/pgen.go
+++ b/src/cmd/compile/internal/ssagen/pgen.go
@@ -13,7 +13,6 @@
 
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
-	"cmd/compile/internal/liveness"
 	"cmd/compile/internal/objw"
 	"cmd/compile/internal/ssa"
 	"cmd/compile/internal/types"
@@ -152,18 +151,6 @@
 		}
 	}
 
-	var mls *liveness.MergeLocalsState
-	if base.Debug.MergeLocals != 0 {
-		mls = liveness.MergeLocals(fn, f)
-		if base.Debug.MergeLocalsTrace == 1 && mls != nil {
-			fmt.Fprintf(os.Stderr, "%s: %d bytes of stack space saved via stack slot merging\n", ir.FuncName(fn), mls.EstSavings())
-			if base.Debug.MergeLocalsTrace > 1 {
-				fmt.Fprintf(os.Stderr, "=-= merge locals state for %v:\n%v",
-					fn, mls)
-			}
-		}
-	}
-
 	// Use sort.SliceStable instead of sort.Slice so stack layout (and thus
 	// compiler output) is less sensitive to frontend changes that
 	// introduce or remove unused variables.
@@ -171,22 +158,6 @@
 		return cmpstackvarlt(fn.Dcl[i], fn.Dcl[j])
 	})
 
-	if base.Debug.MergeLocalsTrace > 1 && mls != nil {
-		fmt.Fprintf(os.Stderr, "=-= sorted DCL for %v:\n", fn)
-		for i, v := range fn.Dcl {
-			if !ssa.IsMergeCandidate(v) {
-				continue
-			}
-			fmt.Fprintf(os.Stderr, " %d: %q isleader=%v subsumed=%v used=%v\n", i, v.Sym().Name, mls.IsLeader(v), mls.Subsumed(v), v.Used())
-
-		}
-	}
-
-	var leaders map[*ir.Name]int64
-	if mls != nil {
-		leaders = make(map[*ir.Name]int64)
-	}
-
 	// Reassign stack offsets of the locals that are used.
 	lastHasPtr := false
 	for i, n := range fn.Dcl {
@@ -194,14 +165,12 @@
 			// i.e., stack assign if AUTO, or if PARAMOUT in registers (which has no predefined spill locations)
 			continue
 		}
-		if mls != nil && mls.Subsumed(n) {
-			continue
-		}
 		if !n.Used() {
 			fn.DebugInfo.(*ssa.FuncDebug).OptDcl = fn.Dcl[i:]
 			fn.Dcl = fn.Dcl[:i]
 			break
 		}
+
 		types.CalcSize(n.Type())
 		w := n.Type().Size()
 		if w >= types.MaxWidth || w < 0 {
@@ -226,42 +195,6 @@
 			lastHasPtr = false
 		}
 		n.SetFrameOffset(-s.stksize)
-		if mls != nil && mls.IsLeader(n) {
-			leaders[n] = -s.stksize
-		}
-	}
-
-	if mls != nil {
-		followers := []*ir.Name{}
-		newdcl := make([]*ir.Name, 0, len(fn.Dcl))
-		for i := 0; i < len(fn.Dcl); i++ {
-			n := fn.Dcl[i]
-			if mls.Subsumed(n) {
-				continue
-			}
-			newdcl = append(newdcl, n)
-			if off, ok := leaders[n]; ok {
-				followers = mls.Followers(n, followers)
-				for _, f := range followers {
-					// Set the stack offset for each follower to be
-					// the same as the leader.
-					f.SetFrameOffset(off)
-				}
-				// position followers immediately after leader
-				newdcl = append(newdcl, followers...)
-			}
-		}
-		fn.Dcl = newdcl
-	}
-
-	if base.Debug.MergeLocalsTrace > 1 {
-		fmt.Fprintf(os.Stderr, "=-= stack layout for %v:\n", fn)
-		for i, v := range fn.Dcl {
-			if v.Op() != ir.ONAME || (v.Class != ir.PAUTO && !(v.Class == ir.PPARAMOUT && v.IsOutputParamInRegisters())) {
-				continue
-			}
-			fmt.Fprintf(os.Stderr, " %d: %q frameoff %d used=%v\n", i, v.Sym().Name, v.FrameOffset(), v.Used())
-		}
 	}
 
 	s.stksize = types.RoundUp(s.stksize, s.stkalign)
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index f27e3ac..37d6165 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -633,7 +633,7 @@
 		if typ := n.Type(); ssa.CanSSA(typ) {
 			s.assign(n, s.zeroVal(typ), false, 0)
 		} else {
-			if typ.HasPointers() || ssa.IsMergeCandidate(n) {
+			if typ.HasPointers() {
 				s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
 			}
 			s.zero(n.Type(), s.decladdrs[n])
@@ -3942,7 +3942,7 @@
 
 	// If this assignment clobbers an entire local variable, then emit
 	// OpVarDef so liveness analysis knows the variable is redefined.
-	if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && (t.HasPointers() || ssa.IsMergeCandidate(base)) {
+	if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && t.HasPointers() {
 		s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
 	}
 
@@ -5382,8 +5382,7 @@
 		}
 		// Make a defer struct on the stack.
 		t := deferstruct()
-		n, addr := s.temp(n.Pos(), t)
-		n.SetNonMergeable(true)
+		_, addr := s.temp(n.Pos(), t)
 		s.store(closure.Type,
 			s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(deferStructFnField), addr),
 			closure)
@@ -6887,7 +6886,7 @@
 // temp allocates a temp of type t at position pos
 func (s *state) temp(pos src.XPos, t *types.Type) (*ir.Name, *ssa.Value) {
 	tmp := typecheck.TempAt(pos, s.curfn, t)
-	if t.HasPointers() || (ssa.IsMergeCandidate(tmp) && t != deferstruct()) {
+	if t.HasPointers() {
 		s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, tmp, s.mem())
 	}
 	addr := s.addr(tmp)
diff --git a/src/cmd/compile/internal/test/mergelocals_test.go b/src/cmd/compile/internal/test/mergelocals_test.go
deleted file mode 100644
index f070197..0000000
--- a/src/cmd/compile/internal/test/mergelocals_test.go
+++ /dev/null
@@ -1,184 +0,0 @@
-// Copyright 2024 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package test
-
-import (
-	"cmd/compile/internal/ir"
-	"cmd/compile/internal/liveness"
-	"cmd/compile/internal/typecheck"
-	"cmd/compile/internal/types"
-	"cmd/internal/src"
-	"internal/testenv"
-	"path/filepath"
-	"slices"
-	"sort"
-	"strings"
-	"testing"
-)
-
-func TestMergeLocalState(t *testing.T) {
-	mkiv := func(name string) *ir.Name {
-		i32 := types.Types[types.TINT32]
-		s := typecheck.Lookup(name)
-		v := ir.NewNameAt(src.NoXPos, s, i32)
-		return v
-	}
-	v1 := mkiv("v1")
-	v2 := mkiv("v2")
-	v3 := mkiv("v3")
-
-	testcases := []struct {
-		vars      []*ir.Name
-		partition map[*ir.Name][]int
-		experr    bool
-	}{
-		{
-			vars: []*ir.Name{v1, v2, v3},
-			partition: map[*ir.Name][]int{
-				v1: []int{0, 1, 2},
-				v2: []int{0, 1, 2},
-				v3: []int{0, 1, 2},
-			},
-			experr: false,
-		},
-		{
-			// invalid mls.v slot -1
-			vars: []*ir.Name{v1, v2, v3},
-			partition: map[*ir.Name][]int{
-				v1: []int{-1, 0},
-				v2: []int{0, 1, 2},
-				v3: []int{0, 1, 2},
-			},
-			experr: true,
-		},
-		{
-			// duplicate var in v
-			vars: []*ir.Name{v1, v2, v2},
-			partition: map[*ir.Name][]int{
-				v1: []int{0, 1, 2},
-				v2: []int{0, 1, 2},
-				v3: []int{0, 1, 2},
-			},
-			experr: true,
-		},
-		{
-			// single element in partition
-			vars: []*ir.Name{v1, v2, v3},
-			partition: map[*ir.Name][]int{
-				v1: []int{0},
-				v2: []int{0, 1, 2},
-				v3: []int{0, 1, 2},
-			},
-			experr: true,
-		},
-		{
-			// missing element 2
-			vars: []*ir.Name{v1, v2, v3},
-			partition: map[*ir.Name][]int{
-				v1: []int{0, 1},
-				v2: []int{0, 1},
-				v3: []int{0, 1},
-			},
-			experr: true,
-		},
-		{
-			// partitions disagree for v1 vs v2
-			vars: []*ir.Name{v1, v2, v3},
-			partition: map[*ir.Name][]int{
-				v1: []int{0, 1, 2},
-				v2: []int{1, 0, 2},
-				v3: []int{0, 1, 2},
-			},
-			experr: true,
-		},
-	}
-
-	for k, testcase := range testcases {
-		mls, err := liveness.MakeMergeLocalsState(testcase.partition, testcase.vars)
-		t.Logf("tc %d err is %v\n", k, err)
-		if testcase.experr && err == nil {
-			t.Fatalf("tc:%d missing error mls %v", k, mls)
-		} else if !testcase.experr && err != nil {
-			t.Fatalf("tc:%d unexpected error mls %v", k, err)
-		}
-		if mls != nil {
-			t.Logf("tc %d: mls: %v\n", k, mls.String())
-		}
-	}
-}
-
-func TestMergeLocalsIntegration(t *testing.T) {
-	testenv.MustHaveGoBuild(t)
-
-	// This test does a build of a specific canned package to
-	// check whether merging of stack slots is taking place.
-	// The idea is to do the compile with a trace option turned
-	// on and then pick up on the frame offsets of specific
-	// variables.
-	//
-	// Stack slot merging is a greedy algorithm, and there can
-	// be many possible ways to overlap a given set of candidate
-	// variables, all of them legal. Rather than locking down
-	// a specific set of overlappings or frame offsets, this
-	// tests just verifies that there is one clump of 3 vars that
-	// get overlapped, then another clump of 2 that share the same
-	// frame offset.
-	//
-	// The expected output blob we're interested in looks like this:
-	//
-	// =-= stack layout for ABC:
-	//  2: "p1" frameoff -8200 used=true
-	//  3: "xp3" frameoff -8200 used=true
-	//  4: "xp4" frameoff -8200 used=true
-	//  5: "p2" frameoff -16400 used=true
-	//  6: "s" frameoff -24592 used=true
-	//  7: "v1" frameoff -32792 used=true
-	//  8: "v3" frameoff -32792 used=true
-	//  9: "v2" frameoff -40992 used=true
-	//
-	tmpdir := t.TempDir()
-	src := filepath.Join("testdata", "mergelocals", "integration.go")
-	obj := filepath.Join(tmpdir, "p.a")
-	out, err := testenv.Command(t, testenv.GoToolPath(t), "tool", "compile", "-p=p", "-c", "1", "-o", obj, "-d=mergelocalstrace=2,mergelocals=1", src).CombinedOutput()
-	if err != nil {
-		t.Fatalf("failed to compile: %v\n%s", err, out)
-	}
-	vars := make(map[string]string)
-	lines := strings.Split(string(out), "\n")
-	prolog := true
-	varsAtFrameOffset := make(map[string]int)
-	for _, line := range lines {
-		if line == "=-= stack layout for ABC:" {
-			prolog = false
-			continue
-		} else if prolog || line == "" {
-			continue
-		}
-		fields := strings.Fields(line)
-		if len(fields) != 5 {
-			t.Fatalf("bad trace output line: %s", line)
-		}
-		vname := fields[1]
-		frameoff := fields[3]
-		varsAtFrameOffset[frameoff] = varsAtFrameOffset[frameoff] + 1
-		vars[vname] = frameoff
-	}
-	wantvnum := 8
-	gotvnum := len(vars)
-	if wantvnum != gotvnum {
-		t.Fatalf("expected trace output on %d vars got %d\n", wantvnum, gotvnum)
-	}
-
-	// We expect one clump of 3, another clump of 2, and the rest singletons.
-	expected := []int{1, 1, 1, 2, 3}
-	got := []int{}
-	for _, v := range varsAtFrameOffset {
-		got = append(got, v)
-	}
-	sort.Ints(got)
-	if !slices.Equal(got, expected) {
-		t.Fatalf("expected variable clumps %+v not equal to what we got: %+v", expected, got)
-	}
-}
diff --git a/src/cmd/compile/internal/test/testdata/mergelocals/integration.go b/src/cmd/compile/internal/test/testdata/mergelocals/integration.go
deleted file mode 100644
index d640c6f..0000000
--- a/src/cmd/compile/internal/test/testdata/mergelocals/integration.go
+++ /dev/null
@@ -1,83 +0,0 @@
-// Copyright 2024 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package p
-
-// This type and the following one will share the same GC shape and size.
-type Pointery struct {
-	p *Pointery
-	x [1024]int
-}
-
-type Pointery2 struct {
-	p *Pointery2
-	x [1024]int
-}
-
-// This type and the following one will have the same size.
-type Vanilla struct {
-	np uintptr
-	x  [1024]int
-}
-
-type Vanilla2 struct {
-	np uintptr
-	x  [1023]int
-	y  int
-}
-
-type Single struct {
-	np uintptr
-	x  [1023]int
-}
-
-func ABC(i, j int) int {
-	r := 0
-
-	// here v1 interferes with v2 but could be overlapped with v3.
-	// we can also overlap v1 with v3.
-	var v1 Vanilla
-	if i < 101 {
-		var v2 Vanilla
-		v1.x[i] = j
-		r += v1.x[j]
-		v2.x[i] = j
-		r += v2.x[j]
-	}
-
-	{
-		var v3 Vanilla2
-		v3.x[i] = j
-		r += v3.x[j]
-	}
-
-	var s Single
-	s.x[i] = j
-	r += s.x[j]
-
-	// Here p1 and p2 interfere, but p1 could be overlapped with xp3.
-	var p1, p2 Pointery
-	p1.x[i] = j
-	r += p1.x[j]
-	p2.x[i] = j
-	r += p2.x[j]
-	{
-		var xp3 Pointery2
-		xp3.x[i] = j
-		r += xp3.x[j]
-	}
-
-	if i == j*2 {
-		// p2 live on this path
-		p2.x[i] += j
-		r += p2.x[j]
-	} else {
-		// p2 not live on this path
-		var xp4 Pointery2
-		xp4.x[i] = j
-		r += xp4.x[j]
-	}
-
-	return r
-}
diff --git a/src/cmd/compile/internal/walk/temp.go b/src/cmd/compile/internal/walk/temp.go
index 604ac17..886b5be 100644
--- a/src/cmd/compile/internal/walk/temp.go
+++ b/src/cmd/compile/internal/walk/temp.go
@@ -25,9 +25,7 @@
 // allocated temporary variable of the given type. Statements to
 // zero-initialize tmp are appended to init.
 func stackTempAddr(init *ir.Nodes, typ *types.Type) *ir.AddrExpr {
-	n := typecheck.TempAt(base.Pos, ir.CurFunc, typ)
-	n.SetNonMergeable(true)
-	return initStackTemp(init, n, nil)
+	return initStackTemp(init, typecheck.TempAt(base.Pos, ir.CurFunc, typ), nil)
 }
 
 // stackBufAddr returns the expression &tmp, where tmp is a newly
diff --git a/test/fixedbugs/bug385_64.go b/test/fixedbugs/bug385_64.go
index deba9c9..3240960 100644
--- a/test/fixedbugs/bug385_64.go
+++ b/test/fixedbugs/bug385_64.go
@@ -11,423 +11,214 @@
 
 package main
 
-var z [10 << 20]byte
+var z [10<<20]byte
 
 func main() { // GC_ERROR "stack frame too large"
-	// seq 1 206 | sed 's/.*/	var x& [10<<20]byte/'
-	// seq 1 206 | sed 's/.*/	z = x&/'
-	var x1 [10<<20]byte
-	var x2 [10<<20]byte
-	var x3 [10<<20]byte
-	var x4 [10<<20]byte
-	var x5 [10<<20]byte
-	var x6 [10<<20]byte
-	var x7 [10<<20]byte
-	var x8 [10<<20]byte
-	var x9 [10<<20]byte
-	var x10 [10<<20]byte
-	var x11 [10<<20]byte
-	var x12 [10<<20]byte
-	var x13 [10<<20]byte
-	var x14 [10<<20]byte
-	var x15 [10<<20]byte
-	var x16 [10<<20]byte
-	var x17 [10<<20]byte
-	var x18 [10<<20]byte
-	var x19 [10<<20]byte
-	var x20 [10<<20]byte
-	var x21 [10<<20]byte
-	var x22 [10<<20]byte
-	var x23 [10<<20]byte
-	var x24 [10<<20]byte
-	var x25 [10<<20]byte
-	var x26 [10<<20]byte
-	var x27 [10<<20]byte
-	var x28 [10<<20]byte
-	var x29 [10<<20]byte
-	var x30 [10<<20]byte
-	var x31 [10<<20]byte
-	var x32 [10<<20]byte
-	var x33 [10<<20]byte
-	var x34 [10<<20]byte
-	var x35 [10<<20]byte
-	var x36 [10<<20]byte
-	var x37 [10<<20]byte
-	var x38 [10<<20]byte
-	var x39 [10<<20]byte
-	var x40 [10<<20]byte
-	var x41 [10<<20]byte
-	var x42 [10<<20]byte
-	var x43 [10<<20]byte
-	var x44 [10<<20]byte
-	var x45 [10<<20]byte
-	var x46 [10<<20]byte
-	var x47 [10<<20]byte
-	var x48 [10<<20]byte
-	var x49 [10<<20]byte
-	var x50 [10<<20]byte
-	var x51 [10<<20]byte
-	var x52 [10<<20]byte
-	var x53 [10<<20]byte
-	var x54 [10<<20]byte
-	var x55 [10<<20]byte
-	var x56 [10<<20]byte
-	var x57 [10<<20]byte
-	var x58 [10<<20]byte
-	var x59 [10<<20]byte
-	var x60 [10<<20]byte
-	var x61 [10<<20]byte
-	var x62 [10<<20]byte
-	var x63 [10<<20]byte
-	var x64 [10<<20]byte
-	var x65 [10<<20]byte
-	var x66 [10<<20]byte
-	var x67 [10<<20]byte
-	var x68 [10<<20]byte
-	var x69 [10<<20]byte
-	var x70 [10<<20]byte
-	var x71 [10<<20]byte
-	var x72 [10<<20]byte
-	var x73 [10<<20]byte
-	var x74 [10<<20]byte
-	var x75 [10<<20]byte
-	var x76 [10<<20]byte
-	var x77 [10<<20]byte
-	var x78 [10<<20]byte
-	var x79 [10<<20]byte
-	var x80 [10<<20]byte
-	var x81 [10<<20]byte
-	var x82 [10<<20]byte
-	var x83 [10<<20]byte
-	var x84 [10<<20]byte
-	var x85 [10<<20]byte
-	var x86 [10<<20]byte
-	var x87 [10<<20]byte
-	var x88 [10<<20]byte
-	var x89 [10<<20]byte
-	var x90 [10<<20]byte
-	var x91 [10<<20]byte
-	var x92 [10<<20]byte
-	var x93 [10<<20]byte
-	var x94 [10<<20]byte
-	var x95 [10<<20]byte
-	var x96 [10<<20]byte
-	var x97 [10<<20]byte
-	var x98 [10<<20]byte
-	var x99 [10<<20]byte
-	var x100 [10<<20]byte
-	var x101 [10<<20]byte
-	var x102 [10<<20]byte
-	var x103 [10<<20]byte
-	var x104 [10<<20]byte
-	var x105 [10<<20]byte
-	var x106 [10<<20]byte
-	var x107 [10<<20]byte
-	var x108 [10<<20]byte
-	var x109 [10<<20]byte
-	var x110 [10<<20]byte
-	var x111 [10<<20]byte
-	var x112 [10<<20]byte
-	var x113 [10<<20]byte
-	var x114 [10<<20]byte
-	var x115 [10<<20]byte
-	var x116 [10<<20]byte
-	var x117 [10<<20]byte
-	var x118 [10<<20]byte
-	var x119 [10<<20]byte
-	var x120 [10<<20]byte
-	var x121 [10<<20]byte
-	var x122 [10<<20]byte
-	var x123 [10<<20]byte
-	var x124 [10<<20]byte
-	var x125 [10<<20]byte
-	var x126 [10<<20]byte
-	var x127 [10<<20]byte
-	var x128 [10<<20]byte
-	var x129 [10<<20]byte
-	var x130 [10<<20]byte
-	var x131 [10<<20]byte
-	var x132 [10<<20]byte
-	var x133 [10<<20]byte
-	var x134 [10<<20]byte
-	var x135 [10<<20]byte
-	var x136 [10<<20]byte
-	var x137 [10<<20]byte
-	var x138 [10<<20]byte
-	var x139 [10<<20]byte
-	var x140 [10<<20]byte
-	var x141 [10<<20]byte
-	var x142 [10<<20]byte
-	var x143 [10<<20]byte
-	var x144 [10<<20]byte
-	var x145 [10<<20]byte
-	var x146 [10<<20]byte
-	var x147 [10<<20]byte
-	var x148 [10<<20]byte
-	var x149 [10<<20]byte
-	var x150 [10<<20]byte
-	var x151 [10<<20]byte
-	var x152 [10<<20]byte
-	var x153 [10<<20]byte
-	var x154 [10<<20]byte
-	var x155 [10<<20]byte
-	var x156 [10<<20]byte
-	var x157 [10<<20]byte
-	var x158 [10<<20]byte
-	var x159 [10<<20]byte
-	var x160 [10<<20]byte
-	var x161 [10<<20]byte
-	var x162 [10<<20]byte
-	var x163 [10<<20]byte
-	var x164 [10<<20]byte
-	var x165 [10<<20]byte
-	var x166 [10<<20]byte
-	var x167 [10<<20]byte
-	var x168 [10<<20]byte
-	var x169 [10<<20]byte
-	var x170 [10<<20]byte
-	var x171 [10<<20]byte
-	var x172 [10<<20]byte
-	var x173 [10<<20]byte
-	var x174 [10<<20]byte
-	var x175 [10<<20]byte
-	var x176 [10<<20]byte
-	var x177 [10<<20]byte
-	var x178 [10<<20]byte
-	var x179 [10<<20]byte
-	var x180 [10<<20]byte
-	var x181 [10<<20]byte
-	var x182 [10<<20]byte
-	var x183 [10<<20]byte
-	var x184 [10<<20]byte
-	var x185 [10<<20]byte
-	var x186 [10<<20]byte
-	var x187 [10<<20]byte
-	var x188 [10<<20]byte
-	var x189 [10<<20]byte
-	var x190 [10<<20]byte
-	var x191 [10<<20]byte
-	var x192 [10<<20]byte
-	var x193 [10<<20]byte
-	var x194 [10<<20]byte
-	var x195 [10<<20]byte
-	var x196 [10<<20]byte
-	var x197 [10<<20]byte
-	var x198 [10<<20]byte
-	var x199 [10<<20]byte
-	var x200 [10<<20]byte
-	var x201 [10<<20]byte
-	var x202 [10<<20]byte
-	var x203 [10<<20]byte
-	var x204 [10<<20]byte
-	var x205 [10<<20]byte
-	var x206 [10<<20]byte
-	var x207 [10<<20]byte
-	z = x1
-	z = x2
-	z = x3
-	z = x4
-	z = x5
-	z = x6
-	z = x7
-	z = x8
-	z = x9
-	z = x10
-	z = x11
-	z = x12
-	z = x13
-	z = x14
-	z = x15
-	z = x16
-	z = x17
-	z = x18
-	z = x19
-	z = x20
-	z = x21
-	z = x22
-	z = x23
-	z = x24
-	z = x25
-	z = x26
-	z = x27
-	z = x28
-	z = x29
-	z = x30
-	z = x31
-	z = x32
-	z = x33
-	z = x34
-	z = x35
-	z = x36
-	z = x37
-	z = x38
-	z = x39
-	z = x40
-	z = x41
-	z = x42
-	z = x43
-	z = x44
-	z = x45
-	z = x46
-	z = x47
-	z = x48
-	z = x49
-	z = x50
-	z = x51
-	z = x52
-	z = x53
-	z = x54
-	z = x55
-	z = x56
-	z = x57
-	z = x58
-	z = x59
-	z = x60
-	z = x61
-	z = x62
-	z = x63
-	z = x64
-	z = x65
-	z = x66
-	z = x67
-	z = x68
-	z = x69
-	z = x70
-	z = x71
-	z = x72
-	z = x73
-	z = x74
-	z = x75
-	z = x76
-	z = x77
-	z = x78
-	z = x79
-	z = x80
-	z = x81
-	z = x82
-	z = x83
-	z = x84
-	z = x85
-	z = x86
-	z = x87
-	z = x88
-	z = x89
-	z = x90
-	z = x91
-	z = x92
-	z = x93
-	z = x94
-	z = x95
-	z = x96
-	z = x97
-	z = x98
-	z = x99
-	z = x100
-	z = x101
-	z = x102
-	z = x103
-	z = x104
-	z = x105
-	z = x106
-	z = x107
-	z = x108
-	z = x109
-	z = x110
-	z = x111
-	z = x112
-	z = x113
-	z = x114
-	z = x115
-	z = x116
-	z = x117
-	z = x118
-	z = x119
-	z = x120
-	z = x121
-	z = x122
-	z = x123
-	z = x124
-	z = x125
-	z = x126
-	z = x127
-	z = x128
-	z = x129
-	z = x130
-	z = x131
-	z = x132
-	z = x133
-	z = x134
-	z = x135
-	z = x136
-	z = x137
-	z = x138
-	z = x139
-	z = x140
-	z = x141
-	z = x142
-	z = x143
-	z = x144
-	z = x145
-	z = x146
-	z = x147
-	z = x148
-	z = x149
-	z = x150
-	z = x151
-	z = x152
-	z = x153
-	z = x154
-	z = x155
-	z = x156
-	z = x157
-	z = x158
-	z = x159
-	z = x160
-	z = x161
-	z = x162
-	z = x163
-	z = x164
-	z = x165
-	z = x166
-	z = x167
-	z = x168
-	z = x169
-	z = x170
-	z = x171
-	z = x172
-	z = x173
-	z = x174
-	z = x175
-	z = x176
-	z = x177
-	z = x178
-	z = x179
-	z = x180
-	z = x181
-	z = x182
-	z = x183
-	z = x184
-	z = x185
-	z = x186
-	z = x187
-	z = x188
-	z = x189
-	z = x190
-	z = x191
-	z = x192
-	z = x193
-	z = x194
-	z = x195
-	z = x196
-	z = x197
-	z = x198
-	z = x199
-	z = x200
-	z = x201
-	z = x202
-	z = x203
-	z = x204
-	z = x205
-	z = x206
-	z = x207
+	// seq 1 206 | sed 's/.*/	var x& [10<<20]byte; z = x&/'
+	var x1 [10<<20]byte; z = x1
+	var x2 [10<<20]byte; z = x2
+	var x3 [10<<20]byte; z = x3
+	var x4 [10<<20]byte; z = x4
+	var x5 [10<<20]byte; z = x5
+	var x6 [10<<20]byte; z = x6
+	var x7 [10<<20]byte; z = x7
+	var x8 [10<<20]byte; z = x8
+	var x9 [10<<20]byte; z = x9
+	var x10 [10<<20]byte; z = x10
+	var x11 [10<<20]byte; z = x11
+	var x12 [10<<20]byte; z = x12
+	var x13 [10<<20]byte; z = x13
+	var x14 [10<<20]byte; z = x14
+	var x15 [10<<20]byte; z = x15
+	var x16 [10<<20]byte; z = x16
+	var x17 [10<<20]byte; z = x17
+	var x18 [10<<20]byte; z = x18
+	var x19 [10<<20]byte; z = x19
+	var x20 [10<<20]byte; z = x20
+	var x21 [10<<20]byte; z = x21
+	var x22 [10<<20]byte; z = x22
+	var x23 [10<<20]byte; z = x23
+	var x24 [10<<20]byte; z = x24
+	var x25 [10<<20]byte; z = x25
+	var x26 [10<<20]byte; z = x26
+	var x27 [10<<20]byte; z = x27
+	var x28 [10<<20]byte; z = x28
+	var x29 [10<<20]byte; z = x29
+	var x30 [10<<20]byte; z = x30
+	var x31 [10<<20]byte; z = x31
+	var x32 [10<<20]byte; z = x32
+	var x33 [10<<20]byte; z = x33
+	var x34 [10<<20]byte; z = x34
+	var x35 [10<<20]byte; z = x35
+	var x36 [10<<20]byte; z = x36
+	var x37 [10<<20]byte; z = x37
+	var x38 [10<<20]byte; z = x38
+	var x39 [10<<20]byte; z = x39
+	var x40 [10<<20]byte; z = x40
+	var x41 [10<<20]byte; z = x41
+	var x42 [10<<20]byte; z = x42
+	var x43 [10<<20]byte; z = x43
+	var x44 [10<<20]byte; z = x44
+	var x45 [10<<20]byte; z = x45
+	var x46 [10<<20]byte; z = x46
+	var x47 [10<<20]byte; z = x47
+	var x48 [10<<20]byte; z = x48
+	var x49 [10<<20]byte; z = x49
+	var x50 [10<<20]byte; z = x50
+	var x51 [10<<20]byte; z = x51
+	var x52 [10<<20]byte; z = x52
+	var x53 [10<<20]byte; z = x53
+	var x54 [10<<20]byte; z = x54
+	var x55 [10<<20]byte; z = x55
+	var x56 [10<<20]byte; z = x56
+	var x57 [10<<20]byte; z = x57
+	var x58 [10<<20]byte; z = x58
+	var x59 [10<<20]byte; z = x59
+	var x60 [10<<20]byte; z = x60
+	var x61 [10<<20]byte; z = x61
+	var x62 [10<<20]byte; z = x62
+	var x63 [10<<20]byte; z = x63
+	var x64 [10<<20]byte; z = x64
+	var x65 [10<<20]byte; z = x65
+	var x66 [10<<20]byte; z = x66
+	var x67 [10<<20]byte; z = x67
+	var x68 [10<<20]byte; z = x68
+	var x69 [10<<20]byte; z = x69
+	var x70 [10<<20]byte; z = x70
+	var x71 [10<<20]byte; z = x71
+	var x72 [10<<20]byte; z = x72
+	var x73 [10<<20]byte; z = x73
+	var x74 [10<<20]byte; z = x74
+	var x75 [10<<20]byte; z = x75
+	var x76 [10<<20]byte; z = x76
+	var x77 [10<<20]byte; z = x77
+	var x78 [10<<20]byte; z = x78
+	var x79 [10<<20]byte; z = x79
+	var x80 [10<<20]byte; z = x80
+	var x81 [10<<20]byte; z = x81
+	var x82 [10<<20]byte; z = x82
+	var x83 [10<<20]byte; z = x83
+	var x84 [10<<20]byte; z = x84
+	var x85 [10<<20]byte; z = x85
+	var x86 [10<<20]byte; z = x86
+	var x87 [10<<20]byte; z = x87
+	var x88 [10<<20]byte; z = x88
+	var x89 [10<<20]byte; z = x89
+	var x90 [10<<20]byte; z = x90
+	var x91 [10<<20]byte; z = x91
+	var x92 [10<<20]byte; z = x92
+	var x93 [10<<20]byte; z = x93
+	var x94 [10<<20]byte; z = x94
+	var x95 [10<<20]byte; z = x95
+	var x96 [10<<20]byte; z = x96
+	var x97 [10<<20]byte; z = x97
+	var x98 [10<<20]byte; z = x98
+	var x99 [10<<20]byte; z = x99
+	var x100 [10<<20]byte; z = x100
+	var x101 [10<<20]byte; z = x101
+	var x102 [10<<20]byte; z = x102
+	var x103 [10<<20]byte; z = x103
+	var x104 [10<<20]byte; z = x104
+	var x105 [10<<20]byte; z = x105
+	var x106 [10<<20]byte; z = x106
+	var x107 [10<<20]byte; z = x107
+	var x108 [10<<20]byte; z = x108
+	var x109 [10<<20]byte; z = x109
+	var x110 [10<<20]byte; z = x110
+	var x111 [10<<20]byte; z = x111
+	var x112 [10<<20]byte; z = x112
+	var x113 [10<<20]byte; z = x113
+	var x114 [10<<20]byte; z = x114
+	var x115 [10<<20]byte; z = x115
+	var x116 [10<<20]byte; z = x116
+	var x117 [10<<20]byte; z = x117
+	var x118 [10<<20]byte; z = x118
+	var x119 [10<<20]byte; z = x119
+	var x120 [10<<20]byte; z = x120
+	var x121 [10<<20]byte; z = x121
+	var x122 [10<<20]byte; z = x122
+	var x123 [10<<20]byte; z = x123
+	var x124 [10<<20]byte; z = x124
+	var x125 [10<<20]byte; z = x125
+	var x126 [10<<20]byte; z = x126
+	var x127 [10<<20]byte; z = x127
+	var x128 [10<<20]byte; z = x128
+	var x129 [10<<20]byte; z = x129
+	var x130 [10<<20]byte; z = x130
+	var x131 [10<<20]byte; z = x131
+	var x132 [10<<20]byte; z = x132
+	var x133 [10<<20]byte; z = x133
+	var x134 [10<<20]byte; z = x134
+	var x135 [10<<20]byte; z = x135
+	var x136 [10<<20]byte; z = x136
+	var x137 [10<<20]byte; z = x137
+	var x138 [10<<20]byte; z = x138
+	var x139 [10<<20]byte; z = x139
+	var x140 [10<<20]byte; z = x140
+	var x141 [10<<20]byte; z = x141
+	var x142 [10<<20]byte; z = x142
+	var x143 [10<<20]byte; z = x143
+	var x144 [10<<20]byte; z = x144
+	var x145 [10<<20]byte; z = x145
+	var x146 [10<<20]byte; z = x146
+	var x147 [10<<20]byte; z = x147
+	var x148 [10<<20]byte; z = x148
+	var x149 [10<<20]byte; z = x149
+	var x150 [10<<20]byte; z = x150
+	var x151 [10<<20]byte; z = x151
+	var x152 [10<<20]byte; z = x152
+	var x153 [10<<20]byte; z = x153
+	var x154 [10<<20]byte; z = x154
+	var x155 [10<<20]byte; z = x155
+	var x156 [10<<20]byte; z = x156
+	var x157 [10<<20]byte; z = x157
+	var x158 [10<<20]byte; z = x158
+	var x159 [10<<20]byte; z = x159
+	var x160 [10<<20]byte; z = x160
+	var x161 [10<<20]byte; z = x161
+	var x162 [10<<20]byte; z = x162
+	var x163 [10<<20]byte; z = x163
+	var x164 [10<<20]byte; z = x164
+	var x165 [10<<20]byte; z = x165
+	var x166 [10<<20]byte; z = x166
+	var x167 [10<<20]byte; z = x167
+	var x168 [10<<20]byte; z = x168
+	var x169 [10<<20]byte; z = x169
+	var x170 [10<<20]byte; z = x170
+	var x171 [10<<20]byte; z = x171
+	var x172 [10<<20]byte; z = x172
+	var x173 [10<<20]byte; z = x173
+	var x174 [10<<20]byte; z = x174
+	var x175 [10<<20]byte; z = x175
+	var x176 [10<<20]byte; z = x176
+	var x177 [10<<20]byte; z = x177
+	var x178 [10<<20]byte; z = x178
+	var x179 [10<<20]byte; z = x179
+	var x180 [10<<20]byte; z = x180
+	var x181 [10<<20]byte; z = x181
+	var x182 [10<<20]byte; z = x182
+	var x183 [10<<20]byte; z = x183
+	var x184 [10<<20]byte; z = x184
+	var x185 [10<<20]byte; z = x185
+	var x186 [10<<20]byte; z = x186
+	var x187 [10<<20]byte; z = x187
+	var x188 [10<<20]byte; z = x188
+	var x189 [10<<20]byte; z = x189
+	var x190 [10<<20]byte; z = x190
+	var x191 [10<<20]byte; z = x191
+	var x192 [10<<20]byte; z = x192
+	var x193 [10<<20]byte; z = x193
+	var x194 [10<<20]byte; z = x194
+	var x195 [10<<20]byte; z = x195
+	var x196 [10<<20]byte; z = x196
+	var x197 [10<<20]byte; z = x197
+	var x198 [10<<20]byte; z = x198
+	var x199 [10<<20]byte; z = x199
+	var x200 [10<<20]byte; z = x200
+	var x201 [10<<20]byte; z = x201
+	var x202 [10<<20]byte; z = x202
+	var x203 [10<<20]byte; z = x203
+	var x204 [10<<20]byte; z = x204
+	var x205 [10<<20]byte; z = x205
+	var x206 [10<<20]byte; z = x206
 }