[dev.ssa] cmd/compile: fix failed lowerings
One was OAPPEND of large types. We need to mem-mem copy them
instead of storing them.
Another was pointer-like struct and array types being put in the
data field of an eface. We need to use the underlying pointer
type for the load that fills in the eface.data field.
Change-Id: Id8278c0381904e52d59011a66ce46386b41b5521
Reviewed-on: https://go-review.googlesource.com/15552
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 7e00fc9..69a9b86 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -1801,6 +1801,31 @@
case OEFACE:
tab := s.expr(n.Left)
data := s.expr(n.Right)
+ // The frontend allows putting things like struct{*byte} in
+ // the data portion of an eface. But we don't want struct{*byte}
+ // as a register type because (among other reasons) the liveness
+ // analysis is confused by the "fat" variables that result from
+ // such types being spilled.
+ // So here we ensure that we are selecting the underlying pointer
+ // when we build an eface.
+ for !data.Type.IsPtr() {
+ switch {
+ case data.Type.IsArray():
+ data = s.newValue2(ssa.OpArrayIndex, data.Type.Elem(), data, s.constInt(Types[TINT], 0))
+ case data.Type.IsStruct():
+ for i := data.Type.NumFields() - 1; i >= 0; i-- {
+ f := data.Type.FieldType(i)
+ if f.Size() == 0 {
+ // eface type could also be struct{p *byte; q [0]int}
+ continue
+ }
+ data = s.newValue1I(ssa.OpStructSelect, f, data.Type.FieldOff(i), data)
+ break
+ }
+ default:
+ s.Fatalf("type being put into an eface isn't a pointer")
+ }
+ }
return s.newValue2(ssa.OpIMake, n.Type, tab, data)
case OSLICE, OSLICEARR:
@@ -1898,8 +1923,15 @@
// Evaluate args
args := make([]*ssa.Value, 0, nargs)
+ store := make([]bool, 0, nargs)
for l := n.List.Next; l != nil; l = l.Next {
- args = append(args, s.expr(l.N))
+ if canSSAType(l.N.Type) {
+ args = append(args, s.expr(l.N))
+ store = append(store, true)
+ } else {
+ args = append(args, s.addr(l.N))
+ store = append(store, false)
+ }
}
p = s.variable(&ptrVar, pt) // generates phi for ptr
@@ -1907,7 +1939,11 @@
p2 := s.newValue2(ssa.OpPtrIndex, pt, p, l)
for i, arg := range args {
addr := s.newValue2(ssa.OpPtrIndex, pt, p2, s.constInt(Types[TUINTPTR], int64(i)))
- s.vars[&memVar] = s.newValue3I(ssa.OpStore, ssa.TypeMem, et.Size(), addr, arg, s.mem())
+ if store[i] {
+ s.vars[&memVar] = s.newValue3I(ssa.OpStore, ssa.TypeMem, et.Size(), addr, arg, s.mem())
+ } else {
+ s.vars[&memVar] = s.newValue3I(ssa.OpMove, ssa.TypeMem, et.Size(), addr, arg, s.mem())
+ }
if haspointers(et) {
// TODO: just one write barrier call for all of these writes?
// TODO: maybe just one writeBarrierEnabled check?
