cmd/compile: eliminate successive swaps
The code generated when storing eight bytes loaded from memory in big
endian introduced two successive byte swaps that did not actually
modified the data.
The new rules match this specific pattern both for amd64 and for arm64,
eliminating the double swap.
Fixes #41684
Change-Id: Icb6dc20b68e4393cef4fe6a07b33aba0d18c3ff3
Reviewed-on: https://go-review.googlesource.com/c/go/+/320073
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Daniel Martí <mvdan@mvdan.cc>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index 1c63a3f..9c476d8 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -2217,3 +2217,5 @@
(AND(Q|L) x (NEG(Q|L) x)) && buildcfg.GOAMD64 >= 3 => (BLSI(Q|L) x)
(XOR(Q|L) x (ADD(Q|L)const [-1] x)) && buildcfg.GOAMD64 >= 3 => (BLSMSK(Q|L) x)
(AND(Q|L) x (ADD(Q|L)const [-1] x)) && buildcfg.GOAMD64 >= 3 => (BLSR(Q|L) x)
+
+(BSWAP(Q|L) (BSWAP(Q|L) p)) => p
diff --git a/src/cmd/compile/internal/ssa/gen/ARM64.rules b/src/cmd/compile/internal/ssa/gen/ARM64.rules
index 02fb4e1..d34e189 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64.rules
+++ b/src/cmd/compile/internal/ssa/gen/ARM64.rules
@@ -2931,3 +2931,5 @@
&& isInlinableMemmove(dst, src, sz, config)
&& clobber(call)
=> (Move [sz] dst src mem)
+
+((REV|REVW) ((REV|REVW) p)) => p
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index 10d3afb..88c76dd 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -70,6 +70,10 @@
return rewriteValueAMD64_OpAMD64ANDQmodify(v)
case OpAMD64BSFQ:
return rewriteValueAMD64_OpAMD64BSFQ(v)
+ case OpAMD64BSWAPL:
+ return rewriteValueAMD64_OpAMD64BSWAPL(v)
+ case OpAMD64BSWAPQ:
+ return rewriteValueAMD64_OpAMD64BSWAPQ(v)
case OpAMD64BTCLconst:
return rewriteValueAMD64_OpAMD64BTCLconst(v)
case OpAMD64BTCQconst:
@@ -3607,6 +3611,34 @@
}
return false
}
+func rewriteValueAMD64_OpAMD64BSWAPL(v *Value) bool {
+ v_0 := v.Args[0]
+ // match: (BSWAPL (BSWAPL p))
+ // result: p
+ for {
+ if v_0.Op != OpAMD64BSWAPL {
+ break
+ }
+ p := v_0.Args[0]
+ v.copyOf(p)
+ return true
+ }
+ return false
+}
+func rewriteValueAMD64_OpAMD64BSWAPQ(v *Value) bool {
+ v_0 := v.Args[0]
+ // match: (BSWAPQ (BSWAPQ p))
+ // result: p
+ for {
+ if v_0.Op != OpAMD64BSWAPQ {
+ break
+ }
+ p := v_0.Args[0]
+ v.copyOf(p)
+ return true
+ }
+ return false
+}
func rewriteValueAMD64_OpAMD64BTCLconst(v *Value) bool {
v_0 := v.Args[0]
// match: (BTCLconst [c] (XORLconst [d] x))
diff --git a/src/cmd/compile/internal/ssa/rewriteARM64.go b/src/cmd/compile/internal/ssa/rewriteARM64.go
index 8ad9e40..ad34855 100644
--- a/src/cmd/compile/internal/ssa/rewriteARM64.go
+++ b/src/cmd/compile/internal/ssa/rewriteARM64.go
@@ -335,6 +335,10 @@
return rewriteValueARM64_OpARM64ORshiftRL(v)
case OpARM64ORshiftRO:
return rewriteValueARM64_OpARM64ORshiftRO(v)
+ case OpARM64REV:
+ return rewriteValueARM64_OpARM64REV(v)
+ case OpARM64REVW:
+ return rewriteValueARM64_OpARM64REVW(v)
case OpARM64ROR:
return rewriteValueARM64_OpARM64ROR(v)
case OpARM64RORW:
@@ -20299,6 +20303,34 @@
}
return false
}
+func rewriteValueARM64_OpARM64REV(v *Value) bool {
+ v_0 := v.Args[0]
+ // match: (REV (REV p))
+ // result: p
+ for {
+ if v_0.Op != OpARM64REV {
+ break
+ }
+ p := v_0.Args[0]
+ v.copyOf(p)
+ return true
+ }
+ return false
+}
+func rewriteValueARM64_OpARM64REVW(v *Value) bool {
+ v_0 := v.Args[0]
+ // match: (REVW (REVW p))
+ // result: p
+ for {
+ if v_0.Op != OpARM64REVW {
+ break
+ }
+ p := v_0.Args[0]
+ v.copyOf(p)
+ return true
+ }
+ return false
+}
func rewriteValueARM64_OpARM64ROR(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]
diff --git a/test/codegen/memcombine.go b/test/codegen/memcombine.go
index d74dae0..2a0c534 100644
--- a/test/codegen/memcombine.go
+++ b/test/codegen/memcombine.go
@@ -432,6 +432,18 @@
binary.BigEndian.PutUint32(b, sink32)
}
+func store_be64_load(b, x *[8]byte) {
+ // arm64:-`REV`
+ // amd64:-`BSWAPQ`
+ binary.BigEndian.PutUint64(b[:], binary.BigEndian.Uint64(x[:]))
+}
+
+func store_be32_load(b, x *[8]byte) {
+ // arm64:-`REVW`
+ // amd64:-`BSWAPL`
+ binary.BigEndian.PutUint32(b[:], binary.BigEndian.Uint32(x[:]))
+}
+
func store_be32_idx(b []byte, idx int) {
// amd64:`BSWAPL`,-`SHR.`
// arm64:`REVW`,`MOVW\sR[0-9]+,\s\(R[0-9]+\)\(R[0-9]+\)`,-`MOV[BH]`,-`REV16W`
