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| author | Keith Randall <khr@golang.org> | 2021-01-07 14:57:53 -0800 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2021-01-08 05:00:06 +0000 |
| commit | 304f769ffc68e64244266b3aadbf91e6738c0064 (patch) | |
| tree | fe443868201a208fac12c485149f7922416d4c57 /src/cmd/compile/internal/ssa/rewritegeneric.go | |
| parent | ae9771713383c1ee01a544cd50cfdbc22841380a (diff) | |
| download | go-304f769ffc68e64244266b3aadbf91e6738c0064.tar.gz go-304f769ffc68e64244266b3aadbf91e6738c0064.zip | |
cmd/compile: don't short-circuit copies whose source is volatile
Current optimization: When we copy a->b and then b->c, we might as well
copy a->c instead of b->c (then b might be dead and go away).
*Except* if a is a volatile location (might be clobbered by a call).
In that case, we really do want to copy a immediately, because there
might be a call before we can do the a->c copy.
User calls can't happen in between, because the rule matches up the
memory states. But calls inserted for memory barriers, particularly
runtime.typedmemmove, can.
(I guess we could introduce a register-calling-convention version
of runtime.typedmemmove, but that seems a bigger change than this one.)
Fixes #43570
Change-Id: Ifa518bb1a6f3a8dd46c352d4fd54ea9713b3eb1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/282492
Trust: Keith Randall <khr@golang.org>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Diffstat (limited to 'src/cmd/compile/internal/ssa/rewritegeneric.go')
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewritegeneric.go | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go index 4cb9a8f328..958e24d29f 100644 --- a/src/cmd/compile/internal/ssa/rewritegeneric.go +++ b/src/cmd/compile/internal/ssa/rewritegeneric.go @@ -13637,7 +13637,7 @@ func rewriteValuegeneric_OpMove(v *Value) bool { return true } // match: (Move {t1} [s] dst tmp1 midmem:(Move {t2} [s] tmp2 src _)) - // cond: t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config)) + // cond: t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && !isVolatile(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config)) // result: (Move {t1} [s] dst src midmem) for { s := auxIntToInt64(v.AuxInt) @@ -13651,7 +13651,7 @@ func rewriteValuegeneric_OpMove(v *Value) bool { t2 := auxToType(midmem.Aux) src := midmem.Args[1] tmp2 := midmem.Args[0] - if !(t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config))) { + if !(t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && !isVolatile(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config))) { break } v.reset(OpMove) @@ -13661,7 +13661,7 @@ func rewriteValuegeneric_OpMove(v *Value) bool { return true } // match: (Move {t1} [s] dst tmp1 midmem:(VarDef (Move {t2} [s] tmp2 src _))) - // cond: t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config)) + // cond: t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && !isVolatile(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config)) // result: (Move {t1} [s] dst src midmem) for { s := auxIntToInt64(v.AuxInt) @@ -13679,7 +13679,7 @@ func rewriteValuegeneric_OpMove(v *Value) bool { t2 := auxToType(midmem_0.Aux) src := midmem_0.Args[1] tmp2 := midmem_0.Args[0] - if !(t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config))) { + if !(t1.Compare(t2) == types.CMPeq && isSamePtr(tmp1, tmp2) && isStackPtr(src) && !isVolatile(src) && disjoint(src, s, tmp2, s) && (disjoint(src, s, dst, s) || isInlinableMemmove(dst, src, s, config))) { break } v.reset(OpMove) |