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cmd/compile: prefer rematerializeable arg0 for HMUL

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This prevents accidental regalloc regressions
that otherwise can occur from unrelated changes.

Change-Id: Iea356fb1a24766361fce13748dc1b46e57b21cea
Reviewed-on: https://go-review.googlesource.com/129375
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Josh Bleecher Snyder 2018-06-16 06:54:23 -07:00
parent 2179e495ce
commit 24e51bbe64
2 changed files with 87 additions and 0 deletions
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7
src/cmd/compile/internal/ssa/gen/AMD64.rules
View File

@ -2430,6 +2430,13 @@
// See issue 22947 for details
(ADD(Q|L)const [off] x:(SP)) -> (LEA(Q|L) [off] x)
// HMULx is commutative, but its first argument must go in AX.
// If possible, put a rematerializeable value in the first argument slot,
// to reduce the odds that another value will be have to spilled
// specifically to free up AX.
(HMUL(Q|L) x y) && !x.rematerializeable() && y.rematerializeable() -> (HMUL(Q|L) y x)
(HMUL(Q|L)U x y) && !x.rematerializeable() && y.rematerializeable() -> (HMUL(Q|L)U y x)
// Fold loads into compares
// Note: these may be undone by the flagalloc pass.
(CMP(Q|L|W|B) l:(MOV(Q|L|W|B)load {sym} [off] ptr mem) x) && canMergeLoad(v, l, x) && clobber(l) -> (CMP(Q|L|W|B)load {sym} [off] ptr x mem)

80
src/cmd/compile/internal/ssa/rewriteAMD64.go
View File

@ -173,6 +173,14 @@ func rewriteValueAMD64(v *Value) bool {
return rewriteValueAMD64_OpAMD64DIVSS_0(v)
case OpAMD64DIVSSload:
return rewriteValueAMD64_OpAMD64DIVSSload_0(v)
case OpAMD64HMULL:
return rewriteValueAMD64_OpAMD64HMULL_0(v)
case OpAMD64HMULLU:
return rewriteValueAMD64_OpAMD64HMULLU_0(v)
case OpAMD64HMULQ:
return rewriteValueAMD64_OpAMD64HMULQ_0(v)
case OpAMD64HMULQU:
return rewriteValueAMD64_OpAMD64HMULQU_0(v)
case OpAMD64LEAL:
return rewriteValueAMD64_OpAMD64LEAL_0(v)
case OpAMD64LEAL1:
@ -9238,6 +9246,78 @@ func rewriteValueAMD64_OpAMD64DIVSSload_0(v *Value) bool {
}
return false
}
func rewriteValueAMD64_OpAMD64HMULL_0(v *Value) bool {
// match: (HMULL x y)
// cond: !x.rematerializeable() && y.rematerializeable()
// result: (HMULL y x)
for {
_ = v.Args[1]
x := v.Args[0]
y := v.Args[1]
if !(!x.rematerializeable() && y.rematerializeable()) {
break
}
v.reset(OpAMD64HMULL)
v.AddArg(y)
v.AddArg(x)
return true
}
return false
}
func rewriteValueAMD64_OpAMD64HMULLU_0(v *Value) bool {
// match: (HMULLU x y)
// cond: !x.rematerializeable() && y.rematerializeable()
// result: (HMULLU y x)
for {
_ = v.Args[1]
x := v.Args[0]
y := v.Args[1]
if !(!x.rematerializeable() && y.rematerializeable()) {
break
}
v.reset(OpAMD64HMULLU)
v.AddArg(y)
v.AddArg(x)
return true
}
return false
}
func rewriteValueAMD64_OpAMD64HMULQ_0(v *Value) bool {
// match: (HMULQ x y)
// cond: !x.rematerializeable() && y.rematerializeable()
// result: (HMULQ y x)
for {
_ = v.Args[1]
x := v.Args[0]
y := v.Args[1]
if !(!x.rematerializeable() && y.rematerializeable()) {
break
}
v.reset(OpAMD64HMULQ)
v.AddArg(y)
v.AddArg(x)
return true
}
return false
}
func rewriteValueAMD64_OpAMD64HMULQU_0(v *Value) bool {
// match: (HMULQU x y)
// cond: !x.rematerializeable() && y.rematerializeable()
// result: (HMULQU y x)
for {
_ = v.Args[1]
x := v.Args[0]
y := v.Args[1]
if !(!x.rematerializeable() && y.rematerializeable()) {
break
}
v.reset(OpAMD64HMULQU)
v.AddArg(y)
v.AddArg(x)
return true
}
return false
}
func rewriteValueAMD64_OpAMD64LEAL_0(v *Value) bool {
// match: (LEAL [c] {s} (ADDLconst [d] x))
// cond: is32Bit(c+d)