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cmd/compile: remove BTQconst rule

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This rule is meant for code optimization, but it makes other rules
potentially more complex, as they need to cope with the fact that
a 32-bit op (BTLconst) can appear everywhere a 64-bit rule maches.

Move the optimization to opcode expansion instead. Tests will be
added in following CL.

Change-Id: Ica5ef291e7963c4af17c124d4a2869e6c8f7b0c7
Reviewed-on: https://go-review.googlesource.com/99995
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Giovanni Bajo 2018-03-10 11:17:05 +01:00
parent e601c07908
commit eb44b8635c
3 changed files with 12 additions and 24 deletions
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14
src/cmd/compile/internal/amd64/ssa.go
View File

@ -562,8 +562,18 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p.From.Reg = v.Args[0].Reg()
p.To.Type = obj.TYPE_CONST
p.To.Offset = v.AuxInt
case ssa.OpAMD64TESTQconst, ssa.OpAMD64TESTLconst, ssa.OpAMD64TESTWconst, ssa.OpAMD64TESTBconst,
ssa.OpAMD64BTLconst, ssa.OpAMD64BTQconst:
case ssa.OpAMD64BTLconst, ssa.OpAMD64BTQconst:
op := v.Op
if op == ssa.OpAMD64BTQconst && v.AuxInt < 32 {
// Emit 32-bit version because it's shorter
op = ssa.OpAMD64BTLconst
}
p := s.Prog(op.Asm())
p.From.Type = obj.TYPE_CONST
p.From.Offset = v.AuxInt
p.To.Type = obj.TYPE_REG
p.To.Reg = v.Args[0].Reg()
case ssa.OpAMD64TESTQconst, ssa.OpAMD64TESTLconst, ssa.OpAMD64TESTWconst, ssa.OpAMD64TESTBconst:
p := s.Prog(v.Op.Asm())
p.From.Type = obj.TYPE_CONST
p.From.Offset = v.AuxInt

3
src/cmd/compile/internal/ssa/gen/AMD64.rules
View File

@ -666,9 +666,6 @@
(XORLconst [1] (SETBE x)) -> (SETA x)
(XORLconst [1] (SETA x)) -> (SETBE x)
// Convert BTQconst to BTLconst if possible. It has a shorter encoding.
(BTQconst [c] x) && c < 32 -> (BTLconst [c] x)
// Special case for floating point - LF/LEF not generated
(NE (TESTB (SETGF cmp) (SETGF cmp)) yes no) -> (UGT cmp yes no)
(NE (TESTB (SETGEF cmp) (SETGEF cmp)) yes no) -> (UGE cmp yes no)

19
src/cmd/compile/internal/ssa/rewriteAMD64.go
View File

@ -53,8 +53,6 @@ func rewriteValueAMD64(v *Value) bool {
return rewriteValueAMD64_OpAMD64ANDQmem_0(v)
case OpAMD64BSFQ:
return rewriteValueAMD64_OpAMD64BSFQ_0(v)
case OpAMD64BTQconst:
return rewriteValueAMD64_OpAMD64BTQconst_0(v)
case OpAMD64CMOVLCC:
return rewriteValueAMD64_OpAMD64CMOVLCC_0(v)
case OpAMD64CMOVLCS:
@ -3336,23 +3334,6 @@ func rewriteValueAMD64_OpAMD64BSFQ_0(v *Value) bool {
}
return false
}
func rewriteValueAMD64_OpAMD64BTQconst_0(v *Value) bool {
// match: (BTQconst [c] x)
// cond: c < 32
// result: (BTLconst [c] x)
for {
c := v.AuxInt
x := v.Args[0]
if !(c < 32) {
break
}
v.reset(OpAMD64BTLconst)
v.AuxInt = c
v.AddArg(x)
return true
}
return false
}
func rewriteValueAMD64_OpAMD64CMOVLCC_0(v *Value) bool {
// match: (CMOVLCC x y (InvertFlags cond))
// cond: