diff options
| author | Josh Bleecher Snyder <josharian@gmail.com> | 2019-04-20 11:09:34 -0700 |
|---|---|---|
| committer | Josh Bleecher Snyder <josharian@gmail.com> | 2019-04-20 19:34:03 +0000 |
| commit | 68d4b1265ec7915dccfccf6c0e32f9ab2d9c3a86 (patch) | |
| tree | ec4088bbe86f6c81e917f2db3a03e4784e14dd35 /src | |
| parent | d23cba683e59f6092c1e3f676c8e83e7973f27dd (diff) | |
| download | go-68d4b1265ec7915dccfccf6c0e32f9ab2d9c3a86.tar.xz | |
cmd/compile: reduce bits.Div64(0, lo, y) to 64 bit division
With this change, these two functions generate identical code:
func f(x uint64) (uint64, uint64) {
return bits.Div64(0, x, 5)
}
func g(x uint64) (uint64, uint64) {
return x / 5, x % 5
}
Updates #31582
Change-Id: Ia96c2e67f8af5dd985823afee5f155608c04a4b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/173197
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/ssa/gen/generic.rules | 2 | ||||
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewritegeneric.go | 54 |
2 files changed, 56 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/gen/generic.rules b/src/cmd/compile/internal/ssa/gen/generic.rules index aac7438e0a..510cec0f4b 100644 --- a/src/cmd/compile/internal/ssa/gen/generic.rules +++ b/src/cmd/compile/internal/ssa/gen/generic.rules @@ -146,6 +146,8 @@ (Div64u (Const64 [c]) (Const64 [d])) && d != 0 -> (Const64 [int64(uint64(c)/uint64(d))]) (Div32F (Const32F [c]) (Const32F [d])) -> (Const32F [auxFrom32F(auxTo32F(c) / auxTo32F(d))]) (Div64F (Const64F [c]) (Const64F [d])) -> (Const64F [auxFrom64F(auxTo64F(c) / auxTo64F(d))]) +(Select0 (Div128u (Const64 [0]) lo y)) -> (Div64u lo y) +(Select1 (Div128u (Const64 [0]) lo y)) -> (Mod64u lo y) (Not (ConstBool [c])) -> (ConstBool [1-c]) diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go index 7bb446cf35..fe2fbb82c0 100644 --- a/src/cmd/compile/internal/ssa/rewritegeneric.go +++ b/src/cmd/compile/internal/ssa/rewritegeneric.go @@ -389,6 +389,10 @@ func rewriteValuegeneric(v *Value) bool { return rewriteValuegeneric_OpRsh8x64_0(v) case OpRsh8x8: return rewriteValuegeneric_OpRsh8x8_0(v) + case OpSelect0: + return rewriteValuegeneric_OpSelect0_0(v) + case OpSelect1: + return rewriteValuegeneric_OpSelect1_0(v) case OpSignExt16to32: return rewriteValuegeneric_OpSignExt16to32_0(v) case OpSignExt16to64: @@ -26587,6 +26591,56 @@ func rewriteValuegeneric_OpRsh8x8_0(v *Value) bool { } return false } +func rewriteValuegeneric_OpSelect0_0(v *Value) bool { + // match: (Select0 (Div128u (Const64 [0]) lo y)) + // cond: + // result: (Div64u lo y) + for { + v_0 := v.Args[0] + if v_0.Op != OpDiv128u { + break + } + y := v_0.Args[2] + v_0_0 := v_0.Args[0] + if v_0_0.Op != OpConst64 { + break + } + if v_0_0.AuxInt != 0 { + break + } + lo := v_0.Args[1] + v.reset(OpDiv64u) + v.AddArg(lo) + v.AddArg(y) + return true + } + return false +} +func rewriteValuegeneric_OpSelect1_0(v *Value) bool { + // match: (Select1 (Div128u (Const64 [0]) lo y)) + // cond: + // result: (Mod64u lo y) + for { + v_0 := v.Args[0] + if v_0.Op != OpDiv128u { + break + } + y := v_0.Args[2] + v_0_0 := v_0.Args[0] + if v_0_0.Op != OpConst64 { + break + } + if v_0_0.AuxInt != 0 { + break + } + lo := v_0.Args[1] + v.reset(OpMod64u) + v.AddArg(lo) + v.AddArg(y) + return true + } + return false +} func rewriteValuegeneric_OpSignExt16to32_0(v *Value) bool { // match: (SignExt16to32 (Const16 [c])) // cond: |