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| author | Joel Sing <joel@sing.id.au> | 2022-09-09 23:15:46 +1000 |
|---|---|---|
| committer | Joel Sing <joel@sing.id.au> | 2022-10-11 04:04:13 +0000 |
| commit | 4274ffd4b8bcef4e07cfdef9405a2e33f935d079 (patch) | |
| tree | 02e5f5e761059f3db2896e12040ec3764dd7c9f0 | |
| parent | ba8c94b5f255bf84d05cf90d3d66621ffd2e0fab (diff) | |
| download | go-4274ffd4b8bcef4e07cfdef9405a2e33f935d079.tar.xz | |
cmd/compile: fold negation into subtraction on riscv64
Fold negation into subtraction and avoid double negation.
This removes around 500 instructions from the Go binary on riscv64.
Change-Id: I4aac6c87baa2a0759b180ba87876d488a23df6d7
Reviewed-on: https://go-review.googlesource.com/c/go/+/431105
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joedian Reid <joedian@golang.org>
Reviewed-by: Wayne Zuo <wdvxdr@golangcn.org>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
| -rw-r--r-- | src/cmd/compile/internal/ssa/_gen/RISCV64.rules | 7 | ||||
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewriteRISCV64.go | 49 |
2 files changed, 56 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/_gen/RISCV64.rules b/src/cmd/compile/internal/ssa/_gen/RISCV64.rules index 6119f3482b..78c3375e2d 100644 --- a/src/cmd/compile/internal/ssa/_gen/RISCV64.rules +++ b/src/cmd/compile/internal/ssa/_gen/RISCV64.rules @@ -778,6 +778,13 @@ (SUB (MOVDconst [0]) x) => (NEG x) (SUBW (MOVDconst [0]) x) => (NEGW x) +// Fold negation into subtraction. +(NEG (SUB x y)) => (SUB y x) +(NEG <t> s:(ADDI [val] (SUB x y))) && s.Uses == 1 && is32Bit(-val) => (ADDI [-val] (SUB <t> y x)) + +// Double negation. +(NEG (NEG x)) => x + // Addition of zero or two constants. (ADDI [0] x) => x (ADDI [x] (MOVDconst [y])) && is32Bit(x + y) => (MOVDconst [x + y]) diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go index 31ec233e61..d362b668c8 100644 --- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go +++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go @@ -5437,6 +5437,55 @@ func rewriteValueRISCV64_OpRISCV64MOVWstorezero(v *Value) bool { } func rewriteValueRISCV64_OpRISCV64NEG(v *Value) bool { v_0 := v.Args[0] + b := v.Block + // match: (NEG (SUB x y)) + // result: (SUB y x) + for { + if v_0.Op != OpRISCV64SUB { + break + } + y := v_0.Args[1] + x := v_0.Args[0] + v.reset(OpRISCV64SUB) + v.AddArg2(y, x) + return true + } + // match: (NEG <t> s:(ADDI [val] (SUB x y))) + // cond: s.Uses == 1 && is32Bit(-val) + // result: (ADDI [-val] (SUB <t> y x)) + for { + t := v.Type + s := v_0 + if s.Op != OpRISCV64ADDI { + break + } + val := auxIntToInt64(s.AuxInt) + s_0 := s.Args[0] + if s_0.Op != OpRISCV64SUB { + break + } + y := s_0.Args[1] + x := s_0.Args[0] + if !(s.Uses == 1 && is32Bit(-val)) { + break + } + v.reset(OpRISCV64ADDI) + v.AuxInt = int64ToAuxInt(-val) + v0 := b.NewValue0(v.Pos, OpRISCV64SUB, t) + v0.AddArg2(y, x) + v.AddArg(v0) + return true + } + // match: (NEG (NEG x)) + // result: x + for { + if v_0.Op != OpRISCV64NEG { + break + } + x := v_0.Args[0] + v.copyOf(x) + return true + } // match: (NEG (MOVDconst [x])) // result: (MOVDconst [-x]) for { |