diff options
| author | Joel Sing <joel@sing.id.au> | 2022-08-29 20:36:51 +1000 |
|---|---|---|
| committer | Joel Sing <joel@sing.id.au> | 2022-09-07 05:37:53 +0000 |
| commit | c011270fa56303c0f16a8cfa9b37f37f470a45bb (patch) | |
| tree | 04367c3cfe971affe239c51c791023e6a926773c /src | |
| parent | ba1ef54c1ee0e5ed8fd572dbb4ec67548cd5a55e (diff) | |
| download | go-c011270fa56303c0f16a8cfa9b37f37f470a45bb.tar.xz | |
cmd/compile: improve Slicemask on riscv64
Implement Slicemask the same way every other architecture does - negate
then arithmetic right shift. This sets or clears the sign bit, before
extending it to the entire register.
Removes around 2,500 instructions from the Go binary on linux/riscv64.
Change-Id: I4d675b826e7eb23fe2b1e6e46b95dcd49ab49733
Reviewed-on: https://go-review.googlesource.com/c/go/+/426354
Reviewed-by: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Wayne Zuo <wdvxdr@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/ssa/gen/RISCV64.rules | 9 | ||||
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewriteRISCV64.go | 13 |
2 files changed, 6 insertions, 16 deletions
diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64.rules b/src/cmd/compile/internal/ssa/gen/RISCV64.rules index 9d3cb06697..0207fb45d6 100644 --- a/src/cmd/compile/internal/ssa/gen/RISCV64.rules +++ b/src/cmd/compile/internal/ssa/gen/RISCV64.rules @@ -142,14 +142,7 @@ (Round32F ...) => (Copy ...) (Round64F ...) => (Copy ...) -// From genericOps.go: -// "0 if arg0 == 0, -1 if arg0 > 0, undef if arg0<0" -// -// Like other arches, we compute ~((x-1) >> 63), with arithmetic right shift. -// For positive x, bit 63 of x-1 is always 0, so the result is -1. -// For zero x, bit 63 of x-1 is 1, so the result is 0. -// -(Slicemask <t> x) => (NOT (SRAI <t> [63] (ADDI <t> [-1] x))) +(Slicemask <t> x) => (SRAI [63] (NEG <t> x)) // Truncations // We ignore the unused high parts of registers, so truncates are just copies. diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go index 6244488992..908456b0aa 100644 --- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go +++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go @@ -7329,17 +7329,14 @@ func rewriteValueRISCV64_OpSlicemask(v *Value) bool { v_0 := v.Args[0] b := v.Block // match: (Slicemask <t> x) - // result: (NOT (SRAI <t> [63] (ADDI <t> [-1] x))) + // result: (SRAI [63] (NEG <t> x)) for { t := v.Type x := v_0 - v.reset(OpRISCV64NOT) - v0 := b.NewValue0(v.Pos, OpRISCV64SRAI, t) - v0.AuxInt = int64ToAuxInt(63) - v1 := b.NewValue0(v.Pos, OpRISCV64ADDI, t) - v1.AuxInt = int64ToAuxInt(-1) - v1.AddArg(x) - v0.AddArg(v1) + v.reset(OpRISCV64SRAI) + v.AuxInt = int64ToAuxInt(63) + v0 := b.NewValue0(v.Pos, OpRISCV64NEG, t) + v0.AddArg(x) v.AddArg(v0) return true } |