From: Joel Sing <joel@sing.id.au>
Date: Sun, 15 Mar 2020 16:29:19 +0000 (+1100)
Subject: cmd/compile: use NOT pseudo-instruction for riscv64 Slicemask
X-Git-Tag: go1.15beta1~844
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=0e44c692c2b39a071257e8be24fa971e6dc05f10;p=gostls13.git

cmd/compile: use NOT pseudo-instruction for riscv64 Slicemask

Change-Id: Idefb6669d54929065f57e3bd767c91451dc3a375
Reviewed-on: https://go-review.googlesource.com/c/go/+/223562
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---

diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64.rules b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
index a4b141b4fb..fba431368b 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64.rules
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
@@ -143,7 +143,7 @@
 // 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) -> (XORI [-1] (SRAI <t> [63] (ADDI <t> [-1] x)))
+(Slicemask <t> x) -> (NOT (SRAI <t> [63] (ADDI <t> [-1] 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 692cd92cc8..a7b0ba05b9 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -4309,12 +4309,11 @@ func rewriteValueRISCV64_OpSlicemask(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
 	// match: (Slicemask <t> x)
-	// result: (XORI [-1] (SRAI <t> [63] (ADDI <t> [-1] x)))
+	// result: (NOT (SRAI <t> [63] (ADDI <t> [-1] x)))
 	for {
 		t := v.Type
 		x := v_0
-		v.reset(OpRISCV64XORI)
-		v.AuxInt = -1
+		v.reset(OpRISCV64NOT)
 		v0 := b.NewValue0(v.Pos, OpRISCV64SRAI, t)
 		v0.AuxInt = 63
 		v1 := b.NewValue0(v.Pos, OpRISCV64ADDI, t)