From: Joel Sing <joel@sing.id.au>
Date: Sat, 25 Apr 2020 18:34:34 +0000 (+1000)
Subject: cmd/compile: use SEQZ pseudo instruction in RISCV64 boolean rules
X-Git-Tag: go1.15beta1~245
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=9439a7d87f90b97e00717fc0849d4460628d82d0;p=gostls13.git

cmd/compile: use SEQZ pseudo instruction in RISCV64 boolean rules

This makes the intent clearer, allows for another ellipsis and will aid
in future rewriting. While here, document boolean loads to explain register
contents.

Change-Id: I933db2813826d88819366191fbbea8fcee5e4dda
Reviewed-on: https://go-review.googlesource.com/c/go/+/230120
Reviewed-by: Keith Randall <khr@golang.org>
---

diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64.rules b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
index 845ca58b6e..fbd87360ac 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64.rules
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
@@ -414,9 +414,9 @@
 // Boolean ops; 0=false, 1=true
 (AndB ...) => (AND ...)
 (OrB  ...) => (OR  ...)
-(EqB  x y) => (XORI [1] (XOR <typ.Bool> x y))
+(EqB  x y) => (SEQZ (XOR <typ.Bool> x y))
 (NeqB ...) => (XOR ...)
-(Not  x)   => (XORI [1] x)
+(Not  ...) => (SEQZ ...)
 
 // Lowering pointer arithmetic
 // TODO: Special handling for SP offsets, like ARM
diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go b/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
index 8bdb35f95a..8ab4abe04a 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
@@ -10,6 +10,9 @@ import (
 	"fmt"
 )
 
+// Notes:
+//  - Boolean types occupy the entire register. 0=false, 1=true.
+
 // Suffixes encode the bit width of various instructions:
 //
 // D (double word) = 64 bit int
diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index db9f529bae..6b91c08628 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -391,7 +391,8 @@ func rewriteValueRISCV64(v *Value) bool {
 		v.Op = OpRISCV64LoweredNilCheck
 		return true
 	case OpNot:
-		return rewriteValueRISCV64_OpNot(v)
+		v.Op = OpRISCV64SEQZ
+		return true
 	case OpOffPtr:
 		return rewriteValueRISCV64_OpOffPtr(v)
 	case OpOr16:
@@ -913,12 +914,11 @@ func rewriteValueRISCV64_OpEqB(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (EqB x y)
-	// result: (XORI [1] (XOR <typ.Bool> x y))
+	// result: (SEQZ (XOR <typ.Bool> x y))
 	for {
 		x := v_0
 		y := v_1
-		v.reset(OpRISCV64XORI)
-		v.AuxInt = int64ToAuxInt(1)
+		v.reset(OpRISCV64SEQZ)
 		v0 := b.NewValue0(v.Pos, OpRISCV64XOR, typ.Bool)
 		v0.AddArg2(x, y)
 		v.AddArg(v0)
@@ -2132,18 +2132,6 @@ func rewriteValueRISCV64_OpNeqPtr(v *Value) bool {
 		return true
 	}
 }
-func rewriteValueRISCV64_OpNot(v *Value) bool {
-	v_0 := v.Args[0]
-	// match: (Not x)
-	// result: (XORI [1] x)
-	for {
-		x := v_0
-		v.reset(OpRISCV64XORI)
-		v.AuxInt = int64ToAuxInt(1)
-		v.AddArg(x)
-		return true
-	}
-}
 func rewriteValueRISCV64_OpOffPtr(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block