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 845ca58..fbd8736 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 8bdb35f..8ab4abe 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
@@ -10,6 +10,9 @@
"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 db9f529..6b91c08 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -391,7 +391,8 @@
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 @@
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 @@
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
