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

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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>
This commit is contained in:
Joel Sing 2020-04-26 04:34:34 +10:00
parent be08e10b3b
commit 9439a7d87f
3 changed files with 9 additions and 18 deletions
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4
src/cmd/compile/internal/ssa/gen/RISCV64.rules
View File

@ -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

3
src/cmd/compile/internal/ssa/gen/RISCV64Ops.go
View File

@ -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

20
src/cmd/compile/internal/ssa/rewriteRISCV64.go
View File

@ -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