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cmd/compile: mask SLL,SRL,SRAconst shift amount

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mips SRA/SLL/SRL shift amounts are used mod 32; this change aligns the
XXXconst rules to mask the shift amount by &31.

Passes

  $ GOARCH=mips go build -toolexec 'toolstash -cmp' -a std
  $ GOARCH=mipsle go build -toolexec 'toolstash -cmp' -a std

Fixes #42587

Change-Id: I6003ebd0bc500fba4cf6fb10254e1b557bf8c48f
Reviewed-on: https://go-review.googlesource.com/c/go/+/270117
Trust: Alberto Donizetti <alb.donizetti@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Alberto Donizetti 2020-11-14 13:33:32 +01:00
parent 92c732e901
commit f2eea4c1dc
4 changed files with 27 additions and 30 deletions
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7
src/cmd/compile/internal/ssa/gen/MIPS.rules
View File

@ -567,10 +567,9 @@
(XOR x (MOVWconst [c])) => (XORconst [c] x)
(NOR x (MOVWconst [c])) => (NORconst [c] x)
(SRA x (MOVWconst [c])) && c >= 32 => (SRAconst x [31])
(SLL x (MOVWconst [c])) => (SLLconst x [c])
(SRL x (MOVWconst [c])) => (SRLconst x [c])
(SRA x (MOVWconst [c])) => (SRAconst x [c])
(SLL x (MOVWconst [c])) => (SLLconst x [c&31])
(SRL x (MOVWconst [c])) => (SRLconst x [c&31])
(SRA x (MOVWconst [c])) => (SRAconst x [c&31])
(SGT (MOVWconst [c]) x) => (SGTconst [c] x)
(SGTU (MOVWconst [c]) x) => (SGTUconst [c] x)

6
src/cmd/compile/internal/ssa/gen/MIPSOps.go
View File

@ -185,11 +185,11 @@ func init() {
// shifts
{name: "SLL", argLength: 2, reg: gp21, asm: "SLL"}, // arg0 << arg1, shift amount is mod 32
{name: "SLLconst", argLength: 1, reg: gp11, asm: "SLL", aux: "Int32"}, // arg0 << auxInt
{name: "SLLconst", argLength: 1, reg: gp11, asm: "SLL", aux: "Int32"}, // arg0 << auxInt, shift amount must be 0 through 31 inclusive
{name: "SRL", argLength: 2, reg: gp21, asm: "SRL"}, // arg0 >> arg1, unsigned, shift amount is mod 32
{name: "SRLconst", argLength: 1, reg: gp11, asm: "SRL", aux: "Int32"}, // arg0 >> auxInt, unsigned
{name: "SRLconst", argLength: 1, reg: gp11, asm: "SRL", aux: "Int32"}, // arg0 >> auxInt, shift amount must be 0 through 31 inclusive
{name: "SRA", argLength: 2, reg: gp21, asm: "SRA"}, // arg0 >> arg1, signed, shift amount is mod 32
{name: "SRAconst", argLength: 1, reg: gp11, asm: "SRA", aux: "Int32"}, // arg0 >> auxInt, signed
{name: "SRAconst", argLength: 1, reg: gp11, asm: "SRA", aux: "Int32"}, // arg0 >> auxInt, signed, shift amount must be 0 through 31 inclusive
{name: "CLZ", argLength: 1, reg: gp11, asm: "CLZ"},

29
src/cmd/compile/internal/ssa/rewriteMIPS.go
View File

@ -4431,7 +4431,7 @@ func rewriteValueMIPS_OpMIPSSLL(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]
// match: (SLL x (MOVWconst [c]))
// result: (SLLconst x [c])
// result: (SLLconst x [c&31])
for {
x := v_0
if v_1.Op != OpMIPSMOVWconst {
@ -4439,7 +4439,7 @@ func rewriteValueMIPS_OpMIPSSLL(v *Value) bool {
}
c := auxIntToInt32(v_1.AuxInt)
v.reset(OpMIPSSLLconst)
v.AuxInt = int32ToAuxInt(c)
v.AuxInt = int32ToAuxInt(c & 31)
v.AddArg(x)
return true
}
@ -4465,24 +4465,7 @@ func rewriteValueMIPS_OpMIPSSRA(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]
// match: (SRA x (MOVWconst [c]))
// cond: c >= 32
// result: (SRAconst x [31])
for {
x := v_0
if v_1.Op != OpMIPSMOVWconst {
break
}
c := auxIntToInt32(v_1.AuxInt)
if !(c >= 32) {
break
}
v.reset(OpMIPSSRAconst)
v.AuxInt = int32ToAuxInt(31)
v.AddArg(x)
return true
}
// match: (SRA x (MOVWconst [c]))
// result: (SRAconst x [c])
// result: (SRAconst x [c&31])
for {
x := v_0
if v_1.Op != OpMIPSMOVWconst {
@ -4490,7 +4473,7 @@ func rewriteValueMIPS_OpMIPSSRA(v *Value) bool {
}
c := auxIntToInt32(v_1.AuxInt)
v.reset(OpMIPSSRAconst)
v.AuxInt = int32ToAuxInt(c)
v.AuxInt = int32ToAuxInt(c & 31)
v.AddArg(x)
return true
}
@ -4516,7 +4499,7 @@ func rewriteValueMIPS_OpMIPSSRL(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]
// match: (SRL x (MOVWconst [c]))
// result: (SRLconst x [c])
// result: (SRLconst x [c&31])
for {
x := v_0
if v_1.Op != OpMIPSMOVWconst {
@ -4524,7 +4507,7 @@ func rewriteValueMIPS_OpMIPSSRL(v *Value) bool {
}
c := auxIntToInt32(v_1.AuxInt)
v.reset(OpMIPSSRLconst)
v.AuxInt = int32ToAuxInt(c)
v.AuxInt = int32ToAuxInt(c & 31)
v.AddArg(x)
return true
}

15
test/fixedbugs/issue42587.go Normal file
View File

@ -0,0 +1,15 @@
// compile
// Copyright 2020 The Go Authors. All rights reserved. Use of this
// source code is governed by a BSD-style license that can be found in
// the LICENSE file.
package p
func f() {
var i, j int
_ = func() {
i = 32
j = j>>i | len([]int{})
}
}