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hwasan: Shrink outlined checks by 1 instruction.

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Turns out that we can save an instruction by folding the right shift into
the compare.

Differential Revision: https://reviews.llvm.org/D63568

llvm-svn: 363874
This commit is contained in:
Peter Collingbourne 2019-06-19 20:40:03 +00:00
parent 00b493eb4d
commit 9936afd522
2 changed files with 9 additions and 16 deletions
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19
lib/Target/AArch64/AArch64AsmPrinter.cpp
View File

@ -297,18 +297,13 @@ void AArch64AsmPrinter::EmitHwasanMemaccessSymbols(Module &M) {
.addImm(0)
.addImm(0),
*STI);
OutStreamer->EmitInstruction(MCInstBuilder(AArch64::UBFMXri)
.addReg(AArch64::X17)
.addReg(Reg)
.addImm(56)
.addImm(63),
*STI);
OutStreamer->EmitInstruction(MCInstBuilder(AArch64::SUBSWrs)
.addReg(AArch64::WZR)
.addReg(AArch64::W16)
.addReg(AArch64::W17)
.addImm(0),
*STI);
OutStreamer->EmitInstruction(
MCInstBuilder(AArch64::SUBSXrs)
.addReg(AArch64::XZR)
.addReg(AArch64::X16)
.addReg(Reg)
.addImm(AArch64_AM::getShifterImm(AArch64_AM::LSR, 56)),
*STI);
MCSymbol *HandleMismatchSym = OutContext.createTempSymbol();
OutStreamer->EmitInstruction(
MCInstBuilder(AArch64::Bcc)

6
test/CodeGen/AArch64/hwasan-check-memaccess.ll
View File

@ -38,8 +38,7 @@ declare void @llvm.hwasan.check.memaccess(i8*, i8*, i32)
; CHECK-NEXT: __hwasan_check_x0_456:
; CHECK-NEXT: ubfx x16, x0, #4, #52
; CHECK-NEXT: ldrb w16, [x9, x16]
; CHECK-NEXT: lsr x17, x0, #56
; CHECK-NEXT: cmp w16, w17
; CHECK-NEXT: cmp x16, x0, lsr #56
; CHECK-NEXT: b.ne .Ltmp0
; CHECK-NEXT: ret
; CHECK-NEXT: .Ltmp0:
@ -58,8 +57,7 @@ declare void @llvm.hwasan.check.memaccess(i8*, i8*, i32)
; CHECK-NEXT: __hwasan_check_x1_123:
; CHECK-NEXT: ubfx x16, x1, #4, #52
; CHECK-NEXT: ldrb w16, [x9, x16]
; CHECK-NEXT: lsr x17, x1, #56
; CHECK-NEXT: cmp w16, w17
; CHECK-NEXT: cmp x16, x1, lsr #56
; CHECK-NEXT: b.ne .Ltmp1
; CHECK-NEXT: ret
; CHECK-NEXT: .Ltmp1: