[PATCH] D78157: [AArch64InstrInfo] Ignore debug insts in areCFlagsAccessedBetweenInstrs
Vedant Kumar via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 14 15:12:39 PDT 2020
vsk created this revision.
vsk added reviewers: t.p.northover, eastig, paquette.
Herald added subscribers: danielkiss, hiraditya, kristof.beyls.
Herald added a project: LLVM.
Fix an issue where the presence of debug info could disable a peephole
optimization due to areCFlagsAccessedBetweenInstrs returning the wrong
result.
In test/CodeGen/AArch64/arm64-csel.ll, the issue was found in the
function @foo5, in which the first compare could successfully be
optimized but not the second.
Depends on D78156 <https://reviews.llvm.org/D78156>.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D78157
Files:
llvm/lib/CodeGen/PeepholeOptimizer.cpp
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
llvm/test/CodeGen/AArch64/arm64-csel.ll
Index: llvm/test/CodeGen/AArch64/arm64-csel.ll
===================================================================
--- llvm/test/CodeGen/AArch64/arm64-csel.ll
+++ llvm/test/CodeGen/AArch64/arm64-csel.ll
@@ -1,4 +1,4 @@
-; RUN: llc -O3 < %s | FileCheck %s
+; RUN: llc -debugify-and-strip-all-safe -O3 < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n32:64"
target triple = "arm64-unknown-unknown"
Index: llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -1186,7 +1186,8 @@
// We iterate backward starting \p To until we hit \p From.
for (--To; To != From; --To) {
const MachineInstr &Instr = *To;
-
+ if (Instr.isDebugInstr())
+ continue;
if (((AccessToCheck & AK_Write) &&
Instr.modifiesRegister(AArch64::NZCV, TRI)) ||
((AccessToCheck & AK_Read) && Instr.readsRegister(AArch64::NZCV, TRI)))
Index: llvm/lib/CodeGen/PeepholeOptimizer.cpp
===================================================================
--- llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -616,6 +616,7 @@
// Attempt to optimize the comparison instruction.
LLVM_DEBUG(dbgs() << "Attempting to optimize compare: " << MI);
if (TII->optimizeCompareInstr(MI, SrcReg, SrcReg2, CmpMask, CmpValue, MRI)) {
+ LLVM_DEBUG(dbgs() << " -> Successfully optimized compare!\n");
++NumCmps;
return true;
}
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