[PATCH] D78156: [AArch64ConditionalCompares] Ignore debug insts in findConvertibleCompare

[Vedant Kumar via Phabricator via llvm-commits]

vsk created this revision.
vsk added reviewers: t.p.northover, paquette, aemerson.
Herald added subscribers: danielkiss, hiraditya, kristof.beyls.
Herald added a project: LLVM.

Fix an issue where the presence of debug info could disable the ccmp
optimization due to findConvertibleCompare failing too early (the error
is "Can't create ccmp with multiple uses", where the "use" is a
DBG_VALUE inst).

Depends on D78151 <https://reviews.llvm.org/D78151>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78156

Files:
  llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
  llvm/test/CodeGen/AArch64/arm64-ccmp.ll


Index: llvm/test/CodeGen/AArch64/arm64-ccmp.ll
===================================================================
--- llvm/test/CodeGen/AArch64/arm64-ccmp.ll
+++ llvm/test/CodeGen/AArch64/arm64-ccmp.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -mcpu=cyclone -verify-machineinstrs -aarch64-enable-ccmp -aarch64-stress-ccmp | FileCheck %s
+; RUN: llc < %s -debugify-and-strip-all-safe -mcpu=cyclone -verify-machineinstrs -aarch64-enable-ccmp -aarch64-stress-ccmp | FileCheck %s
 target triple = "arm64-apple-ios"
 
 ; CHECK: single_same
Index: llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
+++ llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
@@ -318,6 +318,7 @@
   // Now find the instruction controlling the terminator.
   for (MachineBasicBlock::iterator B = MBB->begin(); I != B;) {
     --I;
+    I = skipDebugInstructionsBackward(I, MBB->begin());
     assert(!I->isTerminator() && "Spurious terminator");
     switch (I->getOpcode()) {
     // cmp is an alias for subs with a dead destination register.


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