[PATCH] D51829: [MachineInstr] In addRegisterKilled and addRegisterDead, don't remove operands from inline assembly instructions if they have an associated flag operand.

[Craig Topper via Phabricator via llvm-commits]

craig.topper updated this revision to Diff 164805.
craig.topper added a comment.
Herald added a subscriber: eraman.

Add the test case from the description.


Repository:
  rL LLVM

https://reviews.llvm.org/D51829

Files:
  lib/CodeGen/MachineInstr.cpp
  test/CodeGen/X86/ms-inline-asm-redundant-clobber.ll


Index: test/CodeGen/X86/ms-inline-asm-redundant-clobber.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/ms-inline-asm-redundant-clobber.ll
@@ -0,0 +1,24 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+; This used to crash due to Live Variable analysis removing the redundant eax
+; and edx clobbers, but not removing the inline asm flag operands that proceed
+; them.
+
+ at test_mem = dso_local global [16 x i8] c"UUUUUUUUUUUUUUUU", align 16
+
+; Function Attrs: nounwind uwtable
+define dso_local void @foo() local_unnamed_addr {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    #APP
+; CHECK:         clc
+; CHECK-NEXT:    cmpxchg8b {{.*}}(%rip)
+; CHECK-NEXT:    cmpxchg16b {{.*}}(%rip)
+; CHECK-NEXT:    clc
+; CHECK:         #NO_APP
+; CHECK-NEXT:    retq
+entry:
+  tail call void asm sideeffect inteldialect "clc\0A\09cmpxchg8b $0\0A\09cmpxchg16b $1\0A\09clc", "=*m,=*m,~{eax},~{edx},~{flags},~{rax},~{rdx},~{dirflag},~{fpsr},~{flags}"([16 x i8]* nonnull @test_mem, [16 x i8]* nonnull @test_mem) #1
+  ret void
+}
Index: lib/CodeGen/MachineInstr.cpp
===================================================================
--- lib/CodeGen/MachineInstr.cpp
+++ lib/CodeGen/MachineInstr.cpp
@@ -1760,7 +1760,8 @@
   // Trim unneeded kill operands.
   while (!DeadOps.empty()) {
     unsigned OpIdx = DeadOps.back();
-    if (getOperand(OpIdx).isImplicit())
+    if (getOperand(OpIdx).isImplicit() &&
+        (!isInlineAsm() || findInlineAsmFlagIdx(OpIdx) < 0))
       RemoveOperand(OpIdx);
     else
       getOperand(OpIdx).setIsKill(false);
@@ -1824,7 +1825,8 @@
   // Trim unneeded dead operands.
   while (!DeadOps.empty()) {
     unsigned OpIdx = DeadOps.back();
-    if (getOperand(OpIdx).isImplicit())
+    if (getOperand(OpIdx).isImplicit() &&
+        (!isInlineAsm() || findInlineAsmFlagIdx(OpIdx) < 0))
       RemoveOperand(OpIdx);
     else
       getOperand(OpIdx).setIsDead(false);


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