[PATCH] D98600: [X86][FastISel] Fix with.overflow eflags clobber (PR49587)

[Nikita Popov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG7669455df49e: [X86][FastISel] Fix with.overflow eflags clobber (PR49587) (authored by nikic).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98600/new/

https://reviews.llvm.org/D98600

Files:
  llvm/lib/Target/X86/X86FastISel.cpp
  llvm/test/CodeGen/X86/pr49587.ll


Index: llvm/test/CodeGen/X86/pr49587.ll
===================================================================
--- llvm/test/CodeGen/X86/pr49587.ll
+++ llvm/test/CodeGen/X86/pr49587.ll
@@ -5,10 +5,11 @@
 ; CHECK-LABEL: test:
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:    subq $1, %rdi
-; CHECK-NEXT:    setb %al
+; CHECK-NEXT:    setb %cl
 ; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    testb $1, %cl
 ; CHECK-NEXT:    movl %eax, {{[-0-9]+}}(%r{{[sb]}}p) # 4-byte Spill
-; CHECK-NEXT:    jb .LBB0_2
+; CHECK-NEXT:    jne .LBB0_2
 ; CHECK-NEXT:  # %bb.1: # %no_overflow
 ; CHECK-NEXT:    movl $1, %eax
 ; CHECK-NEXT:    movl %eax, {{[-0-9]+}}(%r{{[sb]}}p) # 4-byte Spill
Index: llvm/lib/Target/X86/X86FastISel.cpp
===================================================================
--- llvm/lib/Target/X86/X86FastISel.cpp
+++ llvm/lib/Target/X86/X86FastISel.cpp
@@ -284,6 +284,14 @@
       return false;
   }
 
+  // Make sure no potentially eflags clobbering phi moves can be inserted in
+  // between.
+  auto HasPhis = [](const BasicBlock *Succ) {
+    return !llvm::empty(Succ->phis());
+  };
+  if (I->isTerminator() && llvm::any_of(successors(I), HasPhis))
+    return false;
+
   CC = TmpCC;
   return true;
 }


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