Fix x86 fast-isel's cmp+branch folding to avoid folding when the
comparison is in a different basic block from the branch. In such
cases, the comparison's operands may not have initialized virtual
registers available.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111709 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index b7341f9..0c70eec 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -960,9 +960,11 @@
MachineBasicBlock *TrueMBB = FuncInfo.MBBMap[BI->getSuccessor(0)];
MachineBasicBlock *FalseMBB = FuncInfo.MBBMap[BI->getSuccessor(1)];
- // Fold the common case of a conditional branch with a comparison.
+ // Fold the common case of a conditional branch with a comparison
+ // in the same block (values defined on other blocks may not have
+ // initialized registers).
if (const CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition())) {
- if (CI->hasOneUse()) {
+ if (CI->hasOneUse() && CI->getParent() == I->getParent()) {
EVT VT = TLI.getValueType(CI->getOperand(0)->getType());
// Try to take advantage of fallthrough opportunities.