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Fix x86 fast-isel's cmp+branch folding to avoid folding when the

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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
This commit is contained in:
Dan Gohman
2010-08-21 02:32:36 +00:00
parent bf8154a439
commit 8bef744518
2 changed files with 33 additions and 2 deletions
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6
lib/Target/X86/X86FastISel.cpp
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@@ -960,9 +960,11 @@ bool X86FastISel::X86SelectBranch(const Instruction *I) {
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.