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Transforms: Don't create bad branch weights when folding a switch

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This avoids creating branch weight metadata of length one when we fold
cases into the default of a switch instruction, which was triggering
an assert.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196845 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Justin Bogner
2013-12-10 00:13:41 +00:00
parent 4a644cc525
commit 31eaed9c6d
2 changed files with 22 additions and 2 deletions
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6
lib/Transforms/Utils/Local.cpp
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@@ -127,8 +127,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
// dest. If so, eliminate it as an explicit compare.
if (i.getCaseSuccessor() == DefaultDest) {
MDNode* MD = SI->getMetadata(LLVMContext::MD_prof);
// MD should have 2 + NumCases operands.
if (MD && MD->getNumOperands() == 2 + SI->getNumCases()) {
unsigned NCases = SI->getNumCases();
// Fold the case metadata into the default if there will be any branches
// left, unless the metadata doesn't match the switch.
if (NCases > 1 && MD && MD->getNumOperands() == 2 + NCases) {
// Collect branch weights into a vector.
SmallVector<uint32_t, 8> Weights;
for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e;