Transforms: Don't create bad branch weights when folding a switch
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.
llvm-svn: 196845
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 2768041..8a15c7c 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -127,8 +127,10 @@
// 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;