utils: Fix segfault in flattencfg
v2: continue iterating through the rest of the bb
use for loop
v3: initialize FlattenCFG pass in ScalarOps
add test
v4: split off initializing flattencfg to a separate patch
add comment
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
llvm-svn: 215574
diff --git a/llvm/lib/Transforms/Utils/FlattenCFG.cpp b/llvm/lib/Transforms/Utils/FlattenCFG.cpp
index 51ead40..4eb3e3d 100644
--- a/llvm/lib/Transforms/Utils/FlattenCFG.cpp
+++ b/llvm/lib/Transforms/Utils/FlattenCFG.cpp
@@ -238,9 +238,13 @@
// Do branch inversion.
BasicBlock *CurrBlock = LastCondBlock;
bool EverChanged = false;
- while (1) {
+ for (;CurrBlock != FirstCondBlock;
+ CurrBlock = CurrBlock->getSinglePredecessor()) {
BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
+ if (!CI)
+ continue;
+
CmpInst::Predicate Predicate = CI->getPredicate();
// Canonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
if ((Predicate == CmpInst::ICMP_NE) || (Predicate == CmpInst::FCMP_ONE)) {
@@ -248,9 +252,6 @@
BI->swapSuccessors();
EverChanged = true;
}
- if (CurrBlock == FirstCondBlock)
- break;
- CurrBlock = CurrBlock->getSinglePredecessor();
}
return EverChanged;
}