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-rw-r--r--lib/Transforms/Scalar/FlattenCFGPass.cpp24
1 files changed, 17 insertions, 7 deletions
diff --git a/lib/Transforms/Scalar/FlattenCFGPass.cpp b/lib/Transforms/Scalar/FlattenCFGPass.cpp
index 31670b1464e4..e6abf1ceb026 100644
--- a/lib/Transforms/Scalar/FlattenCFGPass.cpp
+++ b/lib/Transforms/Scalar/FlattenCFGPass.cpp
@@ -11,10 +11,12 @@
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/IR/CFG.h"
+#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
+
using namespace llvm;
#define DEBUG_TYPE "flattencfg"
@@ -52,15 +54,23 @@ FunctionPass *llvm::createFlattenCFGPass() { return new FlattenCFGPass(); }
static bool iterativelyFlattenCFG(Function &F, AliasAnalysis *AA) {
bool Changed = false;
bool LocalChange = true;
+
+ // Use block handles instead of iterating over function blocks directly
+ // to avoid using iterators invalidated by erasing blocks.
+ std::vector<WeakVH> Blocks;
+ Blocks.reserve(F.size());
+ for (auto &BB : F)
+ Blocks.push_back(&BB);
+
while (LocalChange) {
LocalChange = false;
- // Loop over all of the basic blocks and remove them if they are unneeded...
- //
- for (Function::iterator BBIt = F.begin(); BBIt != F.end();) {
- if (FlattenCFG(&*BBIt++, AA)) {
- LocalChange = true;
- }
+ // Loop over all of the basic blocks and try to flatten them.
+ for (WeakVH &BlockHandle : Blocks) {
+ // Skip blocks erased by FlattenCFG.
+ if (auto *BB = cast_or_null<BasicBlock>(BlockHandle))
+ if (FlattenCFG(BB, AA))
+ LocalChange = true;
}
Changed |= LocalChange;
}