[PATCH] D48369: [CodeGen] Make block removal order deterministic in CodeGenPrepare
David Stenberg via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 27 01:23:55 PDT 2018
dstenb updated this revision to Diff 153018.
dstenb added a comment.
Use `pop_back_val()` for getting the items from the worklist.
https://reviews.llvm.org/D48369
Files:
lib/CodeGen/CodeGenPrepare.cpp
Index: lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- lib/CodeGen/CodeGenPrepare.cpp
+++ lib/CodeGen/CodeGenPrepare.cpp
@@ -462,7 +462,10 @@
if (!DisableBranchOpts) {
MadeChange = false;
- SmallPtrSet<BasicBlock*, 8> WorkList;
+ // Use a set vector to get deterministic iteration order. The order the
+ // blocks are removed may affect whether or not PHI nodes in successors
+ // are removed.
+ SmallSetVector<BasicBlock*, 8> WorkList;
for (BasicBlock &BB : F) {
SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
MadeChange |= ConstantFoldTerminator(&BB, true);
@@ -477,8 +480,7 @@
// Delete the dead blocks and any of their dead successors.
MadeChange |= !WorkList.empty();
while (!WorkList.empty()) {
- BasicBlock *BB = *WorkList.begin();
- WorkList.erase(BB);
+ BasicBlock *BB = WorkList.pop_back_val();
SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
DeleteDeadBlock(BB);
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