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author | Dan Gohman <gohman@apple.com> | 2010-03-09 01:53:33 +0000 |
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committer | Dan Gohman <gohman@apple.com> | 2010-03-09 01:53:33 +0000 |
commit | cbac7f163099fda6f3c036920404e4b87ab33d2a (patch) | |
tree | 5295b5cf0c0f8fefe128d11d63c443076160a70a | |
parent | 5b9062cb3ad2a60f18e941ac42a2382302c46f24 (diff) | |
download | external_llvm-cbac7f163099fda6f3c036920404e4b87ab33d2a.zip external_llvm-cbac7f163099fda6f3c036920404e4b87ab33d2a.tar.gz external_llvm-cbac7f163099fda6f3c036920404e4b87ab33d2a.tar.bz2 |
Make isLCSSA ignore uses in blocks not reachable from the entry block,
as LCSSA no longer transforms such uses.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98033 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Analysis/LoopInfo.cpp | 17 | ||||
-rw-r--r-- | test/Transforms/LCSSA/unreachable-use.ll | 27 |
2 files changed, 41 insertions, 3 deletions
diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index 453af5a..2139c29 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -264,6 +264,13 @@ unsigned Loop::getSmallConstantTripMultiple() const { /// isLCSSAForm - Return true if the Loop is in LCSSA form bool Loop::isLCSSAForm() const { + // Collect all the reachable blocks in the function, for fast lookups. + SmallPtrSet<BasicBlock *, 32> ReachableBBs; + BasicBlock *EntryBB = getHeader()->getParent()->begin(); + for (df_iterator<BasicBlock *> NI = df_begin(EntryBB), + NE = df_end(EntryBB); NI != NE; ++NI) + ReachableBBs.insert(*NI); + // Sort the blocks vector so that we can use binary search to do quick // lookups. SmallPtrSet<BasicBlock *, 16> LoopBBs(block_begin(), block_end()); @@ -277,9 +284,13 @@ bool Loop::isLCSSAForm() const { if (PHINode *P = dyn_cast<PHINode>(*UI)) UserBB = P->getIncomingBlock(UI); - // Check the current block, as a fast-path. Most values are used in - // the same block they are defined in. - if (UserBB != BB && !LoopBBs.count(UserBB)) + // Check the current block, as a fast-path, before checking whether + // the use is anywhere in the loop. Most values are used in the same + // block they are defined in. Also, blocks not reachable from the + // entry are special; uses in them don't need to go through PHIs. + if (UserBB != BB && + !LoopBBs.count(UserBB) && + ReachableBBs.count(UserBB)) return false; } } diff --git a/test/Transforms/LCSSA/unreachable-use.ll b/test/Transforms/LCSSA/unreachable-use.ll new file mode 100644 index 0000000..c389c9c --- /dev/null +++ b/test/Transforms/LCSSA/unreachable-use.ll @@ -0,0 +1,27 @@ +; RUN: opt < %s -lcssa -S -verify-loop-info | grep {\[%\]tmp33 = load i1\\*\\* \[%\]tmp} +; PR6546 + +; LCSSA doesn't need to transform uses in blocks not reachable +; from the entry block. + +define fastcc void @dfs() nounwind { +bb: + br label %bb44 + +bb44: + br i1 undef, label %bb7, label %bb45 + +bb7: + %tmp = bitcast i1** undef to i1** + br label %bb15 + +bb15: + br label %bb44 + +bb32: + %tmp33 = load i1** %tmp, align 8 + br label %bb45 + +bb45: + unreachable +} |