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| author | Logan Chien <loganchien@google.com> | 2011-12-16 09:08:45 +0800 |
|---|---|---|
| committer | Logan Chien <loganchien@google.com> | 2011-12-16 13:28:58 +0800 |
| commit | a1e6e241a813f81be2d2f36ab60c950ca297574b (patch) | |
| tree | cf2d7ec5c63f40e2b66d8be7737496719a0d7902 /lib/VMCore/Value.cpp | |
| parent | ac212abcc6d858470ad35ce7d660af0c1800364a (diff) | |
| parent | ddecfe54a35ffbe0675f7f33e493734fd60b2495 (diff) | |
| download | external_llvm-a1e6e241a813f81be2d2f36ab60c950ca297574b.zip external_llvm-a1e6e241a813f81be2d2f36ab60c950ca297574b.tar.gz external_llvm-a1e6e241a813f81be2d2f36ab60c950ca297574b.tar.bz2 | |
Merge with LLVM upstream r146714 (Dec 16th 2011)
Change-Id: Ied458adb08bf9a69250cbcee9b14b44d17e8701a
Diffstat (limited to 'lib/VMCore/Value.cpp')
| -rw-r--r-- | lib/VMCore/Value.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp index 291df91..a5f1918 100644 --- a/lib/VMCore/Value.cpp +++ b/lib/VMCore/Value.cpp @@ -108,6 +108,19 @@ bool Value::hasNUsesOrMore(unsigned N) const { /// isUsedInBasicBlock - Return true if this value is used in the specified /// basic block. bool Value::isUsedInBasicBlock(const BasicBlock *BB) const { + // Start by scanning over the instructions looking for a use before we start + // the expensive use iteration. + unsigned MaxBlockSize = 3; + for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + if (std::find(I->op_begin(), I->op_end(), this) != I->op_end()) + return true; + if (MaxBlockSize-- == 0) // If the block is larger fall back to use_iterator + break; + } + + if (MaxBlockSize != 0) // We scanned the entire block and found no use. + return false; + for (const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) { const Instruction *User = dyn_cast<Instruction>(*I); if (User && User->getParent() == BB) |