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authorBill Wendling <isanbard@gmail.com>2013-12-17 01:28:35 +0000
committerBill Wendling <isanbard@gmail.com>2013-12-17 01:28:35 +0000
commite39b15195a3607ee708be9d105b5fc591b4665dd (patch)
treea67d8c04ed0a59e045de4d41e4dd1dcb69719c90 /lib/Transforms/Vectorize
parent98872fd0fc5c254c644140d65efa4c455b60db87 (diff)
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Merging r197449:
------------------------------------------------------------------------ r197449 | arnolds | 2013-12-16 17:11:01 -0800 (Mon, 16 Dec 2013) | 7 lines LoopVectorizer: Don't if-convert constant expressions that can trap A phi node operand or an instruction operand could be a constant expression that can trap (division). Check that we don't vectorize such cases. PR16729 radar://15653590 ------------------------------------------------------------------------ git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@197453 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Vectorize')
-rw-r--r--lib/Transforms/Vectorize/LoopVectorize.cpp32
1 files changed, 31 insertions, 1 deletions
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 874db9f..5e75871 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2781,6 +2781,23 @@ void InnerLoopVectorizer::updateAnalysis() {
DEBUG(DT->verifyAnalysis());
}
+/// \brief Check whether it is safe to if-convert this phi node.
+///
+/// Phi nodes with constant expressions that can trap are not safe to if
+/// convert.
+static bool canIfConvertPHINodes(BasicBlock *BB) {
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ PHINode *Phi = dyn_cast<PHINode>(I);
+ if (!Phi)
+ return true;
+ for (unsigned p = 0, e = Phi->getNumIncomingValues(); p != e; ++p)
+ if (Constant *C = dyn_cast<Constant>(Phi->getIncomingValue(p)))
+ if (C->canTrap())
+ return false;
+ }
+ return true;
+}
+
bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
if (!EnableIfConversion)
return false;
@@ -2807,6 +2824,7 @@ bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
}
// Collect the blocks that need predication.
+ BasicBlock *Header = TheLoop->getHeader();
for (Loop::block_iterator BI = TheLoop->block_begin(),
BE = TheLoop->block_end(); BI != BE; ++BI) {
BasicBlock *BB = *BI;
@@ -2816,8 +2834,12 @@ bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
return false;
// We must be able to predicate all blocks that need to be predicated.
- if (blockNeedsPredication(BB) && !blockCanBePredicated(BB, SafePointes))
+ if (blockNeedsPredication(BB)) {
+ if (!blockCanBePredicated(BB, SafePointes))
+ return false;
+ } else if (BB != Header && !canIfConvertPHINodes(BB))
return false;
+
}
// We can if-convert this loop.
@@ -4371,6 +4393,14 @@ bool LoopVectorizationLegality::blockCanBePredicated(BasicBlock *BB,
if (it->mayWriteToMemory() || it->mayThrow())
return false;
+ // Check that we don't have a constant expression that can trap as operand.
+ for (Instruction::op_iterator OI = it->op_begin(), OE = it->op_end();
+ OI != OE; ++OI) {
+ if (Constant *C = dyn_cast<Constant>(*OI))
+ if (C->canTrap())
+ return false;
+ }
+
// The instructions below can trap.
switch (it->getOpcode()) {
default: continue;