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Check for side effects before splitting loop.

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Patch by Jakub Staszak!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102928 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2010-05-03 18:06:58 +00:00
parent 34c3e36e63
commit 86b6f80a4c
3 changed files with 80 additions and 0 deletions
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19
lib/Transforms/Scalar/LoopIndexSplit.cpp
View File

@ -948,6 +948,25 @@ bool LoopIndexSplit::splitLoop() {
if (!IVBasedValues.count(SplitCondition->getOperand(!SVOpNum)))
return false;
// Check for side effects.
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I) {
BasicBlock *BB = *I;
assert(DT->dominates(Header, BB));
if (DT->properlyDominates(SplitCondition->getParent(), BB))
continue;
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE; ++BI) {
Instruction *Inst = BI;
if (!Inst->isSafeToSpeculativelyExecute() && !isa<PHINode>(Inst)
&& !isa<BranchInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst))
return false;
}
}
// Normalize loop conditions so that it is easier to calculate new loop
// bounds.
if (IVisGT(*ExitCondition) || IVisGE(*ExitCondition)) {

38
test/Transforms/LoopIndexSplit/PR4174-2.ll Normal file
View File

@ -0,0 +1,38 @@
; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | not grep clone
declare void @f()
define fastcc i32 @main() nounwind {
entry:
br label %bb1552
bb1552:
%j295.0.reg2mem.0 = phi i32 [ %storemerge110, %bb1669 ], [ 0, %entry ]
br label %bb1553
bb1553:
call void @f()
%tmp1628 = icmp sgt i32 %j295.0.reg2mem.0, -3
br i1 %tmp1628, label %bb1588, label %bb1616
bb1588:
br label %bb1616
bb1616:
%tmp1629 = icmp sgt i32 %j295.0.reg2mem.0, -3
br i1 %tmp1629, label %bb1649, label %bb1632
bb1632:
br label %bb1669
bb1649:
br label %bb1669
bb1669:
%storemerge110 = add i32 %j295.0.reg2mem.0, 1
%tmp1672 = icmp sgt i32 %storemerge110, 3
br i1 %tmp1672, label %bb1678, label %bb1552
bb1678:
ret i32 0
}

23
test/Transforms/LoopIndexSplit/PR4174.ll Normal file
View File

@ -0,0 +1,23 @@
; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | not grep clone
declare void @f()
define i32 @main() {
entry:
br label %head
head:
%i = phi i32 [0, %entry], [%i1, %tail]
call void @f()
%splitcond = icmp slt i32 %i, 2
br i1 %splitcond, label %yes, label %no
yes:
br label %tail
no:
br label %tail
tail:
%i1 = add i32 %i, 1
%exitcond = icmp slt i32 %i1, 4
br i1 %exitcond, label %head, label %exit
exit:
ret i32 0
}