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Check loop exit predicate properly while eliminating one iteration loop.

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This patch fixes PR 2869


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57369 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2008-10-10 22:02:57 +00:00
parent 875314bb52
commit fc19fbd2ca
2 changed files with 81 additions and 13 deletions
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28
lib/Transforms/Scalar/LoopIndexSplit.cpp
View File

@ -585,16 +585,7 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
// only when index variable is equal to split value.
IndVar->replaceAllUsesWith(SD.SplitValue);
// Remove Latch to Header edge.
BasicBlock *LatchSucc = NULL;
Header->removePredecessor(Latch);
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
SI != E; ++SI) {
if (Header != *SI)
LatchSucc = *SI;
}
BR->setUnconditionalDest(LatchSucc);
Instruction *LTerminator = Latch->getTerminator();
Instruction *Terminator = Header->getTerminator();
Value *ExitValue = ExitCondition->getOperand(ExitValueNum);
@ -606,12 +597,14 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
// c2 = icmp ult i32 SplitValue, ExitValue
// and i32 c1, c2
bool SignedPredicate = ExitCondition->isSignedPredicate();
CmpInst::Predicate C2Predicate = ExitCondition->getPredicate();
if (LTerminator->getOperand(0) != Header)
C2Predicate = CmpInst::getInversePredicate(C2Predicate);
Instruction *C1 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE,
SD.SplitValue, StartValue, "lisplit",
Terminator);
Instruction *C2 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
Instruction *C2 = new ICmpInst(C2Predicate,
SD.SplitValue, ExitValue, "lisplit",
Terminator);
Instruction *NSplitCond = BinaryOperator::CreateAnd(C1, C2, "lisplit",
@ -619,9 +612,18 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
SD.SplitCondition->replaceAllUsesWith(NSplitCond);
SD.SplitCondition->eraseFromParent();
// Remove Latch to Header edge.
BasicBlock *LatchSucc = NULL;
Header->removePredecessor(Latch);
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
SI != E; ++SI) {
if (Header != *SI)
LatchSucc = *SI;
}
BR->setUnconditionalDest(LatchSucc);
// Now, clear latch block. Remove instructions that are responsible
// to increment induction variable.
Instruction *LTerminator = Latch->getTerminator();
for (BasicBlock::iterator LB = Latch->begin(), LE = Latch->end();
LB != LE; ) {
Instruction *I = LB;

66
test/Transforms/LoopIndexSplit/2008-10-10-OneIteration.ll Normal file
View File

@ -0,0 +1,66 @@
; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | grep sle | count 1
; PR 2869
@w = external global [2 x [2 x i32]] ; <[2 x [2 x i32]]*> [#uses=5]
declare i32 @f() nounwind
define i32 @main() noreturn nounwind {
entry:
br label %bb1.i.outer
bb1.i.outer: ; preds = %bb5.i, %entry
%i.0.reg2mem.0.ph.i.ph = phi i32 [ 0, %entry ], [ %4, %bb5.i ] ; <i32> [#uses=3]
br label %bb1.i
bb1.i: ; preds = %bb3.i, %bb1.i.outer
%j.0.reg2mem.0.i = phi i32 [ %2, %bb3.i ], [ 0, %bb1.i.outer ] ; <i32> [#uses=3]
%0 = icmp eq i32 %i.0.reg2mem.0.ph.i.ph, %j.0.reg2mem.0.i ; <i1> [#uses=1]
br i1 %0, label %bb2.i, label %bb3.i
bb2.i: ; preds = %bb1.i
%1 = getelementptr [2 x [2 x i32]]* @w, i32 0, i32 %i.0.reg2mem.0.ph.i.ph, i32 %j.0.reg2mem.0.i ; <i32*> [#uses=1]
store i32 1, i32* %1, align 4
br label %bb3.i
bb3.i: ; preds = %bb2.i, %bb1.i
%2 = add i32 %j.0.reg2mem.0.i, 1 ; <i32> [#uses=2]
%3 = icmp sgt i32 %2, 1 ; <i1> [#uses=1]
br i1 %3, label %bb5.i, label %bb1.i
bb5.i: ; preds = %bb3.i
%4 = add i32 %i.0.reg2mem.0.ph.i.ph, 1 ; <i32> [#uses=2]
%5 = icmp sgt i32 %4, 1 ; <i1> [#uses=1]
br i1 %5, label %f.exit, label %bb1.i.outer
f.exit: ; preds = %bb5.i
%6 = load i32* getelementptr ([2 x [2 x i32]]* @w, i32 0, i32 0, i32 0), align 4 ; <i32> [#uses=1]
%7 = icmp eq i32 %6, 1 ; <i1> [#uses=1]
br i1 %7, label %bb, label %bb3
bb: ; preds = %f.exit
%8 = load i32* getelementptr ([2 x [2 x i32]]* @w, i32 0, i32 1, i32 1), align 4 ; <i32> [#uses=1]
%9 = icmp eq i32 %8, 1 ; <i1> [#uses=1]
br i1 %9, label %bb1, label %bb3
bb1: ; preds = %bb
%10 = load i32* getelementptr ([2 x [2 x i32]]* @w, i32 0, i32 1, i32 0), align 4 ; <i32> [#uses=1]
%11 = icmp eq i32 %10, 0 ; <i1> [#uses=1]
br i1 %11, label %bb2, label %bb3
bb2: ; preds = %bb1
%12 = load i32* getelementptr ([2 x [2 x i32]]* @w, i32 0, i32 0, i32 1), align 4 ; <i32> [#uses=1]
%13 = icmp eq i32 %12, 0 ; <i1> [#uses=1]
br i1 %13, label %bb4, label %bb3
bb3: ; preds = %bb2, %bb1, %bb, %f.exit
tail call void @abort() noreturn nounwind
unreachable
bb4: ; preds = %bb2
ret i32 0
}
declare void @abort() noreturn nounwind
declare void @exit(i32) noreturn nounwind