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LoopUnrollRuntime: Check for overflow in the trip count calculation.
Fixes PR19823. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211436 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -280,17 +280,17 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
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SCEVExpander Expander(*SE, "loop-unroll");
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Value *TripCount = Expander.expandCodeFor(TripCountSC, TripCountSC->getType(),
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PreHeaderBR);
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Type *CountTy = TripCount->getType();
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BinaryOperator *ModVal =
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BinaryOperator::CreateURem(TripCount,
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ConstantInt::get(CountTy, Count),
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"xtraiter");
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ModVal->insertBefore(PreHeaderBR);
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// Check if for no extra iterations, then jump to unrolled loop
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Value *BranchVal = new ICmpInst(PreHeaderBR,
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ICmpInst::ICMP_NE, ModVal,
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ConstantInt::get(CountTy, 0), "lcmp");
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IRBuilder<> B(PreHeaderBR);
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Value *ModVal = B.CreateAnd(TripCount, Count - 1, "xtraiter");
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// Check if for no extra iterations, then jump to unrolled loop. We have to
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// check that the trip count computation didn't overflow when adding one to
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// the backedge taken count.
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Value *LCmp = B.CreateIsNotNull(ModVal, "lcmp.mod");
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Value *OverflowCheck = B.CreateIsNull(TripCount, "lcmp.overflow");
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Value *BranchVal = B.CreateOr(OverflowCheck, LCmp, "lcmp.or");
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// Branch to either the extra iterations or the unrolled loop
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// We will fix up the true branch label when adding loop body copies
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BranchInst::Create(PEnd, PEnd, BranchVal, PreHeaderBR);
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@ -344,6 +344,7 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
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}
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// The comparison w/ the extra iteration value and branch
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Type *CountTy = TripCount->getType();
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Value *BranchVal = new ICmpInst(*NewBB, ICmpInst::ICMP_EQ, ModVal,
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ConstantInt::get(CountTy, leftOverIters),
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"un.tmp");
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@ -2,6 +2,12 @@
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; Tests for unrolling loops with run-time trip counts
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; CHECK: %xtraiter = and i32 %n
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; CHECK: %lcmp.mod = icmp ne i32 %xtraiter, 0
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; CHECK: %lcmp.overflow = icmp eq i32 %n, 0
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; CHECK: %lcmp.or = or i1 %lcmp.overflow, %lcmp.mod
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; CHECK: br i1 %lcmp.or, label %unr.cmp
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; CHECK: unr.cmp{{.*}}:
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; CHECK: for.body.unr{{.*}}:
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; CHECK: for.body:
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