diff options
| -rw-r--r-- | lib/Transforms/Utils/LoopUnrollRuntime.cpp | 23 | ||||
| -rw-r--r-- | test/Transforms/LoopUnroll/runtime-loop.ll | 6 |
2 files changed, 18 insertions, 11 deletions
diff --git a/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/lib/Transforms/Utils/LoopUnrollRuntime.cpp index 5bef091a49..a96c46ad63 100644 --- a/lib/Transforms/Utils/LoopUnrollRuntime.cpp +++ b/lib/Transforms/Utils/LoopUnrollRuntime.cpp @@ -280,17 +280,17 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI, SCEVExpander Expander(*SE, "loop-unroll"); Value *TripCount = Expander.expandCodeFor(TripCountSC, TripCountSC->getType(), PreHeaderBR); - Type *CountTy = TripCount->getType(); - BinaryOperator *ModVal = - BinaryOperator::CreateURem(TripCount, - ConstantInt::get(CountTy, Count), - "xtraiter"); - ModVal->insertBefore(PreHeaderBR); - - // Check if for no extra iterations, then jump to unrolled loop - Value *BranchVal = new ICmpInst(PreHeaderBR, - ICmpInst::ICMP_NE, ModVal, - ConstantInt::get(CountTy, 0), "lcmp"); + + IRBuilder<> B(PreHeaderBR); + Value *ModVal = B.CreateAnd(TripCount, Count - 1, "xtraiter"); + + // Check if for no extra iterations, then jump to unrolled loop. We have to + // check that the trip count computation didn't overflow when adding one to + // the backedge taken count. + Value *LCmp = B.CreateIsNotNull(ModVal, "lcmp.mod"); + Value *OverflowCheck = B.CreateIsNull(TripCount, "lcmp.overflow"); + Value *BranchVal = B.CreateOr(OverflowCheck, LCmp, "lcmp.or"); + // Branch to either the extra iterations or the unrolled loop // We will fix up the true branch label when adding loop body copies BranchInst::Create(PEnd, PEnd, BranchVal, PreHeaderBR); @@ -344,6 +344,7 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI, } // The comparison w/ the extra iteration value and branch + Type *CountTy = TripCount->getType(); Value *BranchVal = new ICmpInst(*NewBB, ICmpInst::ICMP_EQ, ModVal, ConstantInt::get(CountTy, leftOverIters), "un.tmp"); diff --git a/test/Transforms/LoopUnroll/runtime-loop.ll b/test/Transforms/LoopUnroll/runtime-loop.ll index d8bbea9f10..a14087dcdc 100644 --- a/test/Transforms/LoopUnroll/runtime-loop.ll +++ b/test/Transforms/LoopUnroll/runtime-loop.ll @@ -2,6 +2,12 @@ ; Tests for unrolling loops with run-time trip counts +; CHECK: %xtraiter = and i32 %n +; CHECK: %lcmp.mod = icmp ne i32 %xtraiter, 0 +; CHECK: %lcmp.overflow = icmp eq i32 %n, 0 +; CHECK: %lcmp.or = or i1 %lcmp.overflow, %lcmp.mod +; CHECK: br i1 %lcmp.or, label %unr.cmp + ; CHECK: unr.cmp{{.*}}: ; CHECK: for.body.unr{{.*}}: ; CHECK: for.body: |