diff options
| author | Duncan Sands <baldrick@free.fr> | 2011-01-30 18:03:50 +0000 |
|---|---|---|
| committer | Duncan Sands <baldrick@free.fr> | 2011-01-30 18:03:50 +0000 |
| commit | 1895e98ef38afbe011575cc25f4889d96e37421b (patch) | |
| tree | 19f30e63e5aa7c09797f0d200d8e5935b9616bed | |
| parent | 9b108a338d544a6baf2ff087055326e301e6815d (diff) | |
Transform (X/Y)*Y into X if the division is exact. Instcombine already knows how
to do this and more, but would only do it if X/Y had only one use. Spotted as the
most common missed simplification in SPEC by my auto-simplifier, now that it knows
about nuw/nsw/exact flags. This removes a bunch of multiplications from 447.dealII
and 483.xalancbmk. It also removes a lot from tramp3d-v4, which results in much
more inlining.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124560 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/InstructionSimplify.cpp | 9 | ||||
| -rw-r--r-- | test/Transforms/InstSimplify/2010-12-20-Reassociate.ll | 18 |
2 files changed, 27 insertions, 0 deletions
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index cf50668cb0..fcbc6d50ee 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -710,6 +710,15 @@ static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD, if (match(Op1, m_One())) return Op0; + // (X / Y) * Y -> X if the division is exact. + Value *X = 0, *Y = 0; + if ((match(Op0, m_SDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y + (match(Op1, m_SDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y) + BinaryOperator *SDiv = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1); + if (SDiv->isExact()) + return X; + } + // i1 mul -> and. if (MaxRecurse && Op0->getType()->isIntegerTy(1)) if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1)) diff --git a/test/Transforms/InstSimplify/2010-12-20-Reassociate.ll b/test/Transforms/InstSimplify/2010-12-20-Reassociate.ll index 13724669d7..928442ac56 100644 --- a/test/Transforms/InstSimplify/2010-12-20-Reassociate.ll +++ b/test/Transforms/InstSimplify/2010-12-20-Reassociate.ll @@ -119,6 +119,24 @@ define i32 @sdiv3(i32 %x, i32 %y) { ; CHECK: ret i32 0 } +define i32 @sdiv4(i32 %x, i32 %y) { +; CHECK: @sdiv4 +; (X / Y) * Y -> X if the division is exact + %div = sdiv exact i32 %x, %y + %mul = mul i32 %div, %y + ret i32 %mul +; CHECK: ret i32 %x +} + +define i32 @sdiv5(i32 %x, i32 %y) { +; CHECK: @sdiv5 +; Y * (X / Y) -> X if the division is exact + %div = sdiv exact i32 %x, %y + %mul = mul i32 %y, %div + ret i32 %mul +; CHECK: ret i32 %x +} + define i32 @udiv1(i32 %x, i32 %y) { ; CHECK: @udiv1 ; (no overflow X * Y) / Y -> X |