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| author | David Majnemer <david.majnemer@gmail.com> | 2014-05-16 16:57:04 +0000 |
|---|---|---|
| committer | David Majnemer <david.majnemer@gmail.com> | 2014-05-16 16:57:04 +0000 |
| commit | ea8d5dbf249dd6a8b21603794fe368bb82082ca4 (patch) | |
| tree | fea6c74214828c3fc554a41025023f5a3d6bebc7 /llvm/lib | |
| parent | 83c57436500fca8f09cf00e816470df46bd5ca6f (diff) | |
| download | bcm5719-llvm-ea8d5dbf249dd6a8b21603794fe368bb82082ca4.tar.gz bcm5719-llvm-ea8d5dbf249dd6a8b21603794fe368bb82082ca4.zip | |
InstSimplify: Optimize using dividend in sdiv
Summary:
The dividend in an sdiv tells us the largest and smallest possible
results. Use this fact to optimize comparisons against an sdiv with a
constant dividend.
Reviewers: nicholas
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D3795
llvm-svn: 208999
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 5421a399226..4cad81b1398 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -2020,6 +2020,10 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, APInt NegOne = APInt::getAllOnesValue(Width); if (!CI2->isZero()) Upper = NegOne.udiv(CI2->getValue()) + 1; + } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) { + // 'sdiv CI2, x' produces [-|CI2|, |CI2|]. + Upper = CI2->getValue().abs() + 1; + Lower = (-Upper) + 1; } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. APInt IntMin = APInt::getSignedMinValue(Width); |
