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Merging r226023:

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r226023 | majnemer | 2015-01-14 11:26:56 -0800 (Wed, 14 Jan 2015) | 3 lines

InstCombine: Don't take A-B<0 into A<B if A-B has other uses

This fixes PR22226.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_36@226059 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hans Wennborg
2015-01-14 23:14:47 +00:00
parent 96da76c014
commit 97ae37b5f3
2 changed files with 42 additions and 25 deletions
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lib/Transforms/InstCombine/InstCombineCompares.cpp
+27 -25
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@@ -2686,33 +2686,35 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
return Res;
}
// (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
if (I.isEquality() && CI->isZero() &&
match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
// (icmp cond A B) if cond is equality
return new ICmpInst(I.getPredicate(), A, B);
// The following transforms are only 'worth it' if the only user of the
// subtraction is the icmp.
if (Op0->hasOneUse()) {
// (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
if (I.isEquality() && CI->isZero() &&
match(Op0, m_Sub(m_Value(A), m_Value(B))))
return new ICmpInst(I.getPredicate(), A, B);
// (icmp sgt (sub nsw A B), -1) -> (icmp sge A, B)
if (I.getPredicate() == ICmpInst::ICMP_SGT && CI->isAllOnesValue() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SGE, A, B);
// (icmp sgt (sub nsw A B), 0) -> (icmp sgt A, B)
if (I.getPredicate() == ICmpInst::ICMP_SGT && CI->isZero() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SGT, A, B);
// (icmp slt (sub nsw A B), 0) -> (icmp slt A, B)
if (I.getPredicate() == ICmpInst::ICMP_SLT && CI->isZero() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SLT, A, B);
// (icmp slt (sub nsw A B), 1) -> (icmp sle A, B)
if (I.getPredicate() == ICmpInst::ICMP_SLT && CI->isOne() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SLE, A, B);
}
// (icmp sgt (sub nsw A B), -1) -> (icmp sge A, B)
if (I.getPredicate() == ICmpInst::ICMP_SGT && CI->isAllOnesValue() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SGE, A, B);
// (icmp sgt (sub nsw A B), 0) -> (icmp sgt A, B)
if (I.getPredicate() == ICmpInst::ICMP_SGT && CI->isZero() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SGT, A, B);
// (icmp slt (sub nsw A B), 0) -> (icmp slt A, B)
if (I.getPredicate() == ICmpInst::ICMP_SLT && CI->isZero() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SLT, A, B);
// (icmp slt (sub nsw A B), 1) -> (icmp sle A, B)
if (I.getPredicate() == ICmpInst::ICMP_SLT && CI->isOne() &&
match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
return new ICmpInst(ICmpInst::ICMP_SLE, A, B);
// If we have an icmp le or icmp ge instruction, turn it into the
// appropriate icmp lt or icmp gt instruction. This allows us to rely on
// them being folded in the code below. The SimplifyICmpInst code has