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Fold (a < 8) && (b < 8) into (a|b) < 8 for unsigned less or greater than.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53282 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-07-09 07:29:11 +00:00
parent 1afe5c3ff8
commit 9ee863ecc0
2 changed files with 26 additions and 0 deletions
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16
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -3594,6 +3594,22 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
}
}
{ // (icmp ugt/ult A, C) & (icmp B, C) --> (icmp (A|B), C)
// where C is a power of 2
Value *A, *B;
ConstantInt *C1, *C2;
ICmpInst::Predicate LHSCC, RHSCC;
if (match(&I, m_And(m_ICmp(LHSCC, m_Value(A), m_ConstantInt(C1)),
m_ICmp(RHSCC, m_Value(B), m_ConstantInt(C2)))))
if (C1 == C2 && LHSCC == RHSCC && C1->getValue().isPowerOf2() &&
(LHSCC == ICmpInst::ICMP_ULT || LHSCC == ICmpInst::ICMP_UGT)) {
Instruction *NewOr = BinaryOperator::CreateOr(A, B);
InsertNewInstBefore(NewOr, I);
return new ICmpInst(LHSCC, NewOr, C1);
}
}
if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
// (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))

10
test/Transforms/InstCombine/2008-07-08-AndICmp.ll Normal file
View File

@ -0,0 +1,10 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep icmp | count 1
; PR2330
define i1 @foo(i32 %a, i32 %b) nounwind {
entry:
icmp ult i32 %a, 8 ; <i1>:0 [#uses=1]
icmp ult i32 %b, 8 ; <i1>:1 [#uses=1]
and i1 %1, %0 ; <i1>:2 [#uses=1]
ret i1 %2
}