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Reinstate this optimization, but without the miscompile. Thanks to Bill for

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tracking down that this was breaking llvm-gcc bootstrap on Linux.

llvm-svn: 54394
This commit is contained in:
Nick Lewycky 2008-08-06 04:54:03 +00:00
parent 1854852a75
commit 0bf3c812d2
2 changed files with 25 additions and 0 deletions
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15
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -3586,6 +3586,21 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
}
}
{ // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (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 && LHSCC == ICmpInst::ICMP_ULT &&
C1->getValue().isPowerOf2()) {
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
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@ -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
}