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[InstCombine] foldShiftIntoShiftInAnotherHandOfAndInICmp(): avoid constantexpr pitfail (PR42962)

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Instead of matching value and then blindly casting to BinaryOperator
just to get the opcode, just match instruction and do no cast.

Fixes https://bugs.llvm.org/show_bug.cgi?id=42962

llvm-svn: 368554
This commit is contained in:
Roman Lebedev 2019-08-12 11:28:02 +00:00
parent 70688517d3
commit caf7add21b
2 changed files with 17 additions and 6 deletions
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11
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -3312,10 +3312,10 @@ foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst &I, const SimplifyQuery SQ,
// Look for an 'and' of two (opposite) logical shifts.
// Pick the single-use shift as XShift.
Value *XShift, *YShift;
Instruction *XShift, *YShift;
if (!match(I.getOperand(0),
m_c_And(m_CombineAnd(m_AnyLogicalShift, m_Value(XShift)),
m_CombineAnd(m_AnyLogicalShift, m_Value(YShift)))))
m_c_And(m_CombineAnd(m_AnyLogicalShift, m_Instruction(XShift)),
m_CombineAnd(m_AnyLogicalShift, m_Instruction(YShift)))))
return nullptr;
// If YShift is a 'lshr', swap the shifts around.
@ -3323,9 +3323,8 @@ foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst &I, const SimplifyQuery SQ,
std::swap(XShift, YShift);
// The shifts must be in opposite directions.
Instruction::BinaryOps XShiftOpcode =
cast<BinaryOperator>(XShift)->getOpcode();
if (XShiftOpcode == cast<BinaryOperator>(YShift)->getOpcode())
auto XShiftOpcode = XShift->getOpcode();
if (XShiftOpcode == YShift->getOpcode())
return nullptr; // Do not care about same-direction shifts here.
Value *X, *XShAmt, *Y, *YShAmt;

12
test/Transforms/InstCombine/shift-amount-reassociation-in-bittest.ll
View File

@ -667,3 +667,15 @@ define <2 x i1> @n38_overshift(<2 x i32> %x, <2 x i32> %y) {
%t3 = icmp ne <2 x i32> %t2, <i32 0, i32 0>
ret <2 x i1> %t3
}
; As usual, don't crash given constantexpr's :/
@f.a = internal global i16 0
define i1 @constantexpr() {
entry:
%0 = load i16, i16* @f.a
%shr = ashr i16 %0, 1
%shr1 = ashr i16 %shr, zext (i1 icmp ne (i16 ptrtoint (i16* @f.a to i16), i16 1) to i16)
%and = and i16 %shr1, 1
%tobool = icmp ne i16 %and, 0
ret i1 %tobool
}