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InstCombine: Also turn selects fed by an and into arithmetic when the types don't match.
Inserting a zext or trunc is sufficient. This pattern is somewhat common in LLVM's pointer mangling code. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185270 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -662,7 +662,7 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
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ConstantInt *FalseVal,
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InstCombiner::BuilderTy *Builder) {
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const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
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if (!IC || !IC->isEquality())
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if (!IC || !IC->isEquality() || !SI.getType()->isIntegerTy())
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return 0;
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if (!match(IC->getOperand(1), m_Zero()))
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@ -670,8 +670,7 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
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ConstantInt *AndRHS;
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Value *LHS = IC->getOperand(0);
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if (LHS->getType() != SI.getType() ||
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!match(LHS, m_And(m_Value(), m_ConstantInt(AndRHS))))
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if (!match(LHS, m_And(m_Value(), m_ConstantInt(AndRHS))))
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return 0;
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// If both select arms are non-zero see if we have a select of the form
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@ -705,7 +704,13 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
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unsigned ValZeros = ValC->getValue().logBase2();
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unsigned AndZeros = AndRHS->getValue().logBase2();
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Value *V = LHS;
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// If types don't match we can still convert the select by introducing a zext
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// or a trunc of the 'and'. The trunc case requires that all of the truncated
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// bits are zero, we can figure that out by looking at the 'and' mask.
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if (AndZeros >= ValC->getBitWidth())
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return 0;
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Value *V = Builder->CreateZExtOrTrunc(LHS, SI.getType());
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if (ValZeros > AndZeros)
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V = Builder->CreateShl(V, ValZeros - AndZeros);
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else if (ValZeros < AndZeros)
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@ -985,3 +985,39 @@ define i32 @select_icmp_ne_0_and_8_or_1073741824(i8 %x, i32 %y) {
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%select = select i1 %cmp, i32 %y, i32 %or
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ret i32 %select
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}
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define i32 @test65(i64 %x) {
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%1 = and i64 %x, 16
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%2 = icmp ne i64 %1, 0
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%3 = select i1 %2, i32 40, i32 42
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ret i32 %3
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; CHECK: @test65
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; CHECK: and i64 %x, 16
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; CHECK: trunc i64 %1 to i32
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; CHECK: lshr exact i32 %2, 3
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; CHECK: xor i32 %3, 42
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}
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define i32 @test66(i64 %x) {
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%1 = and i64 %x, 4294967296
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%2 = icmp ne i64 %1, 0
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%3 = select i1 %2, i32 40, i32 42
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ret i32 %3
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; CHECK: @test66
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; CHECK: select
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}
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define i32 @test67(i16 %x) {
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%1 = and i16 %x, 4
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%2 = icmp ne i16 %1, 0
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%3 = select i1 %2, i32 40, i32 42
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ret i32 %3
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; CHECK: @test67
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; CHECK: and i16 %x, 4
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; CHECK: zext i16 %1 to i32
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; CHECK: lshr exact i32 %2, 1
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; CHECK: xor i32 %3, 42
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}
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