[InstCombine] Fold ((C1 OP zext(X)) & C2) -> zext((C1 OP X) & C2)
This further extends r292179 to support additional binary operators beyond subtraction. llvm-svn: 292238
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@ -1331,21 +1331,6 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
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if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
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return BinaryOperator::CreateAnd(V, AndRHS);
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// ((C1-zext(X)) & C2) -> zext((C1-X) & C2) if C2 fits in the bitwidth
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// of X.
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if (auto *ZI = dyn_cast<ZExtInst>(Op0RHS)) {
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auto *X = ZI->getOperand(0);
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ConstantInt *C1;
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if (match(Op0LHS, m_ConstantInt(C1)) &&
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AndRHSMask.isIntN(X->getType()->getScalarSizeInBits())) {
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auto *TruncC1 = ConstantExpr::getTrunc(C1, X->getType());
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auto *Sub = Builder->CreateSub(TruncC1, X);
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auto *TruncC2 = ConstantExpr::getTrunc(AndRHS, X->getType());
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auto *And = Builder->CreateAnd(Sub, TruncC2);
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return new ZExtInst(And, I.getType());
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}
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}
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// -x & 1 -> x & 1
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if (AndRHSMask == 1 && match(Op0LHS, m_Zero()))
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return BinaryOperator::CreateAnd(Op0RHS, AndRHS);
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@ -1376,6 +1361,34 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
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break;
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}
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// ((C1 OP zext(X)) & C2) -> zext((C1-X) & C2) if C2 fits in the bitwidth
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// of X and OP behaves well when given trunc(C1) and X.
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switch (Op0I->getOpcode()) {
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default:
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break;
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case Instruction::Xor:
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case Instruction::Or:
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case Instruction::Mul:
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case Instruction::Add:
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case Instruction::Sub:
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Value *X;
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ConstantInt *C1;
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if (match(Op0I, m_BinOp(m_ZExt(m_Value(X)), m_ConstantInt(C1))) ||
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match(Op0I, m_BinOp(m_ConstantInt(C1), m_ZExt(m_Value(X))))) {
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if (AndRHSMask.isIntN(X->getType()->getScalarSizeInBits())) {
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auto *TruncC1 = ConstantExpr::getTrunc(C1, X->getType());
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Value *BinOp;
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if (isa<ZExtInst>(Op0LHS))
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BinOp = Builder->CreateBinOp(Op0I->getOpcode(), X, TruncC1);
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else
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BinOp = Builder->CreateBinOp(Op0I->getOpcode(), TruncC1, X);
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auto *TruncC2 = ConstantExpr::getTrunc(AndRHS, X->getType());
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auto *And = Builder->CreateAnd(BinOp, TruncC2);
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return new ZExtInst(And, I.getType());
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}
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}
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}
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if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
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if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
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return Res;
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@ -436,3 +436,49 @@ define i64 @test35(i32 %X) {
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%res = and i64 %zsub, 240
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ret i64 %res
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}
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define i64 @test36(i32 %X) {
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; CHECK-LABEL: @test36(
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; CHECK-NEXT: %[[sub:.*]] = add i32 %X, 7
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; CHECK-NEXT: %[[and:.*]] = and i32 %[[sub]], 240
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; CHECK-NEXT: %[[cst:.*]] = zext i32 %[[and]] to i64
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; CHECK-NEXT: ret i64 %[[cst]]
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%zext = zext i32 %X to i64
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%zsub = add i64 %zext, 7
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%res = and i64 %zsub, 240
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ret i64 %res
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}
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define i64 @test37(i32 %X) {
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; CHECK-LABEL: @test37(
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; CHECK-NEXT: %[[sub:.*]] = mul i32 %X, 7
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; CHECK-NEXT: %[[and:.*]] = and i32 %[[sub]], 240
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; CHECK-NEXT: %[[cst:.*]] = zext i32 %[[and]] to i64
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; CHECK-NEXT: ret i64 %[[cst]]
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%zext = zext i32 %X to i64
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%zsub = mul i64 %zext, 7
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%res = and i64 %zsub, 240
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ret i64 %res
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}
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define i64 @test38(i32 %X) {
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; CHECK-LABEL: @test38(
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; CHECK-NEXT: %[[and:.*]] = and i32 %X, 240
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; CHECK-NEXT: %[[cst:.*]] = zext i32 %[[and]] to i64
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; CHECK-NEXT: ret i64 %[[cst]]
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%zext = zext i32 %X to i64
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%zsub = xor i64 %zext, 7
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%res = and i64 %zsub, 240
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ret i64 %res
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}
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define i64 @test39(i32 %X) {
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; CHECK-LABEL: @test39(
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; CHECK-NEXT: %[[and:.*]] = and i32 %X, 240
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; CHECK-NEXT: %[[cst:.*]] = zext i32 %[[and]] to i64
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; CHECK-NEXT: ret i64 %[[cst]]
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%zext = zext i32 %X to i64
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%zsub = or i64 %zext, 7
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%res = and i64 %zsub, 240
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ret i64 %res
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}
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