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[ValueTracking] Add computeKnownBits DemandedElts support to XOR instructions (PR36319)

This commit is contained in:
Simon Pilgrim 2020-03-18 19:33:41 +00:00
parent 47ce1406c8
commit 9d40292a64
2 changed files with 3 additions and 8 deletions
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4
llvm/lib/Analysis/ValueTracking.cpp
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@ -1137,8 +1137,8 @@ static void computeKnownBitsFromOperator(const Operator *I,
Known.One |= Known2.One;
break;
case Instruction::Xor: {
computeKnownBits(I->getOperand(1), Known, Depth + 1, Q);
computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q);
computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q);
// Output known-0 bits are known if clear or set in both the LHS & RHS.
APInt KnownZeroOut = (Known.Zero & Known2.Zero) | (Known.One & Known2.One);

7
llvm/test/Transforms/InstSimplify/or.ll
View File

@ -112,12 +112,7 @@ define i8 @test11(i8 %A) {
define i8 @test11v(<2 x i8> %A) {
; CHECK-LABEL: @test11v(
; CHECK-NEXT: [[B:%.*]] = or <2 x i8> [[A:%.*]], <i8 -2, i8 0>
; CHECK-NEXT: [[CV:%.*]] = xor <2 x i8> [[B]], <i8 13, i8 13>
; CHECK-NEXT: [[C:%.*]] = extractelement <2 x i8> [[CV]], i32 0
; CHECK-NEXT: [[D:%.*]] = or i8 [[C]], 1
; CHECK-NEXT: [[E:%.*]] = xor i8 [[D]], 12
; CHECK-NEXT: ret i8 [[E]]
; CHECK-NEXT: ret i8 -1
;
%B = or <2 x i8> %A, <i8 -2, i8 0>
%CV = xor <2 x i8> %B, <i8 13, i8 13>