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[InstCombine] Simplify 'xor' to 'or' if no common bits are set.

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Summary:
In order to get the whole fold as specified in [[ https://bugs.llvm.org/show_bug.cgi?id=6773 | PR6773 ]],
let's first handle the simple straight-forward things.
Let's start with the `and` -> `or` simplification.

The one obvious thing missing here: the constant mask is not handled.
I have an idea how to handle it, but it will require some thinking,
and is not strictly required here, so i've left that for later.

https://rise4fun.com/Alive/Pkmg

Reviewers: spatel, craig.topper, eli.friedman, jingyue

Reviewed By: spatel

Subscribers: llvm-commits

Was reviewed as part of https://reviews.llvm.org/D45631

llvm-svn: 330103
This commit is contained in:
Roman Lebedev 2018-04-15 18:59:44 +00:00
parent 23340b5f63
commit afc2c5afb5
3 changed files with 17 additions and 16 deletions
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4
lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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@ -2446,6 +2446,10 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
if (Value *V = SimplifyBSwap(I, Builder))
return replaceInstUsesWith(I, V);
// A^B --> A|B iff A and B have no bits set in common.
if (haveNoCommonBitsSet(Op0, Op1, DL, &AC, &I, &DT))
return BinaryOperator::CreateOr(Op0, Op1);
// Apply DeMorgan's Law for 'nand' / 'nor' logic with an inverted operand.
Value *X, *Y;

7
test/Transforms/InstCombine/logical-select.ll
View File

@ -399,11 +399,8 @@ define i1 @bools_multi_uses1(i1 %a, i1 %b, i1 %c) {
define i1 @bools_multi_uses2(i1 %a, i1 %b, i1 %c) {
; CHECK-LABEL: @bools_multi_uses2(
; CHECK-NEXT: [[NOT:%.*]] = xor i1 [[C:%.*]], true
; CHECK-NEXT: [[AND1:%.*]] = and i1 [[NOT]], [[A:%.*]]
; CHECK-NEXT: [[AND2:%.*]] = and i1 [[C]], [[B:%.*]]
; CHECK-NEXT: [[ADD:%.*]] = xor i1 [[AND1]], [[AND2]]
; CHECK-NEXT: ret i1 [[ADD]]
; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]]
; CHECK-NEXT: ret i1 [[TMP1]]
;
%not = xor i1 %c, -1
%and1 = and i1 %not, %a

22
test/Transforms/InstCombine/masked-merge-xor.ll
View File

@ -21,7 +21,7 @@ define i32 @p(i32 %x, i32 %y, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND]], [[AND1]]
; CHECK-NEXT: ret i32 [[RET]]
;
%and = and i32 %x, %m
@ -36,7 +36,7 @@ define <2 x i32> @p_splatvec(<2 x i32> %x, <2 x i32> %y, <2 x i32> %m) {
; CHECK-NEXT: [[AND:%.*]] = and <2 x i32> [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor <2 x i32> [[M]], <i32 -1, i32 -1>
; CHECK-NEXT: [[AND1:%.*]] = and <2 x i32> [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor <2 x i32> [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or <2 x i32> [[AND]], [[AND1]]
; CHECK-NEXT: ret <2 x i32> [[RET]]
;
%and = and <2 x i32> %x, %m
@ -51,7 +51,7 @@ define <3 x i32> @p_vec_undef(<3 x i32> %x, <3 x i32> %y, <3 x i32> %m) {
; CHECK-NEXT: [[AND:%.*]] = and <3 x i32> [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor <3 x i32> [[M]], <i32 -1, i32 undef, i32 -1>
; CHECK-NEXT: [[AND1:%.*]] = and <3 x i32> [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor <3 x i32> [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or <3 x i32> [[AND]], [[AND1]]
; CHECK-NEXT: ret <3 x i32> [[RET]]
;
%and = and <3 x i32> %x, %m
@ -129,7 +129,7 @@ define i32 @p_commutative0(i32 %x, i32 %y, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[M:%.*]], [[X:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND]], [[AND1]]
; CHECK-NEXT: ret i32 [[RET]]
;
%and = and i32 %m, %x ; swapped order
@ -145,7 +145,7 @@ define i32 @p_commutative1(i32 %x, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[Y]], [[NEG]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND]], [[AND1]]
; CHECK-NEXT: ret i32 [[RET]]
;
%y = call i32 @gen32()
@ -161,7 +161,7 @@ define i32 @p_commutative2(i32 %x, i32 %y, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND1]], [[AND]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND1]], [[AND]]
; CHECK-NEXT: ret i32 [[RET]]
;
%and = and i32 %x, %m
@ -177,7 +177,7 @@ define i32 @p_commutative3(i32 %x, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[M:%.*]], [[X:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[Y]], [[NEG]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND]], [[AND1]]
; CHECK-NEXT: ret i32 [[RET]]
;
%y = call i32 @gen32()
@ -193,7 +193,7 @@ define i32 @p_commutative4(i32 %x, i32 %y, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[M:%.*]], [[X:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND1]], [[AND]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND1]], [[AND]]
; CHECK-NEXT: ret i32 [[RET]]
;
%and = and i32 %m, %x ; swapped order
@ -209,7 +209,7 @@ define i32 @p_commutative5(i32 %x, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[Y]], [[NEG]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND1]], [[AND]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND1]], [[AND]]
; CHECK-NEXT: ret i32 [[RET]]
;
%y = call i32 @gen32()
@ -226,7 +226,7 @@ define i32 @p_commutative6(i32 %x, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[M:%.*]], [[X:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[Y]], [[NEG]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND1]], [[AND]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND1]], [[AND]]
; CHECK-NEXT: ret i32 [[RET]]
;
%y = call i32 @gen32()
@ -263,7 +263,7 @@ define i32 @n0_oneuse(i32 %x, i32 %y, i32 %m) {
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], [[M:%.*]]
; CHECK-NEXT: [[NEG:%.*]] = xor i32 [[M]], -1
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[NEG]], [[Y:%.*]]
; CHECK-NEXT: [[RET:%.*]] = xor i32 [[AND]], [[AND1]]
; CHECK-NEXT: [[RET:%.*]] = or i32 [[AND]], [[AND1]]
; CHECK-NEXT: call void @use32(i32 [[AND]])
; CHECK-NEXT: call void @use32(i32 [[NEG]])
; CHECK-NEXT: call void @use32(i32 [[AND1]])