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[InstCombine] Canonicalize (X +/- Y) & Y into ~X & Y when Y is a power of 2 #67915

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Merged
merged 4 commits into from
Oct 12, 2023
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[InstCombine] Canonicalize (X +/- Y) & Y into ~X & Y when Y is a power of 2 #67915

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c4ce28c
[InstCombine] Canonicalize `(X +/- Y) & Y` into `~X & Y` when Y is a …
dtcxzyw Oct 1, 2023
f53f23b
Merge branch 'main' into canonicalize-and-addsub-power2
dtcxzyw Oct 5, 2023
b64ca5b
fixup! [InstCombine] Canonicalize `(X +/- Y) & Y` into `~X & Y` when …
dtcxzyw Oct 6, 2023
716b677
Merge branch 'main' into canonicalize-and-addsub-power2
dtcxzyw Oct 6, 2023
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8 changes: 8 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2250,6 +2250,14 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
return SelectInst::Create(Cmp, ConstantInt::getNullValue(Ty), Y);
}

// Canonicalize:
// (X +/- Y) & Y --> ~X & Y when Y is a power of 2.
if (match(&I, m_c_And(m_Value(Y), m_OneUse(m_CombineOr(
m_c_Add(m_Value(X), m_Deferred(Y)),
m_Sub(m_Value(X), m_Deferred(Y)))))) &&
isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, /*Depth*/ 0, &I))
return BinaryOperator::CreateAnd(Builder.CreateNot(X), Y);

const APInt *C;
if (match(Op1, m_APInt(C))) {
const APInt *XorC;
Expand Down
44 changes: 40 additions & 4 deletions llvm/test/Transforms/InstCombine/and.ll
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Expand Up @@ -1595,8 +1595,8 @@ define <2 x i8> @flip_masked_bit_uniform(<2 x i8> %A) {

define <2 x i8> @flip_masked_bit_undef(<2 x i8> %A) {
; CHECK-LABEL: @flip_masked_bit_undef(
; CHECK-NEXT: [[B:%.*]] = add <2 x i8> [[A:%.*]], <i8 16, i8 undef>
; CHECK-NEXT: [[C:%.*]] = and <2 x i8> [[B]], <i8 16, i8 undef>
; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i8> [[A:%.*]], <i8 -1, i8 -1>
; CHECK-NEXT: [[C:%.*]] = and <2 x i8> [[TMP1]], <i8 16, i8 undef>
; CHECK-NEXT: ret <2 x i8> [[C]]
;
%B = add <2 x i8> %A, <i8 16, i8 undef>
Expand All @@ -1606,8 +1606,8 @@ define <2 x i8> @flip_masked_bit_undef(<2 x i8> %A) {

define <2 x i8> @flip_masked_bit_nonuniform(<2 x i8> %A) {
; CHECK-LABEL: @flip_masked_bit_nonuniform(
; CHECK-NEXT: [[B:%.*]] = add <2 x i8> [[A:%.*]], <i8 16, i8 4>
; CHECK-NEXT: [[C:%.*]] = and <2 x i8> [[B]], <i8 16, i8 4>
; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i8> [[A:%.*]], <i8 -1, i8 -1>
; CHECK-NEXT: [[C:%.*]] = and <2 x i8> [[TMP1]], <i8 16, i8 4>
; CHECK-NEXT: ret <2 x i8> [[C]]
;
%B = add <2 x i8> %A, <i8 16, i8 4>
Expand Down Expand Up @@ -2546,3 +2546,39 @@ define i32 @and_zext_eq_zero(i32 %A, i32 %C) {
%5 = and i32 %2, %4
ret i32 %5
}

define i32 @canonicalize_and_add_power2_or_zero(i32 %x, i32 %y) {
; CHECK-LABEL: @canonicalize_and_add_power2_or_zero(
; CHECK-NEXT: [[NY:%.*]] = sub i32 0, [[Y:%.*]]
; CHECK-NEXT: [[P2:%.*]] = and i32 [[NY]], [[Y]]
; CHECK-NEXT: call void @use32(i32 [[P2]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], -1
; CHECK-NEXT: [[AND:%.*]] = and i32 [[P2]], [[TMP1]]
; CHECK-NEXT: ret i32 [[AND]]
;
%ny = sub i32 0, %y
%p2 = and i32 %y, %ny
call void @use32(i32 %p2) ; keep p2

%val = add i32 %x, %p2
%and = and i32 %val, %p2
ret i32 %and
}

define i32 @canonicalize_and_sub_power2_or_zero(i32 %x, i32 %y) {
; CHECK-LABEL: @canonicalize_and_sub_power2_or_zero(
; CHECK-NEXT: [[NY:%.*]] = sub i32 0, [[Y:%.*]]
; CHECK-NEXT: [[P2:%.*]] = and i32 [[NY]], [[Y]]
; CHECK-NEXT: call void @use32(i32 [[P2]])
; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], -1
; CHECK-NEXT: [[AND:%.*]] = and i32 [[P2]], [[TMP1]]
; CHECK-NEXT: ret i32 [[AND]]
;
%ny = sub i32 0, %y
%p2 = and i32 %y, %ny
call void @use32(i32 %p2) ; keep p2

%val = sub i32 %x, %p2
%and = and i32 %val, %p2
ret i32 %and
}