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[InstCombine] Change order of canonicalization of ADD and AND
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Canonicalize ((x + C1) & C2) --> ((x & C2) + C1) for suitable constants
C1 and C2, instead of the other way round. This should allow more
constant ADDs to be matched as part of addressing modes for loads and
stores.

Differential Revision: https://reviews.llvm.org/D130080
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@jayfoad
jayfoad committed Aug 22, 2022
1 parent 2754ff8 commit f82c55f
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Showing 7 changed files with 46 additions and 39 deletions.
9 changes: 0 additions & 9 deletions llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
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Expand Up @@ -969,15 +969,6 @@ Instruction *InstCombinerImpl::foldAddWithConstant(BinaryOperator &Add) {
}
}

// If all bits affected by the add are included in a high-bit-mask, do the
// add before the mask op:
// (X & 0xFF00) + xx00 --> (X + xx00) & 0xFF00
if (match(Op0, m_OneUse(m_And(m_Value(X), m_APInt(C2)))) &&
C2->isNegative() && C2->isShiftedMask() && *C == (*C & *C2)) {
Value *NewAdd = Builder.CreateAdd(X, ConstantInt::get(Ty, *C));
return BinaryOperator::CreateAnd(NewAdd, ConstantInt::get(Ty, *C2));
}

return nullptr;
}

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8 changes: 8 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Expand Up @@ -1888,6 +1888,14 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
Value *NewAnd = Builder.CreateAnd(X, Op1);
return BinaryOperator::CreateXor(NewAnd, Op1);
}

// If all bits affected by the add are included in a high-bit-mask, do the
// mask op before the add. Example:
// (X + 16) & -4 --> (X & -4) + 16
if (Op0->hasOneUse() && C->isNegatedPowerOf2() && *AddC == (*AddC & *C)) {
Value *NewAnd = Builder.CreateAnd(X, Op1);
return BinaryOperator::CreateAdd(NewAnd, ConstantInt::get(Ty, *AddC));
}
}

// ((C1 OP zext(X)) & C2) -> zext((C1 OP X) & C2) if C2 fits in the
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6 changes: 5 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Expand Up @@ -2602,10 +2602,14 @@ foldRoundUpIntegerWithPow2Alignment(SelectInst &SI,
if (!match(XLowBits, m_And(m_Specific(X), m_APIntAllowUndef(LowBitMaskCst))))
return nullptr;

// Match even if the AND and ADD are swapped.
const APInt *BiasCst, *HighBitMaskCst;
if (!match(XBiasedHighBits,
m_And(m_Add(m_Specific(X), m_APIntAllowUndef(BiasCst)),
m_APIntAllowUndef(HighBitMaskCst))))
m_APIntAllowUndef(HighBitMaskCst))) &&
!match(XBiasedHighBits,
m_Add(m_And(m_Specific(X), m_APIntAllowUndef(HighBitMaskCst)),
m_APIntAllowUndef(BiasCst))))
return nullptr;

if (!LowBitMaskCst->isMask())
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18 changes: 9 additions & 9 deletions llvm/test/Transforms/InstCombine/add.ll
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Expand Up @@ -724,12 +724,12 @@ define i8 @test34(i8 %A) {
}

; If all bits affected by the add are included
; in the mask, do the add before the mask op.
; in the mask, do the mask op before the add.

define i8 @masked_add(i8 %x) {
; CHECK-LABEL: @masked_add(
; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[X:%.*]], 96
; CHECK-NEXT: [[R:%.*]] = and i8 [[TMP1]], -16
; CHECK-NEXT: [[AND:%.*]] = and i8 [[X:%.*]], -16
; CHECK-NEXT: [[R:%.*]] = add i8 [[AND]], 96
; CHECK-NEXT: ret i8 [[R]]
;
%and = and i8 %x, 240 ; 0xf0
Expand All @@ -739,8 +739,8 @@ define i8 @masked_add(i8 %x) {

define <2 x i8> @masked_add_splat(<2 x i8> %x) {
; CHECK-LABEL: @masked_add_splat(
; CHECK-NEXT: [[TMP1:%.*]] = add <2 x i8> [[X:%.*]], <i8 64, i8 64>
; CHECK-NEXT: [[R:%.*]] = and <2 x i8> [[TMP1]], <i8 -64, i8 -64>
; CHECK-NEXT: [[AND:%.*]] = and <2 x i8> [[X:%.*]], <i8 -64, i8 -64>
; CHECK-NEXT: [[R:%.*]] = add <2 x i8> [[AND]], <i8 64, i8 64>
; CHECK-NEXT: ret <2 x i8> [[R]]
;
%and = and <2 x i8> %x, <i8 192, i8 192> ; 0xc0
Expand All @@ -761,14 +761,14 @@ define i8 @not_masked_add(i8 %x) {

define i8 @masked_add_multi_use(i8 %x) {
; CHECK-LABEL: @masked_add_multi_use(
; CHECK-NEXT: [[TMP:%.*]] = add i8 [[X:%.*]], 96
; CHECK-NEXT: [[R:%.*]] = and i8 [[TMP:%.*]], -16
; CHECK-NEXT: call void @use(i8 [[X]])
; CHECK-NEXT: [[AND:%.*]] = and i8 [[X:%.*]], -16
; CHECK-NEXT: [[R:%.*]] = add i8 [[AND]], 96
; CHECK-NEXT: call void @use(i8 [[AND]])
; CHECK-NEXT: ret i8 [[R]]
;
%and = and i8 %x, -16 ; 0xf0
%r = add i8 %and, 96 ; 0x60
call void @use(i8 %x) ; extra use
call void @use(i8 %and) ; extra use
ret i8 %r
}

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32 changes: 16 additions & 16 deletions llvm/test/Transforms/InstCombine/integer-round-up-pow2-alignment.ll
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Expand Up @@ -247,8 +247,8 @@ define i8 @n9_wrong_x0(i8 %x.0, i8 %x.1) {
; CHECK-LABEL: @n9_wrong_x0(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X_0:%.*]], 15
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X_0]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X_0]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X_1:%.*]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand All @@ -263,8 +263,8 @@ define i8 @n9_wrong_x1(i8 %x.0, i8 %x.1) {
; CHECK-LABEL: @n9_wrong_x1(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X_0:%.*]], 15
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X_1:%.*]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X_1:%.*]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X_0]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand All @@ -279,8 +279,8 @@ define i8 @n9_wrong_x2(i8 %x.0, i8 %x.1) {
; CHECK-LABEL: @n9_wrong_x2(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X_1:%.*]], 15
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X_0:%.*]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X_0:%.*]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X_0]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand All @@ -297,8 +297,8 @@ define i8 @n10_wrong_low_bit_mask(i8 %x) {
; CHECK-LABEL: @n10_wrong_low_bit_mask(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X:%.*]], 31
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand Down Expand Up @@ -333,8 +333,8 @@ define i8 @n12_wrong_bias(i8 %x) {
; CHECK-LABEL: @n12_wrong_bias(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X:%.*]], 15
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X]], 32
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 32
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand Down Expand Up @@ -369,8 +369,8 @@ define i8 @n14_wrong_comparison_constant(i8 %x) {
; CHECK-LABEL: @n14_wrong_comparison_constant(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X:%.*]], 15
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 1
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand All @@ -387,8 +387,8 @@ define i8 @n15_wrong_comparison_predicate_and_constant(i8 %x) {
; CHECK-LABEL: @n15_wrong_comparison_predicate_and_constant(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X:%.*]], 14
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
;
Expand All @@ -405,8 +405,8 @@ define i8 @n16_oneuse(i8 %x) {
; CHECK-LABEL: @n16_oneuse(
; CHECK-NEXT: [[X_LOWBITS:%.*]] = and i8 [[X:%.*]], 15
; CHECK-NEXT: [[X_LOWBITS_ARE_ZERO:%.*]] = icmp eq i8 [[X_LOWBITS]], 0
; CHECK-NEXT: [[X_BIASED:%.*]] = add i8 [[X]], 16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = and i8 [[X_BIASED]], -16
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X]], -16
; CHECK-NEXT: [[X_BIASED_HIGHBITS:%.*]] = add i8 [[TMP1]], 16
; CHECK-NEXT: call void @use.i8(i8 [[X_BIASED_HIGHBITS]])
; CHECK-NEXT: [[X_ROUNDEDUP:%.*]] = select i1 [[X_LOWBITS_ARE_ZERO]], i8 [[X]], i8 [[X_BIASED_HIGHBITS]]
; CHECK-NEXT: ret i8 [[X_ROUNDEDUP]]
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8 changes: 6 additions & 2 deletions llvm/test/Transforms/InstCombine/or.ll
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Expand Up @@ -154,10 +154,14 @@ define i32 @test20(i32 %x) {
ret i32 %z
}

; TODO: This should combine to t1 + 2.
define i32 @test21(i32 %t1) {
; CHECK-LABEL: @test21(
; CHECK-NEXT: [[T1_MASK1:%.*]] = add i32 [[T1:%.*]], 2
; CHECK-NEXT: ret i32 [[T1_MASK1]]
; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[T1:%.*]], -2
; CHECK-NEXT: [[T3:%.*]] = add i32 [[TMP1]], 2
; CHECK-NEXT: [[T5:%.*]] = and i32 [[T1]], 1
; CHECK-NEXT: [[T6:%.*]] = or i32 [[T5]], [[T3]]
; CHECK-NEXT: ret i32 [[T6]]
;
%t1.mask1 = add i32 %t1, 2
%t3 = and i32 %t1.mask1, -2
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4 changes: 2 additions & 2 deletions llvm/test/Transforms/InstCombine/sub.ll
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Expand Up @@ -1490,8 +1490,8 @@ define i8 @sub_add_sub_reassoc_use2(i8 %w, i8 %x, i8 %y, i8 %z) {

define i8 @sub_mask_lowbits(i8 %x) {
; CHECK-LABEL: @sub_mask_lowbits(
; CHECK-NEXT: [[A1:%.*]] = add i8 [[X:%.*]], -108
; CHECK-NEXT: [[R:%.*]] = and i8 [[A1]], -4
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X:%.*]], -4
; CHECK-NEXT: [[R:%.*]] = add i8 [[TMP1]], -108
; CHECK-NEXT: ret i8 [[R]]
;
%a1 = add i8 %x, 148 ; 0x94
Expand Down

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