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[ConstraintElim] Pick NUWSub fix. #7925

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Merged
merged 3 commits into from
Jan 3, 2024
Merged

[ConstraintElim] Pick NUWSub fix. #7925

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b206236
[ConstraintElim] Add test case for #76713
fhahn Jan 2, 2024
59d8f40
[ConstraintElim] Add extra tests with chained subs.
fhahn Jan 2, 2024
188249f
[ConstraintElim] Replace NUWSub decomp with recursive decomp of ops.
fhahn Jan 2, 2024
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17 changes: 13 additions & 4 deletions llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,13 @@ struct Decomposition {
append_range(Vars, Other.Vars);
}

void sub(const Decomposition &Other) {
Decomposition Tmp = Other;
Tmp.mul(-1);
add(Tmp.Offset);
append_range(Vars, Tmp.Vars);
}

void mul(int64_t Factor) {
Offset = multiplyWithOverflow(Offset, Factor);
for (auto &Var : Vars)
Expand Down Expand Up @@ -542,10 +549,12 @@ static Decomposition decompose(Value *V,
return Result;
}

if (match(V, m_NUWSub(m_Value(Op0), m_ConstantInt(CI))) && canUseSExt(CI))
return {-1 * CI->getSExtValue(), {{1, Op0}}};
if (match(V, m_NUWSub(m_Value(Op0), m_Value(Op1))))
return {0, {{1, Op0}, {-1, Op1}}};
if (match(V, m_NUWSub(m_Value(Op0), m_Value(Op1)))) {
auto ResA = decompose(Op0, Preconditions, IsSigned, DL);
auto ResB = decompose(Op1, Preconditions, IsSigned, DL);
ResA.sub(ResB);
return ResA;
}

return {V, IsKnownNonNegative};
}
Expand Down
120 changes: 117 additions & 3 deletions llvm/test/Transforms/ConstraintElimination/sub-nuw.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -319,10 +319,10 @@ define i1 @sub_nuw_neg_i16(i16 %a) {
; CHECK-NEXT: [[C_1:%.*]] = icmp ugt i16 0, [[NEG2]]
; CHECK-NEXT: br i1 [[C_1]], label [[EXIT_1:%.*]], label [[EXIT_2:%.*]]
; CHECK: exit.1:
; CHECK-NEXT: ret i1 false
; CHECK-NEXT: [[C_2:%.*]] = icmp ugt i16 [[A]], 0
; CHECK-NEXT: ret i1 [[C_2]]
; CHECK: exit.2:
; CHECK-NEXT: [[C_3:%.*]] = icmp ugt i16 [[A]], 0
; CHECK-NEXT: ret i1 [[C_3]]
; CHECK-NEXT: ret i1 true
;
entry:
%neg2 = sub nuw i16 %a, -305
Expand Down Expand Up @@ -380,3 +380,117 @@ entry:
%c = icmp ugt i64 %neg2, 0
ret i1 %c
}

define i1 @pr76713(i16 %i1, i16 %i3) {
; CHECK-LABEL: @pr76713(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[C1:%.*]] = icmp ult i16 [[I1:%.*]], -1
; CHECK-NEXT: [[C2:%.*]] = icmp uge i16 [[I1]], -3
; CHECK-NEXT: [[C3:%.*]] = icmp ult i16 [[I3:%.*]], 2
; CHECK-NEXT: [[AND:%.*]] = and i1 [[C1]], [[C2]]
; CHECK-NEXT: [[AND_2:%.*]] = and i1 [[AND]], [[C3]]
; CHECK-NEXT: br i1 [[AND]], label [[THEN:%.*]], label [[ELSE:%.*]]
; CHECK: then:
; CHECK-NEXT: [[SUB:%.*]] = sub nuw nsw i16 [[I1]], -3
; CHECK-NEXT: [[ARRAYIDX_IDX:%.*]] = mul nuw nsw i16 [[I3]], 4
; CHECK-NEXT: [[I6:%.*]] = add nuw nsw i16 [[ARRAYIDX_IDX]], [[SUB]]
; CHECK-NEXT: [[C4:%.*]] = icmp ult i16 12, [[I6]]
; CHECK-NEXT: ret i1 [[C4]]
; CHECK: else:
; CHECK-NEXT: ret i1 false
;
entry:
%c1 = icmp ult i16 %i1, -1
%c2 = icmp uge i16 %i1, -3
%c3 = icmp ult i16 %i3, 2
%and = and i1 %c1, %c2
%and.2 = and i1 %and, %c3
br i1 %and, label %then, label %else

then:
%sub = sub nuw nsw i16 %i1, -3
%arrayidx.idx = mul nuw nsw i16 %i3, 4
%i6 = add nuw nsw i16 %arrayidx.idx, %sub
%c4 = icmp ult i16 12, %i6
ret i1 %c4

else:
ret i1 0
}

define void @sub_nuw_chained_positive_constants(i16 %a) {
; CHECK-LABEL: @sub_nuw_chained_positive_constants(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SUB1:%.*]] = sub nuw i16 [[A:%.*]], 10
; CHECK-NEXT: [[SUB2:%.*]] = sub nuw i16 [[SUB1]], 20
; CHECK-NEXT: [[C_1:%.*]] = icmp ugt i16 [[SUB2]], 90
; CHECK-NEXT: br i1 [[C_1]], label [[EXIT_1:%.*]], label [[EXIT_2:%.*]]
; CHECK: exit.1:
; CHECK-NEXT: call void @use(i1 true)
; CHECK-NEXT: [[C_3:%.*]] = icmp ugt i16 [[A]], 121
; CHECK-NEXT: call void @use(i1 [[C_3]])
; CHECK-NEXT: ret void
; CHECK: exit.2:
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: ret void
;
entry:
%sub1 = sub nuw i16 %a, 10
%sub2 = sub nuw i16 %sub1, 20
%c.1 = icmp ugt i16 %sub2, 90
br i1 %c.1, label %exit.1, label %exit.2

exit.1:
%c.2 = icmp ugt i16 %a, 120
call void @use(i1 %c.2)
%c.3 = icmp ugt i16 %a, 121
call void @use(i1 %c.3)
ret void

exit.2:
%c.4 = icmp ugt i16 %a, 120
call void @use(i1 %c.4)
%c.5 = icmp ugt i16 %a, 121
call void @use(i1 %c.5)
ret void
}

define void @sub_nuw_chained_negative_constants(i8 %a) {
; CHECK-LABEL: @sub_nuw_chained_negative_constants(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SUB1:%.*]] = sub nuw i8 [[A:%.*]], 10
; CHECK-NEXT: [[SUB2:%.*]] = sub nuw i8 [[SUB1]], -126
; CHECK-NEXT: [[C_1:%.*]] = icmp ugt i8 [[SUB2]], 20
; CHECK-NEXT: br i1 [[C_1]], label [[EXIT_1:%.*]], label [[EXIT_2:%.*]]
; CHECK: exit.1:
; CHECK-NEXT: call void @use(i1 true)
; CHECK-NEXT: [[C_3:%.*]] = icmp ugt i8 [[A]], -95
; CHECK-NEXT: call void @use(i1 [[C_3]])
; CHECK-NEXT: ret void
; CHECK: exit.2:
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: ret void
;
entry:
%sub1 = sub nuw i8 %a, 10
%sub2 = sub nuw i8 %sub1, 130
%c.1 = icmp ugt i8 %sub2, 20
br i1 %c.1, label %exit.1, label %exit.2

exit.1:
%c.2 = icmp ugt i8 %a, 160
call void @use(i1 %c.2)
%c.3 = icmp ugt i8 %a, 161
call void @use(i1 %c.3)
ret void


exit.2:
%c.4 = icmp ugt i8 %a, 160
call void @use(i1 %c.4)
%c.5 = icmp ugt i8 %a, 161
call void @use(i1 %c.5)
ret void
}