Skip to content

[InstCombine] Improve foldAndOrOfICmpsUsingRanges #67327

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
+42 −19
Closed

[InstCombine] Improve foldAndOrOfICmpsUsingRanges #67327

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
54 changes: 40 additions & 14 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1273,23 +1273,46 @@ Value *InstCombinerImpl::foldAndOrOfICmpsUsingRanges(ICmpInst *ICmp1,
ICmpInst::Predicate Pred1, Pred2;
Value *V1, *V2;
const APInt *C1, *C2;
if (!match(ICmp1, m_ICmp(Pred1, m_Value(V1), m_APInt(C1))) ||
!match(ICmp2, m_ICmp(Pred2, m_Value(V2), m_APInt(C2))))
return nullptr;

// Look through add of a constant offset on V1, V2, or both operands. This
// allows us to interpret the V + C' < C'' range idiom into a proper range.
const APInt *Offset1 = nullptr, *Offset2 = nullptr;
if (V1 != V2) {
Value *X;
if (match(V1, m_Add(m_Value(X), m_APInt(Offset1))))
V1 = X;
if (match(V2, m_Add(m_Value(X), m_APInt(Offset2))))
V2 = X;
bool Matched = false;

if (match(ICmp1, m_ICmp(Pred1, m_Value(V1), m_APInt(C1))) &&
match(ICmp2, m_ICmp(Pred2, m_Value(V2), m_APInt(C2)))) {
// Look through add of a constant offset on V1, V2, or both operands. This
// allows us to interpret the V + C' < C'' range idiom into a proper range.
if (V1 != V2) {
Value *X;
if (match(V1, m_Add(m_Value(X), m_APInt(Offset1))))
V1 = X;
if (match(V2, m_Add(m_Value(X), m_APInt(Offset2))))
V2 = X;
}

Matched = V1 == V2;
}

if (V1 != V2)
if (!Matched) {
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr;
// Match (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
auto MaskPair =
getMaskedTypeForICmpPair(A, B, C, D, E, ICmp1, ICmp2, Pred1, Pred2);
// Match (icmp(A & B) ==/!= C1) &/| (icmp(A & B) ==/!= C2)
if (MaskPair && B == D && match(C, m_APIntAllowUndef(C1)) &&
match(E, m_APIntAllowUndef(C2)) &&
(match(ICmp1->getOperand(0),
m_CombineAnd(m_Value(V1),
m_c_And(m_Specific(A), m_Specific(B)))) ||
match(ICmp2->getOperand(0),
m_CombineAnd(m_Value(V1),
m_c_And(m_Specific(A), m_Specific(D)))))) {
V2 = V1;
Matched = true;
}
}

if (!Matched)
return nullptr;
assert(V1 == V2);
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

nit: assert msg


ConstantRange CR1 = ConstantRange::makeExactICmpRegion(
IsAnd ? ICmpInst::getInversePredicate(Pred1) : Pred1, *C1);
Expand Down Expand Up @@ -3183,6 +3206,9 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
Constant::getAllOnesValue(LHS0->getType()));
}

if (Value *V = foldAndOrOfICmpsUsingRanges(LHS, RHS, IsAnd))
return V;

// This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
if (!LHSC || !RHSC)
return nullptr;
Expand Down Expand Up @@ -3256,7 +3282,7 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
}
}

return foldAndOrOfICmpsUsingRanges(LHS, RHS, IsAnd);
return nullptr;
}

// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
Expand Down
7 changes: 2 additions & 5 deletions llvm/test/Transforms/InstCombine/icmp-range.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1480,11 +1480,8 @@ define <2 x i1> @icmp_ne_sext_eq_otherwise_vec(<2 x i32> %a) {
; tests from PR59555
define i1 @isFloat(i64 %0) {
; CHECK-LABEL: @isFloat(
; CHECK-NEXT: [[TMP2:%.*]] = icmp ugt i64 [[TMP0:%.*]], 281474976710655
; CHECK-NEXT: [[TMP3:%.*]] = and i64 [[TMP0]], -281474976710656
; CHECK-NEXT: [[TMP4:%.*]] = icmp ne i64 [[TMP3]], 281474976710656
; CHECK-NEXT: [[TMP5:%.*]] = and i1 [[TMP2]], [[TMP4]]
; CHECK-NEXT: ret i1 [[TMP5]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp ugt i64 [[TMP0:%.*]], 562949953421311
; CHECK-NEXT: ret i1 [[TMP2]]
;
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

  1. please add more robust tests. Think you need some negative ones. Maybe:
  • B != D
  • some of the explicit pattern (with both sides eq/ne)
  • some non eq/ne patterns with a pred that can't be matched in mask pattern (maybe some signed preds, non-mask + ugt, etc...)
  • some vec tests with undef elements.

%2 = icmp ugt i64 %0, 281474976710655
%3 = and i64 %0, -281474976710656
Expand Down