Skip to content

[ValueTracking] Infer X u<= X +nuw Y for any Y #75524

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

Merged
dtcxzyw merged 3 commits into from
Dec 15, 2023
Merged

[ValueTracking] Infer X u<= X +nuw Y for any Y #75524

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
41b120e
[ValueTracking] Add pre-commit tests from PR70374. NFC.
dtcxzyw Dec 14, 2023
c29fa5a
[ValueTracking] Infer `X u<= X +nuw Y` for any Y
dtcxzyw Dec 14, 2023
310fdf2
[ValueTracking] Add a commuted add test. NFC.
dtcxzyw Dec 15, 2023
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
7 changes: 3 additions & 4 deletions llvm/lib/Analysis/ValueTracking.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8102,10 +8102,9 @@ static bool isTruePredicate(CmpInst::Predicate Pred, const Value *LHS,
}

case CmpInst::ICMP_ULE: {
const APInt *C;

// LHS u<= LHS +_{nuw} C for any C
if (match(RHS, m_NUWAdd(m_Specific(LHS), m_APInt(C))))
// LHS u<= LHS +_{nuw} V for any V
if (match(RHS, m_c_Add(m_Specific(LHS), m_Value())) &&
cast<OverflowingBinaryOperator>(RHS)->hasNoUnsignedWrap())
return true;

// RHS >> V u<= RHS for any V
Expand Down
38 changes: 38 additions & 0 deletions llvm/test/Transforms/InstSimplify/implies.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -316,6 +316,44 @@ define i1 @test_uge_icmp(i32 %length.i, i32 %i) {
ret i1 %res
}

; Test from PR70374
define i1 @pr70374(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @pr70374(
; CHECK-NEXT: [[ADD:%.*]] = add nuw i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[CMP1:%.*]] = icmp ule i32 [[ADD]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[CMP1]]
;
%add = add nuw i32 %y, %z
%cmp1 = icmp ule i32 %add, %x
%cmp2 = icmp uge i32 %x, %y
%res = and i1 %cmp2, %cmp1
ret i1 %res
}

define i1 @pr70374_commuted_add(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @pr70374_commuted_add(
; CHECK-NEXT: [[ADD:%.*]] = add nuw i32 [[Z:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP1:%.*]] = icmp ule i32 [[ADD]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[CMP1]]
;
%add = add nuw i32 %z, %y
%cmp1 = icmp ule i32 %add, %x
%cmp2 = icmp uge i32 %x, %y
%res = and i1 %cmp2, %cmp1
ret i1 %res
}

define i1 @test_uge_icmp_value(i32 %length.i, i32 %i, i32 %j) {
; CHECK-LABEL: @test_uge_icmp_value(
; CHECK-NEXT: ret i1 true
;
%iplusj = add nuw i32 %i, %j
%var29 = icmp uge i32 %length.i, %i
%var30 = icmp uge i32 %length.i, %iplusj
%res = icmp ule i1 %var30, %var29
ret i1 %res
}

; negative case, X + 1 <(s) Y !==> X <(s) Y (X = 0x7fffffff, Y = 0x7fbfffff)
define i1 @test_sgt_icmp_no_nsw(i32 %length.i, i32 %i) {
; CHECK-LABEL: @test_sgt_icmp_no_nsw(
Expand Down