Skip to content

[InstSimplify] Support non-inbounds GEP in ptrdiff fold #162676

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
merged 2 commits into from
Oct 10, 2025
+4 −8
Merged

[InstSimplify] Support non-inbounds GEP in ptrdiff fold #162676

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
dde327d
[InstSimplify] Support non-inbounds GEP in ptrdiff fold
nikic Oct 9, 2025
dadb801
Merge branch 'main' into instsimplify-ptrdiff-no-inbounds
nikic Oct 10, 2025
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
6 changes: 3 additions & 3 deletions llvm/lib/Analysis/InstructionSimplify.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -671,12 +671,12 @@ Value *llvm::simplifyAddInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
/// This is very similar to stripAndAccumulateConstantOffsets(), except it
/// normalizes the offset bitwidth to the stripped pointer type, not the
/// original pointer type.
static APInt stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V,
bool AllowNonInbounds = false) {
static APInt stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V) {
assert(V->getType()->isPtrOrPtrVectorTy());

APInt Offset = APInt::getZero(DL.getIndexTypeSizeInBits(V->getType()));
V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds);
V = V->stripAndAccumulateConstantOffsets(DL, Offset,
/*AllowNonInbounds=*/true);
// As that strip may trace through `addrspacecast`, need to sext or trunc
// the offset calculated.
return Offset.sextOrTrunc(DL.getIndexTypeSizeInBits(V->getType()));
Expand Down
6 changes: 1 addition & 5 deletions llvm/test/Transforms/InstSimplify/ptr_diff.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,11 +14,7 @@ define i64 @ptrdiff(ptr %ptr) {

define i64 @ptrdiff_no_inbounds(ptr %ptr) {
; CHECK-LABEL: @ptrdiff_no_inbounds(
; CHECK-NEXT: [[LAST:%.*]] = getelementptr i8, ptr [[PTR:%.*]], i32 42
; CHECK-NEXT: [[FIRST_INT:%.*]] = ptrtoint ptr [[PTR]] to i64
; CHECK-NEXT: [[LAST_INT:%.*]] = ptrtoint ptr [[LAST]] to i64
; CHECK-NEXT: [[DIFF:%.*]] = sub i64 [[LAST_INT]], [[FIRST_INT]]
; CHECK-NEXT: ret i64 [[DIFF]]
; CHECK-NEXT: ret i64 42
;
%last = getelementptr i8, ptr %ptr, i32 42
%first.int = ptrtoint ptr %ptr to i64
Expand Down
Loading