Skip to content

[C2y] Fix _Countof handling of VLAs #141621

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
May 27, 2025
Merged

[C2y] Fix _Countof handling of VLAs #141621

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
b7736e6
[C2y] Fix _Countof handling of VLAs
AaronBallman May 27, 2025
3d65e3e
Refactor to use an early return
AaronBallman May 27, 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
22 changes: 11 additions & 11 deletions clang/lib/CodeGen/CGExprScalar.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3574,20 +3574,20 @@ ScalarExprEmitter::VisitUnaryExprOrTypeTraitExpr(
CGF.EmitIgnoredExpr(E->getArgumentExpr());
}

auto VlaSize = CGF.getVLASize(VAT);
llvm::Value *size = VlaSize.NumElts;
// For _Countof, we just want to return the size of a single dimension.
if (Kind == UETT_CountOf)
return CGF.getVLAElements1D(VAT).NumElts;

// For sizeof and __datasizeof, we need to scale the number of elements
// by the size of the array element type. For _Countof, we just want to
// return the size directly.
if (Kind != UETT_CountOf) {
// Scale the number of non-VLA elements by the non-VLA element size.
CharUnits eltSize = CGF.getContext().getTypeSizeInChars(VlaSize.Type);
if (!eltSize.isOne())
size = CGF.Builder.CreateNUWMul(CGF.CGM.getSize(eltSize), size);
}
// by the size of the array element type.
auto VlaSize = CGF.getVLASize(VAT);

return size;
// Scale the number of non-VLA elements by the non-VLA element size.
CharUnits eltSize = CGF.getContext().getTypeSizeInChars(VlaSize.Type);
if (!eltSize.isOne())
return CGF.Builder.CreateNUWMul(CGF.CGM.getSize(eltSize),
VlaSize.NumElts);
return VlaSize.NumElts;
}
}
} else if (E->getKind() == UETT_OpenMPRequiredSimdAlign) {
Expand Down
54 changes: 54 additions & 0 deletions clang/test/C/C2y/n3369_3.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -164,3 +164,57 @@ void test4(int n) {
int y = _Countof(int[n++][7]);
}

// CHECK-64-LABEL: define dso_local void @test5(
// CHECK-64-SAME: ) #[[ATTR0]] {
// CHECK-64-NEXT: [[ENTRY:.*:]]
// CHECK-64-NEXT: [[J:%.*]] = alloca i32, align
// CHECK-64-NEXT: [[SAVED_STACK:%.*]] = alloca ptr, align
// CHECK-64-NEXT: [[A:%.*]] = alloca i32, align
// CHECK-64-NEXT: [[B:%.*]] = alloca i32, align
// CHECK-64-NEXT: [[C:%.*]] = alloca i32, align
// CHECK-64-NEXT: [[D:%.*]] = alloca i32, align
// CHECK-64-NEXT: store i32 2, ptr [[J]], align
// CHECK-64-NEXT: [[TMP0:%.*]] = call ptr @llvm.stacksave.p0()
// CHECK-64-NEXT: store ptr [[TMP0]], ptr [[SAVED_STACK]], align
// CHECK-64-NEXT: [[VLA:%.*]] = alloca i32, i64 120, align
// CHECK-64-NEXT: store i32 1, ptr [[A]], align
// CHECK-64-NEXT: store i32 4, ptr [[B]], align
// CHECK-64-NEXT: store i32 5, ptr [[C]], align
// CHECK-64-NEXT: store i32 6, ptr [[D]], align
// CHECK-64-NEXT: [[TMP1:%.*]] = load ptr, ptr [[SAVED_STACK]], align
// CHECK-64-NEXT: call void @llvm.stackrestore.p0(ptr [[TMP1]])
// CHECK-64-NEXT: ret void
//
// CHECK-32-LABEL: define dso_local void @test5(
// CHECK-32-SAME: ) #[[ATTR0]] {
// CHECK-32-NEXT: [[ENTRY:.*:]]
// CHECK-32-NEXT: [[J:%.*]] = alloca i32, align
// CHECK-32-NEXT: [[SAVED_STACK:%.*]] = alloca ptr, align
// CHECK-32-NEXT: [[A:%.*]] = alloca i32, align
// CHECK-32-NEXT: [[B:%.*]] = alloca i32, align
// CHECK-32-NEXT: [[C:%.*]] = alloca i32, align
// CHECK-32-NEXT: [[D:%.*]] = alloca i32, align
// CHECK-32-NEXT: store i32 2, ptr [[J]], align
// CHECK-32-NEXT: [[TMP0:%.*]] = call ptr @llvm.stacksave.p0()
// CHECK-32-NEXT: store ptr [[TMP0]], ptr [[SAVED_STACK]], align
// CHECK-32-NEXT: [[VLA:%.*]] = alloca i32, i32 120, align
// CHECK-32-NEXT: store i32 1, ptr [[A]], align
// CHECK-32-NEXT: store i32 4, ptr [[B]], align
// CHECK-32-NEXT: store i32 5, ptr [[C]], align
// CHECK-32-NEXT: store i32 6, ptr [[D]], align
// CHECK-32-NEXT: [[TMP1:%.*]] = load ptr, ptr [[SAVED_STACK]], align
// CHECK-32-NEXT: call void @llvm.stackrestore.p0(ptr [[TMP1]])
// CHECK-32-NEXT: ret void
//
void test5() {
// Ensure we're getting the variable-length dimensions correctly. We were
// previously returning the size of all VLA dimensions multiplied together
// to get the total element count rather than the element count for a single
// array rank. See GH141409
const int j = 2;
int arr[1][j + 2][j + 3][j + 4];
int a = _Countof arr;
int b = _Countof *arr;
int c = _Countof **arr;
int d = _Countof ***arr;
}
Loading