Author: Aaron Ballman Date: 2025-05-27T14:59:30-04:00 New Revision: d1a6327b2b5d859c992599ac217aaa6d8b83a998
URL: https://github.com/llvm/llvm-project/commit/d1a6327b2b5d859c992599ac217aaa6d8b83a998 DIFF: https://github.com/llvm/llvm-project/commit/d1a6327b2b5d859c992599ac217aaa6d8b83a998.diff LOG: [C2y] Fix _Countof handling of VLAs (#141621) It turns out that getVLASize() does not get you the size of a single dimension of the VLA, it gets you the full count of all elements. This caused _Countof to return invalid values on VLA ranks. Now switched to using getVLAElements1D() instead, which only gets a single dimension. Fixes #141409 Added: Modified: clang/lib/CodeGen/CGExprScalar.cpp clang/test/C/C2y/n3369_3.c Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp index b9eb12efd6670..111b5805c6a94 100644 --- a/clang/lib/CodeGen/CGExprScalar.cpp +++ b/clang/lib/CodeGen/CGExprScalar.cpp @@ -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) { diff --git a/clang/test/C/C2y/n3369_3.c b/clang/test/C/C2y/n3369_3.c index d3909b2e5bc92..792c076413372 100644 --- a/clang/test/C/C2y/n3369_3.c +++ b/clang/test/C/C2y/n3369_3.c @@ -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; +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
