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clang-p2996/clang/test/CodeGen/tbaa-pointers.c
Florian Hahn 77d3f8a925 [TBAA] Don't emit pointer-tbaa for void pointers. (#122116) 
While there are no special rules in the standards regarding void
pointers and strict aliasing, emitting distinct tags for void pointers
break some common idioms and there is no good alternative to re-write
the code without strict-aliasing violations. An example is to count the
entries in an array of pointers:

    int count_elements(void * values) {
      void **seq = values;
      int count;
      for (count = 0; seq && seq[count]; count++);
      return count;
    }

https://clang.godbolt.org/z/8dTv51v8W

An example in the wild is from
https://github.com/llvm/llvm-project/issues/119099

This patch avoids emitting distinct tags for void pointers, to avoid
those idioms causing mis-compiles for now.

Fixes https://github.com/llvm/llvm-project/issues/119099.
Fixes https://github.com/llvm/llvm-project/issues/122537.

PR: https://github.com/llvm/llvm-project/pull/122116
2025-01-31 11:38:14 +00:00

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// RUN: %clang_cc1 -triple x86_64-apple-darwin -O1 -disable-llvm-passes -no-pointer-tbaa %s -emit-llvm -o - | FileCheck --check-prefixes=COMMON,DISABLE %s
// RUN: %clang_cc1 -triple x86_64-apple-darwin -O1 -disable-llvm-passes %s -emit-llvm -o - | FileCheck --check-prefixes=COMMON,DEFAULT %s
// RUN: %clang --target=x86_64-apple-darwin -O1 -fno-pointer-tbaa %s -emit-llvm -S -mllvm -disable-llvm-optzns -o - | FileCheck --check-prefixes=COMMON,DISABLE %s
// RUN: %clang --target=x86_64-apple-darwin -O1 %s -emit-llvm -S -mllvm -disable-llvm-optzns -o - | FileCheck --check-prefixes=COMMON,DEFAULT %s
void p2unsigned(unsigned **ptr) {
// COMMON-LABEL: define void @p2unsigned(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P2INT_0:!.+]]
// DEFAULT-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P2INT_0]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE]], align 8, !tbaa [[P1INT_0:!.+]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR:!.+]]
// DISABLE-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: store ptr null, ptr [[BASE]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
*ptr = 0;
}
void p2unsigned_volatile(unsigned *volatile *ptr) {
// COMMON-LABEL: define void @p2unsigned_volatile(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P2INT_0]]
// DEFAULT-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P2INT_0]]
// DEFAULT-NEXT: store volatile ptr null, ptr [[BASE]], align 8, !tbaa [[P1INT_0]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: store volatile ptr null, ptr [[BASE]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
*ptr = 0;
}
void p3int(int ***ptr) {
// COMMON-LABEL: define void @p3int(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P3INT_0:!.+]]
// DEFAULT-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P3INT_0]]
// DEFAULT-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[P2INT_0]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE_1]], align 8, !tbaa [[P1INT_0]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: store ptr null, ptr [[BASE_1]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
**ptr = 0;
}
void p4char(char ****ptr) {
// COMMON-LABEL: define void @p4char(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P4CHAR_0:!.+]]
// DEFAULT-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P4CHAR_0]]
// DEFAULT-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[P3CHAR_0:!.+]]
// DEFAULT-NEXT: [[BASE_2:%.+]] = load ptr, ptr [[BASE_1]], align 8, !tbaa [[P2CHAR_0:!.+]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE_2]], align 8, !tbaa [[P1CHAR_0:!.+]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_2:%.+]] = load ptr, ptr [[BASE_1]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: store ptr null, ptr [[BASE_2]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
***ptr = 0;
}
void p4char_const1(const char ****ptr) {
// COMMON-LABEL: define void @p4char_const1(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P4CHAR_0]]
// DEFAULT-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P4CHAR_0]]
// DEFAULT-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[P3CHAR_0]]
// DEFAULT-NEXT: [[BASE_2:%.+]] = load ptr, ptr [[BASE_1]], align 8, !tbaa [[P2CHAR_0]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE_2]], align 8, !tbaa [[P1CHAR_0]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_2:%.+]] = load ptr, ptr [[BASE_1]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: store ptr null, ptr [[BASE_2]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
***ptr = 0;
}
void p4char_const2(const char **const **ptr) {
// COMMON-LABEL: define void @p4char_const2(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P4CHAR_0]]
// DEFAULT-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P4CHAR_0]]
// DEFAULT-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[P3CHAR_0]]
// DEFAULT-NEXT: [[BASE_2:%.+]] = load ptr, ptr [[BASE_1]], align 8, !tbaa [[P2CHAR_0]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE_2]], align 8, !tbaa [[P1CHAR_0]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_1:%.+]] = load ptr, ptr [[BASE_0]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE_2:%.+]] = load ptr, ptr [[BASE_1]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: store ptr null, ptr [[BASE_2]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
***ptr = 0;
}
struct S1 {
int x;
int y;
};
void p2struct(struct S1 **ptr) {
// COMMON-LABEL: define void @p2struct(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P2S1_TAG:!.+]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DEFAULT-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P2S1_TAG]]
// DISABLE-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE]], align 8, !tbaa [[P1S1_TAG:!.+]]
// DISABLE-NEXT: store ptr null, ptr [[BASE]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
*ptr = 0;
}
void p2struct_const(struct S1 const **ptr) {
// COMMON-LABEL: define void @p2struct_const(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// COMMON-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR:!.+]]
// COMMON-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DEFAULT-NEXT: store ptr null, ptr [[BASE]], align 8, !tbaa [[P1S1_TAG]]
// DISABLE-NEXT: store ptr null, ptr [[BASE]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: ret void
//
*ptr = 0;
}
struct S2 {
struct S1 *s;
};
void p2struct2(struct S2 *ptr) {
// COMMON-LABEL: define void @p2struct2(
// COMMON-SAME: ptr noundef [[PTR:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P1S2_TAG:!.+]]
// DEFAULT-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P1S2_TAG]]
// DEFAULT-NEXT: [[S:%.+]] = getelementptr inbounds nuw %struct.S2, ptr [[BASE]], i32 0, i32 0
// DEFAULT-NEXT: store ptr null, ptr [[S]], align 8, !tbaa [[S2_S_TAG:!.+]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[BASE:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DISABLE-NEXT: [[S:%.+]] = getelementptr inbounds nuw %struct.S2, ptr [[BASE]], i32 0, i32 0
// DISABLE-NEXT: store ptr null, ptr [[S]], align 8, !tbaa [[S2_S_TAG:!.+]]
// COMMON-NEXT: ret void
ptr->s = 0;
}
void vla1(int n, int ptr[][n], int idx) {
// COMMON-LABEL: define void @vla1(
// COMMON-SAME: i32 noundef [[N:%.+]], ptr noundef [[PTR:%.+]], i32 noundef [[IDX:%.+]])
// COMMON: [[N_ADDR:%.+]] = alloca i32, align 4
// COMMON-NEXT: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// COMMON-NEXT: [[IDX_ADDR:%.+]] = alloca i32, align 4
// COMMON-NEXT: store i32 [[N]], ptr [[N_ADDR]], align 4, !tbaa [[INT_TY:!.+]]
// DEFAULT-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[P1INT0:!.+]]
// DISABLE-NEXT: store ptr [[PTR]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: store i32 [[IDX]], ptr [[IDX_ADDR]], align 4, !tbaa [[INT_TY]]
// COMMON-NEXT: [[L:%.+]] = load i32, ptr [[N_ADDR]], align 4, !tbaa [[INT_TY]]
// COMMON-NEXT: [[L_EXT:%.+]] = zext i32 [[L]] to i64
// DEFAULT-NEXT: [[L_PTR:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[P1INT0]]
// DISABLE-NEXT: [[L_PTR:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: [[L_IDX:%.+]] = load i32, ptr [[IDX_ADDR]], align 4, !tbaa [[INT_TY]]
// COMMON-NEXT: [[IDX_EXT:%.+]] = sext i32 [[L_IDX]] to i64
// COMMON-NEXT: [[MUL:%.+]] = mul nsw i64 [[IDX_EXT]], [[L_EXT]]
// COMMON-NEXT: [[GEP1:%.+]] = getelementptr inbounds i32, ptr [[L_PTR]], i64 [[MUL]]
// COMMON-NEXT: [[GEP2:%.+]] = getelementptr inbounds i32, ptr [[GEP1]], i64 0
// COMMON-NEXT: store i32 0, ptr [[GEP2]], align 4, !tbaa [[INT_TAG:!.+]]
// DEFAULT-NEXT: ret void
ptr[idx][0] = 0;
}
typedef struct {
int i1;
} TypedefS;
void unamed_struct_typedef(TypedefS *ptr) {
// COMMON-LABEL: define void @unamed_struct_typedef(
// COMMON-SAME: ptr noundef [[PTRA:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// DISABLE-NEXT: store ptr [[PTRA]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// DEFAULT-NEXT: store ptr [[PTRA]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR:!.+]]
// COMMON-NEXT: [[L0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: [[GEP:%.+]] = getelementptr inbounds nuw %struct.TypedefS, ptr [[L0]], i32 0, i32 0
// COMMON-NEXT: store i32 0, ptr [[GEP]], align 4
// COMMON-NEXT: ret void
ptr->i1 = 0;
}
int void_ptrs(void **ptr) {
// COMMON-LABEL: define i32 @void_ptrs(
// COMMON-SAME: ptr noundef [[PTRA:%.+]])
// COMMON: [[PTR_ADDR:%.+]] = alloca ptr, align 8
// COMMON-NEXT: store ptr [[PTRA]], ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: [[L0:%.+]] = load ptr, ptr [[PTR_ADDR]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: [[L1:%.+]] = load ptr, ptr [[L0]], align 8, !tbaa [[ANYPTR]]
// COMMON-NEXT: [[BOOL:%.+]] = icmp ne ptr [[L1]], null
// COMMON-NEXT: [[BOOL_EXT:%.+]] = zext i1 [[BOOL]] to i64
// COMMON-NEXT: [[COND:%.+]] = select i1 [[BOOL]], i32 0, i32 1
// COMMON-NEXT: ret i32 [[COND]]
return *ptr ? 0 : 1;
}
// DEFAULT: [[P2INT_0]] = !{[[P2INT:!.+]], [[P2INT]], i64 0}
// DEFAULT: [[P2INT]] = !{!"p2 int", [[ANY_POINTER:!.+]], i64 0}
// DISABLE: [[ANYPTR]] = !{[[ANY_POINTER:!.+]], [[ANY_POINTER]], i64 0}
// COMMON: [[ANY_POINTER]] = !{!"any pointer", [[CHAR:!.+]], i64 0}
// COMMON: [[CHAR]] = !{!"omnipotent char", [[TBAA_ROOT:!.+]], i64 0}
// COMMON: [[TBAA_ROOT]] = !{!"Simple C/C++ TBAA"}
// DEFAULT: [[P1INT_0]] = !{[[P1INT:!.+]], [[P1INT]], i64 0}
// DEFAULT: [[P1INT]] = !{!"p1 int", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P3INT_0]] = !{[[P3INT:!.+]], [[P3INT]], i64 0}
// DEFAULT: [[P3INT]] = !{!"p3 int", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P4CHAR_0]] = !{[[P4CHAR:!.+]], [[P4CHAR]], i64 0}
// DEFAULT: [[P4CHAR]] = !{!"p4 omnipotent char", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P3CHAR_0]] = !{[[P3CHAR:!.+]], [[P3CHAR]], i64 0}
// DEFAULT: [[P3CHAR]] = !{!"p3 omnipotent char", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P2CHAR_0]] = !{[[P2CHAR:!.+]], [[P2CHAR]], i64 0}
// DEFAULT: [[P2CHAR]] = !{!"p2 omnipotent char", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P1CHAR_0]] = !{[[P1CHAR:!.+]], [[P1CHAR]], i64 0}
// DEFAULT: [[P1CHAR]] = !{!"p1 omnipotent char", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P2S1_TAG]] = !{[[P2S1:!.+]], [[P2S1]], i64 0}
// DEFAULT: [[P2S1]] = !{!"p2 _ZTS2S1", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P1S1_TAG:!.+]] = !{[[P1S1:!.+]], [[P1S1]], i64 0}
// DEFAULT: [[P1S1]] = !{!"p1 _ZTS2S1", [[ANY_POINTER]], i64 0}
// DEFAULT: [[P1S2_TAG]] = !{[[P1S2:!.+]], [[P1S2]], i64 0}
// DEFAULT: [[P1S2]] = !{!"p1 _ZTS2S2", [[ANY_POINTER]], i64 0}
// DEFAULT: [[S2_S_TAG]] = !{[[S2_TY:!.+]], [[P1S1]], i64 0}
// DEFAULT: [[S2_TY]] = !{!"S2", [[P1S1]], i64 0}
// DISABLE: [[S2_S_TAG]] = !{[[S2_TY:!.+]], [[ANY_POINTER]], i64 0}
// DISABLE: [[S2_TY]] = !{!"S2", [[ANY_POINTER]], i64 0}
// COMMON: [[INT_TAG]] = !{[[INT_TY:!.+]], [[INT_TY]], i64 0}
// COMMON: [[INT_TY]] = !{!"int", [[CHAR]], i64 0}
// DEFAULT: [[ANYPTR]] = !{[[ANY_POINTER]], [[ANY_POINTER]], i64 0}
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