e18c6ef6b4
"Listing the alignment and access size (== expected alignment) in the warning
seems like a good idea."
solves PR 46947
struct Foo {
struct Bar {
void * a;
void * b;
};
Bar bar;
};
struct ThirtyTwo {
struct Large {
void * a;
void * b;
void * c;
void * d;
};
Large bar;
};
void braz(Foo *foo, ThirtyTwo *braz) {
Foo::Bar bar;
__atomic_load(&foo->bar, &bar, __ATOMIC_RELAXED);
ThirtyTwo::Large foobar;
__atomic_load(&braz->bar, &foobar, __ATOMIC_RELAXED);
}
repro.cpp:21:3: warning: misaligned atomic operation may incur significant performance penalty; the expected (16 bytes) exceeds the actual alignment (8 bytes) [-Watomic-alignment]
__atomic_load(&foo->bar, &bar, __ATOMIC_RELAXED);
^
repro.cpp:24:3: warning: misaligned atomic operation may incur significant performance penalty; the expected (32 bytes) exceeds the actual alignment (8 bytes) [-Watomic-alignment]
__atomic_load(&braz->bar, &foobar, __ATOMIC_RELAXED);
^
repro.cpp:24:3: warning: large atomic operation may incur significant performance penalty; the access size (32 bytes) exceeds the max lock-free size (16 bytes) [-Watomic-alignment]
3 warnings generated.
Differential Revision: https://reviews.llvm.org/D85102
49 lines
2.0 KiB
C
49 lines
2.0 KiB
C
// RUN: %clang_cc1 -triple aarch64-linux-gnu %s -emit-llvm -o /dev/null -verify
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typedef struct {
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int a, b;
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} IntPair;
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typedef struct {
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long long a;
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} LongStruct;
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typedef int __attribute__((aligned(1))) unaligned_int;
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void func(IntPair *p) {
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IntPair res;
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__atomic_load(p, &res, 0); // expected-warning {{misaligned atomic operation may incur significant performance penalty; the expected alignment (8 bytes) exceeds the actual alignment (4 bytes)}}
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__atomic_store(p, &res, 0); // expected-warning {{misaligned atomic operation may incur significant performance penalty; the expected alignment (8 bytes) exceeds the actual alignment (4 bytes)}}
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__atomic_fetch_add((unaligned_int *)p, 1, 2); // expected-warning {{misaligned atomic operation may incur significant performance penalty; the expected alignment (4 bytes) exceeds the actual alignment (1 bytes)}}
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__atomic_fetch_sub((unaligned_int *)p, 1, 3); // expected-warning {{misaligned atomic operation may incur significant performance penalty; the expected alignment (4 bytes) exceeds the actual alignment (1 bytes)}}
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}
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void func1(LongStruct *p) {
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LongStruct res;
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__atomic_load(p, &res, 0);
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__atomic_store(p, &res, 0);
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__atomic_fetch_add((int *)p, 1, 2);
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__atomic_fetch_sub((int *)p, 1, 3);
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}
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typedef struct {
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void *a;
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void *b;
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} Foo;
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typedef struct {
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void *a;
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void *b;
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void *c;
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void *d;
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} __attribute__((aligned(32))) ThirtyTwo;
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void braz(Foo *foo, ThirtyTwo *braz) {
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Foo bar;
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__atomic_load(foo, &bar, __ATOMIC_RELAXED); // expected-warning {{misaligned atomic operation may incur significant performance penalty; the expected alignment (16 bytes) exceeds the actual alignment (8 bytes)}}
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ThirtyTwo thirtyTwo1;
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ThirtyTwo thirtyTwo2;
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__atomic_load(&thirtyTwo1, &thirtyTwo2, __ATOMIC_RELAXED); // expected-warning {{large atomic operation may incur significant performance penalty; the access size (32 bytes) exceeds the max lock-free size (16 bytes)}}
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}
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