0dd05d4b59
Richard noted in the review of r217349 that extra handling of
__builtin_assume_aligned inside of the expression evaluator was needed. He was
right, and this should address the concerns raised, namely:
1. The offset argument to __builtin_assume_aligned can have side effects, and
we need to make sure that all arguments are properly evaluated.
2. If the alignment assumption does not hold, that introduces undefined
behavior, and undefined behavior cannot appear inside a constexpr.
and hopefully the diagnostics produced are detailed enough to explain what is
going on.
llvm-svn: 218992
50 lines
2.8 KiB
C++
50 lines
2.8 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -triple x86_64-linux-gnu %s
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int n;
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constexpr int *p = 0;
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// expected-error@+1 {{must be initialized by a constant expression}}
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constexpr int *k = (int *) __builtin_assume_aligned(p, 16, n = 5);
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constexpr void *l = __builtin_assume_aligned(p, 16);
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{cast from 'void *' is not allowed in a constant expression}}
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constexpr int *c = (int *) __builtin_assume_aligned(p, 16);
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{alignment of the base pointee object (4 bytes) is less than the asserted 16 bytes}}
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constexpr void *m = __builtin_assume_aligned(&n, 16);
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{offset of the aligned pointer from the base pointee object (-2 bytes) is not a multiple of the asserted 4 bytes}}
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constexpr void *q1 = __builtin_assume_aligned(&n, 4, 2);
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{offset of the aligned pointer from the base pointee object (2 bytes) is not a multiple of the asserted 4 bytes}}
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constexpr void *q2 = __builtin_assume_aligned(&n, 4, -2);
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constexpr void *q3 = __builtin_assume_aligned(&n, 4, 4);
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constexpr void *q4 = __builtin_assume_aligned(&n, 4, -4);
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static char ar1[6];
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{alignment of the base pointee object (1 byte) is less than the asserted 16 bytes}}
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constexpr void *r1 = __builtin_assume_aligned(&ar1[2], 16);
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static char ar2[6] __attribute__((aligned(32)));
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{offset of the aligned pointer from the base pointee object (2 bytes) is not a multiple of the asserted 16 bytes}}
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constexpr void *r2 = __builtin_assume_aligned(&ar2[2], 16);
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constexpr void *r3 = __builtin_assume_aligned(&ar2[2], 16, 2);
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{offset of the aligned pointer from the base pointee object (1 byte) is not a multiple of the asserted 16 bytes}}
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constexpr void *r4 = __builtin_assume_aligned(&ar2[2], 16, 1);
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constexpr int* x = __builtin_constant_p((int*)0xFF) ? (int*)0xFF : (int*)0xFF;
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{value of the aligned pointer (255) is not a multiple of the asserted 32 bytes}}
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constexpr void *s1 = __builtin_assume_aligned(x, 32);
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// expected-error@+2 {{must be initialized by a constant expression}}
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// expected-note@+1 {{value of the aligned pointer (250) is not a multiple of the asserted 32 bytes}}
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constexpr void *s2 = __builtin_assume_aligned(x, 32, 5);
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constexpr void *s3 = __builtin_assume_aligned(x, 32, -1);
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