564d85e090
In LLVM IR, `AlignmentBitfieldElementT` is 5-bit wide But that means that the maximal alignment exponent is `(1<<5)-2`, which is `30`, not `29`. And indeed, alignment of `1073741824` roundtrips IR serialization-deserialization. While this doesn't seem all that important, this doubles the maximal supported alignment from 512MiB to 1GiB, and there's actually one noticeable use-case for that; On X86, the huge pages can have sizes of 2MiB and 1GiB (!). So while this doesn't add support for truly huge alignments, which i think we can easily-ish do if wanted, i think this adds zero-cost support for a not-trivially-dismissable case. I don't believe we need any upgrade infrastructure, and since we don't explicitly record the IR version, we don't need to bump one either. As @craig.topper speculates in D108661#2963519, this might be an artificial limit imposed by the original implementation of the `getAlignment()` functions. Differential Revision: https://reviews.llvm.org/D108661
32 lines
1.9 KiB
C
32 lines
1.9 KiB
C
// RUN: %clang_cc1 -fsyntax-only -verify %s
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// return values
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void test_void_alloc_align(void) __attribute__((alloc_align(1))); // expected-warning {{'alloc_align' attribute only applies to return values that are pointers}}
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void *test_ptr_alloc_align(unsigned int a) __attribute__((alloc_align(1))); // no-warning
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int j __attribute__((alloc_align(1))); // expected-warning {{'alloc_align' attribute only applies to non-K&R-style functions}}
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void *test_no_params_zero(void) __attribute__((alloc_align(0))); // expected-error {{'alloc_align' attribute parameter 1 is out of bounds}}
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void *test_no_params(void) __attribute__((alloc_align(1))); // expected-error {{'alloc_align' attribute parameter 1 is out of bounds}}
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void *test_incorrect_param_type(float a) __attribute__((alloc_align(1))); // expected-error {{'alloc_align' attribute argument may only refer to a function parameter of integer type}}
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// argument type
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void *test_bad_param_type(void) __attribute((alloc_align(1.1))); // expected-error {{'alloc_align' attribute requires parameter 1 to be an integer constant}}
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// argument count
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void *test_no_fn_proto(int x, int y) __attribute__((alloc_align)); // expected-error {{'alloc_align' attribute takes one argument}}
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void *test_no_fn_proto(int x, int y) __attribute__((alloc_align())); // expected-error {{'alloc_align' attribute takes one argument}}
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void *test_no_fn_proto(int x, int y) __attribute__((alloc_align(32, 45, 37))); // expected-error {{'alloc_align' attribute takes one argument}}
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void *passthrought(int a) {
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return test_ptr_alloc_align(a);
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}
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void *align16() {
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return test_ptr_alloc_align(16);
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}
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void *align15() {
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return test_ptr_alloc_align(15); // expected-warning {{requested alignment is not a power of 2}}
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}
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void *align1073741824() {
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return test_ptr_alloc_align(2147483648); // expected-warning {{requested alignment must be 1073741824 bytes or smaller; maximum alignment assumed}}
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}
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