93a8225da1
In case of placement new, if we do not know the alignment of the operand, we can't assume it has the preferred alignment. It might be e.g. a pointer to a struct member which follows ABI alignment rules. This makes UBSAN no longer report "constructor call on misaligned address" when constructing a double into a struct field of type double on i686. The psABI specifies an alignment of 4 bytes, but the preferred alignment used by Clang is 8 bytes. We now use ABI alignment for allocating new as well, as the preferred alignment should be used for over-aligning e.g. local variables, which isn't relevant for ABI code dealing with operator new. AFAICT there wouldn't be problems either way though. Fixes #54845. Differential Revision: https://reviews.llvm.org/D124736
13 lines
414 B
C++
13 lines
414 B
C++
// RUN: %clang_cc1 -triple i686-linux-gnu -emit-llvm %s -o - | FileCheck %s
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// https://github.com/llvm/llvm-project/issues/54845
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void *operator new(unsigned int, void *);
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void test(double *d) {
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// This store used to have an alignment of 8, which was incorrect as
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// the i386 psABI only guarantees a 4-byte alignment for doubles.
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// CHECK: store double 0.000000e+00, {{.*}}, align 4
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new (d) double(0);
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}
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