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09a8b7cbc2
Original pull request [here](https://github.com/llvm/llvm-project/pull/108385) Fixes issue https://github.com/llvm/llvm-project/issues/105960 If a member in a struct is also a struct, accessing a member partway through this inner struct currently causes a false positive. This is because when checking aliasing, the access offset is seen as greater than the starting offset of the inner struct, so the loop continues one iteration, and believes we are accessing the member after the inner struct. The next member's offset is greater than the offset we are looking for, so when we subtract the next member's offset from what we are looking for, the offset underflows. To fix this, we check if the member we think we are accessing has a greater offset than the offset we are looking for. If so, we take a step back. We cannot do this in the loop, since the loop does not check the final member. This means the penultimate member would still cause false positives.
50 lines
952 B
C++
50 lines
952 B
C++
// RUN: %clangxx_tysan -O0 %s -o %t && %run %t >%t.out 2>&1
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// RUN: FileCheck %s --implicit-check-not ERROR < %t.out
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// Modified reproducer from https://github.com/llvm/llvm-project/issues/105960
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#include <stdio.h>
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struct inner1 {
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char buffer;
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int i;
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};
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struct inner2 {
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char buffer;
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int i;
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float endBuffer;
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};
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void init_inner1(inner1 *iPtr) { iPtr->i = 200; }
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void init_inner2(inner2 *iPtr) {
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iPtr->i = 400;
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iPtr->endBuffer = 413.0f;
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}
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struct outer {
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inner1 foo;
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inner2 bar;
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char buffer;
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};
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int main(void) {
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outer *l = new outer();
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init_inner1(&l->foo);
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init_inner2(&l->bar);
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int access = l->foo.i;
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printf("Accessed value 1 is %d\n", access);
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access = l->bar.i;
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printf("Accessed value 2 is %d\n", access);
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float fAccess = l->bar.endBuffer;
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printf("Accessed value 3 is %f\n", fAccess);
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return 0;
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}
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// CHECK: Accessed value 1 is 200
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// CHECK: Accessed value 2 is 400
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// CHECK: Accessed value 3 is 413.0
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