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bd1c087019
Summary: UB isn't nice. It's cool and powerful, but not nice. Having a way to detect it is nice though. [[ https://wg21.link/p1007r3 | P1007R3: std::assume_aligned ]] / http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r2.pdf says: ``` We propose to add this functionality via a library function instead of a core language attribute. ... If the pointer passed in is not aligned to at least N bytes, calling assume_aligned results in undefined behaviour. ``` This differential teaches clang to sanitize all the various variants of this assume-aligned attribute. Requires D54588 for LLVM IRBuilder changes. The compiler-rt part is D54590. This is a second commit, the original one was r351105, which was mass-reverted in r351159 because 2 compiler-rt tests were failing. Reviewers: ABataev, craig.topper, vsk, rsmith, rnk, #sanitizers, erichkeane, filcab, rjmccall Reviewed By: rjmccall Subscribers: chandlerc, ldionne, EricWF, mclow.lists, cfe-commits, bkramer Tags: #sanitizers Differential Revision: https://reviews.llvm.org/D54589 llvm-svn: 351177
29 lines
982 B
C
29 lines
982 B
C
// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK
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// CHECK-LABEL: @baseline
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void *baseline(void *x) {
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// CHECK: call void @__ubsan_handle_alignment_assumption(
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return __builtin_assume_aligned(x, 1);
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}
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// CHECK-LABEL: blacklist_0
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__attribute__((no_sanitize("undefined"))) void *blacklist_0(void *x) {
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return __builtin_assume_aligned(x, 1);
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}
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// CHECK-LABEL: blacklist_1
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__attribute__((no_sanitize("alignment"))) void *blacklist_1(void *x) {
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return __builtin_assume_aligned(x, 1);
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}
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// CHECK-LABEL: dont_ignore_volatile_ptrs
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void *dont_ignore_volatile_ptrs(void * volatile x) {
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// CHECK: call void @__ubsan_handle_alignment_assumption(
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return __builtin_assume_aligned(x, 1);
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}
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// CHECK-LABEL: ignore_volatiles
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void *ignore_volatiles(volatile void * x) {
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return __builtin_assume_aligned(x, 1);
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}
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