[compiler-rt] [sanitizer_common] Fix signal_line.cpp on SPARC (PR #100535)

[Rainer Orth via llvm-commits]

https://github.com/rorth created https://github.com/llvm/llvm-project/pull/100535

```
  SanitizerCommon-ubsan-sparc-Linux :: Linux/signal_line.cpp
```
currently `FAIL`s on Linux/sparc64 (32 and 64-bit) for `n == 2`.  Instead of the expected `SIGSEGV`, the test dies with `SIGBUS`.  `strace` reveals that this is due to a unaligned access:
```
--- SIGBUS {si_signo=SIGBUS, si_code=BUS_ADRALN, si_addr=0x1} ---
```
which is to be expected on a strict-alignment target like SPARC.  Fixed by changing the invalid pointer to be better aligned.

Tested on `sparc64-unknown-linux-gnu` and `x86_64-pc-linux-gnu`.

>From 694e68d77bc31997b954f06100d5f84bd9827780 Mon Sep 17 00:00:00 2001
From: Rainer Orth <ro at gcc.gnu.org>
Date: Thu, 25 Jul 2024 11:08:33 +0200
Subject: [PATCH] [sanitizer_common] Fix signal_line.cpp on SPARC

```
  SanitizerCommon-ubsan-sparc-Linux :: Linux/signal_line.cpp
```
currently `FAIL`s on Linux/sparc64 (32 and 64-bit) for `n == 2`.  Instead
of the expected `SIGSEGV`, the test dies with `SIGBUS`.  `strace` reveals
that this is due to a unaligned access:
```
--- SIGBUS {si_signo=SIGBUS, si_code=BUS_ADRALN, si_addr=0x1} ---
```
which is to be expected on a strict-alignment target like SPARC.  Fixed by
changing the invalid pointer to be better aligned.

Tested on `sparc64-unknown-linux-gnu` and `x86_64-pc-linux-gnu`.
---
 .../test/sanitizer_common/TestCases/Linux/signal_line.cpp      | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler-rt/test/sanitizer_common/TestCases/Linux/signal_line.cpp b/compiler-rt/test/sanitizer_common/TestCases/Linux/signal_line.cpp
index 208ece3e05af4..f1afd859c207a 100644
--- a/compiler-rt/test/sanitizer_common/TestCases/Linux/signal_line.cpp
+++ b/compiler-rt/test/sanitizer_common/TestCases/Linux/signal_line.cpp
@@ -20,7 +20,8 @@ int main(int argc, char **argv) {
   // CHECK1: SUMMARY: [[SAN]]: SEGV {{.*}}signal_line.cpp:[[@LINE-2]]:[[TAB]] in main
 
   if (n == 2)
-    *((volatile int *)0x1) = __LINE__;
+    // Allow for strict-alignment targets that require natural alignment.
+    *((volatile int *)0x8) = __LINE__;
   // CHECK2: #{{[0-9]+ .*}}main {{.*}}signal_line.cpp:[[@LINE-1]]:[[TAB:[0-9]+]]
   // CHECK2: SUMMARY: [[SAN]]: SEGV {{.*}}signal_line.cpp:[[@LINE-2]]:[[TAB]] in main
 }