[compiler-rt] [ubsan-minimal] Switch to weak symbols for callbacks to allow overriding in client code (PR #119242)

[Kirill Stoimenov via llvm-commits]

https://github.com/kstoimenov updated https://github.com/llvm/llvm-project/pull/119242

>From 15acabf5add7fd15cf58ca2963694e0357e5377a Mon Sep 17 00:00:00 2001
From: Kirill Stoimenov <kstoimenov at google.com>
Date: Fri, 6 Dec 2024 22:05:59 +0000
Subject: [PATCH 1/2] [UBSAN-MINRT] Switch to weak symbols for callbacks to
 allow overriding in client code.

---
 compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp b/compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp
index 53a3273e4e6980..aa91a66cb6d32e 100644
--- a/compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp
+++ b/compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp
@@ -97,8 +97,9 @@ constexpr unsigned kAddrBuf = SANITIZER_WORDSIZE / 4;
 #define MSG_BUF_LEN(msg) (sizeof(MSG_TMPL(msg)) + kAddrBuf + 1)
 
 #define HANDLER_RECOVER(name, msg)                               \
-  INTERFACE void __ubsan_handle_##name##_minimal() {             \
-    uintptr_t caller = GET_CALLER_PC();                  \
+  SANITIZER_INTERFACE_WEAK_DEF(                                  \
+    void, __ubsan_handle_##name##_minimal, void) {               \
+    uintptr_t caller = GET_CALLER_PC();                          \
     if (!report_this_error(caller)) return;                      \
     char msg_buf[MSG_BUF_LEN(msg)] = MSG_TMPL(msg);              \
     decorate_msg(MSG_TMPL_END(msg_buf, msg), caller);            \

>From 6c8ac3b6a5665733d9adc70b88ed34405b3272bc Mon Sep 17 00:00:00 2001
From: Kirill Stoimenov <kstoimenov at google.com>
Date: Mon, 9 Dec 2024 18:21:40 +0000
Subject: [PATCH 2/2] Added a test.

---
 .../ubsan_minimal/TestCases/override-callback.c    | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 compiler-rt/test/ubsan_minimal/TestCases/override-callback.c

diff --git a/compiler-rt/test/ubsan_minimal/TestCases/override-callback.c b/compiler-rt/test/ubsan_minimal/TestCases/override-callback.c
new file mode 100644
index 00000000000000..2893b5df8644ac
--- /dev/null
+++ b/compiler-rt/test/ubsan_minimal/TestCases/override-callback.c
@@ -0,0 +1,14 @@
+// RUN: %clang -fsanitize=implicit-integer-sign-change %s -o %t && %run %t 2>&1 | FileCheck %s --check-prefixes=CHECK
+
+#include <stdio.h>
+#include <stdint.h>
+
+void __ubsan_handle_implicit_conversion_minimal() {
+  printf("CUSTOM_CALLBACK\n");
+}
+
+int main() {
+  int32_t t0 = (~((uint32_t)0));
+// CHECK: CUSTOM_CALLBACK
+  return 0;
+}