[lldb][test][NFC] Add LLDB test for UBSan trap frame recognizer #151231

anthonyhatran · 2025-07-29T21:08:42Z

In #145967 Clang was taught to emit trap reasons on UBSan traps in debug info using the same method as __builtin_verbose_trap. This patch adds a test case to make sure that the existing "Verbose Trap StackFrame Recognizer" recognizes the trap reason and sets the stop reason and stack frame appropriately.

Part of a GSoC 2025 Project.

llvmbot · 2025-07-29T21:09:16Z

@llvm/pr-subscribers-lldb

Author: Anthony Tran (anthonyhatran)

Changes

@Michael137 @delcypher

Part of a GSoC 2025 Project.

Full diff: https://github.com/llvm/llvm-project/pull/151231.diff

2 Files Affected:

(added) lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp (+8)
(added) lldb/test/Shell/Recognizer/ubsan_add_overflow.test (+17)

diff --git a/lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp b/lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp
new file mode 100644
index 0000000000000..0258ff296ea63
--- /dev/null
+++ b/lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp
@@ -0,0 +1,8 @@
+#include <limits.h>
+
+int main() {
+  volatile int a = INT_MAX;
+  volatile int b = 1;
+  volatile int c = a + b;
+  return c;
+}
\ No newline at end of file
diff --git a/lldb/test/Shell/Recognizer/ubsan_add_overflow.test b/lldb/test/Shell/Recognizer/ubsan_add_overflow.test
new file mode 100644
index 0000000000000..f9312b5bf15bb
--- /dev/null
+++ b/lldb/test/Shell/Recognizer/ubsan_add_overflow.test
@@ -0,0 +1,17 @@
+# REQUIRES: clang
+
+# RUN: %clang_host -g -O0 %S/Inputs/ubsan_add_overflow.cpp -o %t.out \
+# RUN: -fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow
+
+# RUN: %lldb -b -s %s %t.out | FileCheck %s
+
+run
+# CHECK: thread #{{.*}} stop reason = Undefined Behavior Sanitizer: Integer addition overflowed
+
+frame info
+# CHECK: frame #{{.*}}`main at ubsan_add_overflow.cpp
+
+frame recognizer info 0
+# CHECK: frame 0 is recognized by Verbose Trap StackFrame Recognizer
+
+quit
\ No newline at end of file

DavidSpickett · 2025-07-30T08:13:26Z

FYI I put the tagged people in reviewers for you (GitHub probably isn't letting you do that yourself, at some point you'll get permissions to do so). This way we don't land this with @ s in there and create an endless series of pings as llvm forks pull in this change.

Myself I usually put any review process related comments in my first comment after the PR is opened, keeps the description clean.

Michael137 · 2025-07-30T08:21:09Z

lldb/test/Shell/Recognizer/ubsan_add_overflow.test

+# REQUIRES: clang
+
+# RUN: %clang_host -g -O0 %S/Inputs/ubsan_add_overflow.cpp -o %t.out \
+# RUN: -fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow


Lets indent here to make it easier to read

Suggested change

# RUN: -fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow

# RUN: -fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow

DavidSpickett

Some comments since I'm here but I leave it to your chosen reviewers to do the rest.

DavidSpickett · 2025-07-30T08:15:57Z

lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp

+  volatile int a = INT_MAX;
+  volatile int b = 1;
+  volatile int c = a + b;
+  return c;


I think this could be done in one line. return INT_MAX + 1; assuming INT_MAX defaults to unsigned int still.

Made it into one line.

lldb/test/Shell/Recognizer/ubsan_add_overflow.test

lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp

DavidSpickett · 2025-07-30T08:24:12Z

Also surprised that we didn't have tests for this already, but I presume that's why you are contributing this now.

DavidSpickett · 2025-07-30T08:25:27Z

lldb/test/Shell/Recognizer/ubsan_add_overflow.test

@@ -0,0 +1,17 @@
+# REQUIRES: clang
+
+# RUN: %clang_host -g -O0 %S/Inputs/ubsan_add_overflow.cpp -o %t.out \


Also I have a feeling this doesn't need to be host, because the shell tests can be run remotely. I looked at the other tests and they are all %clang_host though.

So this is not an issue with this test it's with a category of tests. Which is not your responsibility, so you don't need to change anything here.

Michael137 · 2025-07-30T08:27:42Z

Also surprised that we didn't have tests for this already, but I presume that's why you are contributing this now.

There are tests for the __builtin_verbose_trap builtin, which was the only way Clang used to emit the artificial frames for LLDB to recognize. After #145967 we now also emit those fake frames for ubsan traps. The test added here ensures the UBSAN traps get recognized by LLDB

@anthonyhatran lets put this context into the PR description

delcypher

Mostly looks good. Please remove the uses of volatile unless there's a good reason for them to be there. Also please make the description/commit message be more descriptive. Something like

[lldb][NFC] Add test cases for UBSan trap reasons

In #145967 Clang was taught to emit trap reasons on UBSan traps in debug info using the same method as __builtin_verbose_trap. This patch adds a test case to make sure that the existing "Verbose Trap StackFrame Recognizer" recognizes the trap reason and sets the stop reason and stack frame appropriately.

lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp

lldb/test/Shell/Recognizer/ubsan_add_overflow.test

delcypher · 2025-07-30T22:16:21Z

lldb/test/Shell/Recognizer/ubsan_add_overflow.test


-frame info


@anthonyhatran You should keep the frame info command and checking the output because this checks that the selected frame is in main and not the fake frame.

To be clear. What you added (bt and checking the output) is good but we should also make sure that frame 1 is the selected frame.

Thanks for the clarification; I thought it would be potentially redundant so I removed it. I also didn't see Michael's comment before the initial revision commit. Re-added.

dzhidzhoev · 2025-07-31T07:45:03Z

Apparently, these changes break lldb-x86_64-win buildbot with the following error:

C:\buildbot\as-builder-10\lldb-x86-64\llvm-project\lldb\test\Shell\Recognizer\ubsan_add_overflow.test:7:10: error: CHECK: expected string not found in input
# | # CHECK: thread #{{.*}} stop reason = Undefined Behavior Sanitizer: Integer addition overflowed
# |          ^

https://lab.llvm.org/buildbot/#/builders/211/builds/945/steps/10/logs/stdio

https://lab.llvm.org/buildbot/#/builders/211/builds/945

Could you please take a look at it?

Michael137 · 2025-07-31T07:59:26Z

Apparently, these changes break lldb-x86_64-win buildbot with the following error:
C:\buildbot\as-builder-10\lldb-x86-64\llvm-project\lldb\test\Shell\Recognizer\ubsan_add_overflow.test:7:10: error: CHECK: expected string not found in input
# | # CHECK: thread #{{.*}} stop reason = Undefined Behavior Sanitizer: Integer addition overflowed
# |          ^
https://lab.llvm.org/buildbot/#/builders/211/builds/945/steps/10/logs/stdio

https://lab.llvm.org/buildbot/#/builders/211/builds/945

Could you please take a look at it?

I skipped it on Windows in 21bf2fa

anthonyhatran requested a review from JDevlieghere as a code owner July 29, 2025 21:08

llvmbot added the lldb label Jul 29, 2025

Add test for UBSan trap frame recognizer

bdf7487

anthonyhatran force-pushed the ubsan-lldb-stop-reason-test branch from bb76775 to bdf7487 Compare July 29, 2025 21:10

DavidSpickett requested review from Michael137 and delcypher July 30, 2025 08:11

Michael137 reviewed Jul 30, 2025

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Michael137 approved these changes Jul 30, 2025

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DavidSpickett reviewed Jul 30, 2025

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DavidSpickett changed the title ~~[lldb] Add LLDB test for UBSan trap frame recognizer~~ [lldb][test] Add LLDB test for UBSan trap frame recognizer Jul 30, 2025

DavidSpickett reviewed Jul 30, 2025

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delcypher approved these changes Jul 30, 2025

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lldb/test/Shell/Recognizer/Inputs/ubsan_add_overflow.cpp Outdated Show resolved Hide resolved

delcypher requested changes Jul 30, 2025

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lldb/test/Shell/Recognizer/ubsan_add_overflow.test Outdated Show resolved Hide resolved

Address all comments

3623b01

delcypher reviewed Jul 30, 2025

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Re-add frame info line

f2f1b62

anthonyhatran changed the title ~~[lldb][test] Add LLDB test for UBSan trap frame recognizer~~ [lldb][test][NFC] Add LLDB test for UBSan trap frame recognizer Jul 30, 2025

delcypher approved these changes Jul 31, 2025

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delcypher merged commit a8d0ae3 into llvm:main Jul 31, 2025
9 checks passed

	# RUN: -fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow
	# RUN: -fsanitize=signed-integer-overflow -fsanitize-trap=signed-integer-overflow

		@@ -0,0 +1,17 @@
		# REQUIRES: clang

		# RUN: %clang_host -g -O0 %S/Inputs/ubsan_add_overflow.cpp -o %t.out \

[lldb][test][NFC] Add LLDB test for UBSan trap frame recognizer #151231

[lldb][test][NFC] Add LLDB test for UBSan trap frame recognizer #151231

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