test: v8-updates/test-linux-perf-logger fails on loongarch64 - RegExp JIT perf map entries not generated

[SanchezDorso]

Version

v24.14.0

Platform

Linux builder2 6.6.47-12.tl4.loongarch64 #1 SMP loongarch64 GNU/Linux
GCC 12.3.1 (OpenCloudOS 9)

Subsystem

test_runner / v8

What steps will reproduce the bug?

1. Build Node.js v24.14.0 on a loongarch64 host (GCC 12.x).

2. Run the test directly:

   ./node --allow-natives-syntax
   --perf-basic-prof
   --no-turbo-inlining
   --no-opt
   test/fixtures/linux-perf-logger.js

3. Check the generated perf map:

   grep 'RegExp' /tmp/perf-.map

4. Or run the test suite directly:

   ./node test/v8-updates/test-linux-perf-logger.js

How often does it reproduce? Is there a required condition?

100% reproducible on loongarch64.
Required conditions:

• Architecture: loongarch64
• The test must be run on Linux (the test itself skips on non-Linux).
  Does not reproduce on x86_64 or aarch64.

What is the expected behavior? Why is that the expected behavior?

The perf map file /tmp/perf-.map should contain RegExp JIT symbol entries
matching the pattern:

/[a-fA-F0-9]+ [a-fA-F0-9]+.* RegExp.> src: 'test-regex' flags: 'gi'/

This is the behavior observed on x86_64 and aarch64.

What do you see instead?

AssertionError [ERR_ASSERTION]: 2 tests failed

[ERROR 1] --perf-basic-prof interpreted
Errors:

1. Expected to match /[a-fA-F0-9]+ [a-fA-F0-9]+.* RegExp.> src: 'test-regex' flags: 'gi'/
   Perf map content:
   7fffeff03d60 4bc Builtin:DeoptimizationEntry_Eager
   7fffeff04220 4bc Builtin:DeoptimizationEntry_Lazy
   ...（only Builtin: and BytecodeHandler: entries, no RegExp.* entries）

The perf map contains only Builtin:* and BytecodeHandler:* entries.
No RegExp JIT symbol entries are written on loongarch64.

Additional information

Root cause hypothesis:
On loongarch64, V8's RegExp compiler may fall back to the bytecode interpreter
(Irregexp) rather than native code generation, or the PerfJitLogger hook is
not invoked by the loongarch64 regexp code generator. As a result, no JIT
symbol is logged for RegExp compilations.

Workaround used in downstream packaging (OpenCloudOS):
Skip this test specifically on loongarch64 via sed before running the test suite.

Related:

• PR test: skip v8-updates/test-linux-perf-logger #52821 / test: unskip v8-updates/test-linux-perf-logger #52869 — previous skip/unskip cycle for this test
• Issue v8-updates/test-linux-perf no longer works with recent V8 versions #50079 — general test-linux-perf failures with V8 updates

[Xiao-Tao]

Loong64 RegExp macro assembler uses LOG() instead of PROFILE() for code creation events.

File: deps/v8/src/regexp/loong64/regexp-macro-assembler-loong64.cc, function RegExpMacroAssemblerLOONG64::GetCode(),

// Bug: LOG() bypasses perf profiler
LOG(masm_->isolate(),
     RegExpCodeCreateEvent(Cast<AbstractCode>(code), source, flags));

// Fix: Use PROFILE() to hook into perf
PROFILE(masm_->isolate(),
        RegExpCodeCreateEvent(Cast<AbstractCode>(code), source, flags));

diff --git a/deps/v8/src/regexp/loong64/regexp-macro-assembler-loong64.cc b/deps/v8/src/regexp/loong64/regexp-macro-assembler-loong64.cc
index 50865c1473e..0d69963841e 100644
--- a/deps/v8/src/regexp/loong64/regexp-macro-assembler-loong64.cc
+++ b/deps/v8/src/regexp/loong64/regexp-macro-assembler-loong64.cc
@@ -1000,7 +1000,7 @@ DirectHandle<HeapObject> RegExpMacroAssemblerLOONG64::GetCode(
           .set_self_reference(masm_->CodeObject())
           .set_empty_source_position_table()
           .Build();
-  LOG(masm_->isolate(),
+  PROFILE(masm_->isolate(),
       RegExpCodeCreateEvent(Cast<AbstractCode>(code), source, flags));
   return Cast<HeapObject>(code);
 }

• V8 < 14.8: This fix (changing LOG() to PROFILE()) is applicable and resolves the issue.
• V8 ≥ 14.8: The Loong64 architecture issue was unified and fixed via LogCode centrally; no additional patch is needed.

Ref: https://chromium-review.googlesource.com/c/v8/v8/+/7655115

Thanks to the maintainers for investigating this issue.

[SanchezDorso]

Thank you @Xiao-Tao for the precise root cause analysis and the fix.
We have applied the patch in our downstream packaging (OpenCloudOS nodejs24):
The workaround (skipping the test on loongarch64 via sed) has been removed from our packaging. The test-linux-perf-logger.js test should now pass on loongarch64 with Node.js v24.14.0 + this patch applied.