Skip to content

[3.14] gh-148284: Block inlining of gigantic functions in ceval.c for clang 22 #148326

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
Fidget-Spinner wants to merge 4 commits into from
+81 −0
Closed

[3.14] gh-148284: Block inlining of gigantic functions in ceval.c for clang 22 #148326

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
012b8a9
Block inlining of gigantic functions
Fidget-Spinner Apr 10, 2026
144522b
📜🤖 Added by blurb_it.
blurb-it[bot] Apr 10, 2026
9e14d47
remove unused function
Fidget-Spinner Apr 10, 2026
ce5594f
Merge branch 'block_inlining_of_gigantic_functions' of github.com:Fid…
Fidget-Spinner Apr 10, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions Makefile.pre.in
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -126,6 +126,8 @@ PY_CORE_CFLAGS= $(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE
PY_CORE_LDFLAGS=$(PY_LDFLAGS) $(PY_LDFLAGS_NODIST)
# Strict or non-strict aliasing flags used to compile dtoa.c, see above
CFLAGS_ALIASING=@CFLAGS_ALIASING@
# Compilation flags only for ceval.c.
CFLAGS_CEVAL=@CFLAGS_CEVAL@


# Machine-dependent subdirectories
Expand Down Expand Up @@ -3142,6 +3144,9 @@ regen-jit:
Python/dtoa.o: Python/dtoa.c
$(CC) -c $(PY_CORE_CFLAGS) $(CFLAGS_ALIASING) -o $@ $<

Python/ceval.o: Python/ceval.c
$(CC) -c $(PY_CORE_CFLAGS) $(CFLAGS_CEVAL) -o $@ $<

# Run reindent on the library
.PHONY: reindent
reindent:
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-04-10-09-21-40.gh-issue-148284.6xMH49.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix high stack consumption in Python's interpreter loop on Clang 22 by setting function limits for inlining.
47 changes: 47 additions & 0 deletions configure
View file
Open in desktop

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

28 changes: 28 additions & 0 deletions configure.ac
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7244,6 +7244,34 @@ if test "$have_glibc_memmove_bug" = yes; then
for memmove and bcopy.])
fi

AC_MSG_CHECKING([if we need to manually block large inlining in ceval.c])
AC_RUN_IFELSE([AC_LANG_SOURCE([[
int main(void) {
// See gh-148284:
// Clang 22 seems to have interactions with inlining and the stackref buffer
// which cause 40kB of stack usage on x86-64 in buggy versions of _PyEval_EvalFrameDefault
// in computed goto interpreter. The normal usage seen is normally 1-2kB.
Comment on lines +7250 to +7253
Copy link
Copy Markdown
Member

@vstinner vstinner Apr 10, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Reformat to 80 columns and minor cleanup:

Suggested change
// See gh-148284:
// Clang 22 seems to have interactions with inlining and the stackref buffer
// which cause 40kB of stack usage on x86-64 in buggy versions of _PyEval_EvalFrameDefault
// in computed goto interpreter. The normal usage seen is normally 1-2kB.
// See gh-148284: Clang 22 seems to have interactions with inlining
// and the stackref buffer which cause 40 kB of stack usage on x86-64
// in buggy versions of _PyEval_EvalFrameDefault() in computed goto
// interpreter. The normal usage seen is normally 1-2 kB.

#if defined(__clang__) && (__clang_major__ == 22)
return 1;
#else
return 0;
#endif
}
]])],
[block_huge_inlining_in_ceval=no],
[block_huge_inlining_in_ceval=yes],
[block_huge_inlining_in_ceval=undefined])
AC_MSG_RESULT([$block_huge_inlining_in_ceval])

if test "$block_huge_inlining_in_ceval" = yes && test "$ac_cv_computed_gotos" = yes; then
// This number should be tuned to follow the C stack consumption
// in _PyEval_EvalFrameDefault on computed goto interpreter.
Comment on lines +7267 to +7268
Copy link
Copy Markdown
Member

@vstinner vstinner Apr 10, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I suggest adding "Suppress inlining of functions whose stack size exceeds 512 bytes." to explain the purpose of this option:

Suggested change
// This number should be tuned to follow the C stack consumption
// in _PyEval_EvalFrameDefault on computed goto interpreter.
// gh-148284: Suppress inlining of functions whose stack size exceeds
// 512 bytes. This number should be tuned to follow the C stack
// consumption in _PyEval_EvalFrameDefault() on computed goto
// interpreter.

The Clang option is documented at: https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-finline-max-stacksize

CFLAGS_CEVAL="-finline-max-stacksize=512"
else
CFLAGS_CEVAL=""
fi
AC_SUBST([CFLAGS_CEVAL])
Copy link
Copy Markdown
Member

@vstinner vstinner Apr 10, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can you document this new variable in https://docs.python.org/dev/using/configure.html#envvar-CFLAGS_ALIASING ?

Copy link
Copy Markdown
Member Author

@Fidget-Spinner Fidget-Spinner Apr 10, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Is there a way to make this a private variable? I don't feel good exposing it for now.


if test "$ac_cv_gcc_asm_for_x87" = yes; then
# Some versions of gcc miscompile inline asm:
# http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46491
Expand Down
Loading