[3.14] gh-145801: Use gcc -fprofile-update=atomic for PGO builds (GH-145802) (#145892)

gh-145801: Use gcc -fprofile-update=atomic for PGO builds (GH-145802)

When Python build is optimized with GCC using PGO, use
-fprofile-update=atomic option to use atomic operations when updating
profile information. This option reduces the risk of gcov Data Files
(.gcda) corruption which can cause random GCC crashes.
(cherry picked from commit 08a018ebe0d673e9c352f790d2e4604d69604188)

Co-authored-by: Victor Stinner <vstinner@python.org>

diff --git a/Misc/NEWS.d/next/Build/2026-03-11-11-58-42.gh-issue-145801.iCXa3v.rst b/Misc/NEWS.d/next/Build/2026-03-11-11-58-42.gh-issue-145801.iCXa3v.rst
new file mode 100644 (file)
index 0000000..c5f3982
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2026-03-11-11-58-42.gh-issue-145801.iCXa3v.rst
@@ -0,0 +1,4 @@
+When Python build is optimized with GCC using PGO, use
+``-fprofile-update=atomic`` option to use atomic operations when updating
+profile information. This option reduces the risk of gcov Data Files (.gcda)
+corruption which can cause random GCC crashes. Patch by Victor Stinner.

diff --git a/configure b/configure
index 60a88b29b538dab90617d236cbb63e3034340b99..3e507be82c046a11701aecff82050e62a7c793d5 100755 (executable)
--- a/configure
+++ b/configure
@@ -9049,7 +9049,47 @@ case "$ac_cv_cc_name" in
     fi
     ;;
   gcc)
-    PGO_PROF_GEN_FLAG="-fprofile-generate"
+    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -fprofile-update=atomic" >&5
+printf %s "checking whether C compiler accepts -fprofile-update=atomic... " >&6; }
+if test ${ax_cv_check_cflags___fprofile_update_atomic+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e)
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  -fprofile-update=atomic"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main (void)
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+  ax_cv_check_cflags___fprofile_update_atomic=yes
+else case e in #(
+  e) ax_cv_check_cflags___fprofile_update_atomic=no ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___fprofile_update_atomic" >&5
+printf "%s\n" "$ax_cv_check_cflags___fprofile_update_atomic" >&6; }
+if test "x$ax_cv_check_cflags___fprofile_update_atomic" = xyes
+then :
+  PGO_PROF_GEN_FLAG="-fprofile-generate -fprofile-update=atomic"
+else case e in #(
+  e) PGO_PROF_GEN_FLAG="-fprofile-generate" ;;
+esac
+fi
+
     PGO_PROF_USE_FLAG="-fprofile-use -fprofile-correction"
     LLVM_PROF_MERGER="true"
     LLVM_PROF_FILE=""

diff --git a/configure.ac b/configure.ac
index ec93a7438172685d0426f75af183653093fd0c8e..a1f4a5670957be5c83c720e845cc5a414d1f4cc0 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -2072,7 +2072,10 @@ case "$ac_cv_cc_name" in
     fi
     ;;
   gcc)
-    PGO_PROF_GEN_FLAG="-fprofile-generate"
+    AX_CHECK_COMPILE_FLAG(
+        [-fprofile-update=atomic],
+        [PGO_PROF_GEN_FLAG="-fprofile-generate -fprofile-update=atomic"],
+        [PGO_PROF_GEN_FLAG="-fprofile-generate"])
     PGO_PROF_USE_FLAG="-fprofile-use -fprofile-correction"
     LLVM_PROF_MERGER="true"
     LLVM_PROF_FILE=""