gh-101060: conditionally add -fno-reorder-blocks-and-partition

indygreg · indygreg · commit c2a7c2a418fb · 2023-01-21T10:53:02.000-08:00
The flag isn't implemented on Clang. So we need this so we can
enable BOLT on Clang.
diff --git a/Misc/NEWS.d/next/Build/2023-01-15-11-22-15.gh-issue-101060.0mYk9E.rst b/Misc/NEWS.d/next/Build/2023-01-15-11-22-15.gh-issue-101060.0mYk9E.rst
@@ -0,0 +1,3 @@
+Conditionally add ``-fno-reorder-blocks-and-partition`` in configure.
+Effectively fixes ``--enable-bolt`` when using Clang, as this appears to be
+a GCC-only flag.
diff --git a/configure b/configure
diff --git a/configure.ac b/configure.ac
@@ -2015,8 +2015,13 @@ if test "$Py_BOLT" = 'true' ; then
   DEF_MAKE_ALL_RULE="bolt-opt"
   DEF_MAKE_RULE="build_all"
 
+  # -fno-reorder-blocks-and-partition is required for bolt to work.
+  # Possibly GCC only.
+  AX_CHECK_COMPILE_FLAG([-fno-reorder-blocks-and-partition],[
+      CFLAGS_NODIST="$CFLAGS_NODIST -fno-reorder-blocks-and-partition"
+  ])
+
   # These flags are required for bolt to work:
-  CFLAGS_NODIST="$CFLAGS_NODIST -fno-reorder-blocks-and-partition"
   LDFLAGS_NODIST="$LDFLAGS_NODIST -Wl,--emit-relocs"
 
   # These flags are required to get good performance from bolt:

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+Conditionally add ``-fno-reorder-blocks-and-partition`` in configure.
	`2`	+Effectively fixes ``--enable-bolt`` when using Clang, as this appears to be
	`3`	`+a GCC-only flag.`