[Bug rtl-optimization/124383] Should support conditional jump to cold section on x86

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124383

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
          Component|target                      |rtl-optimization
   Last reconfirmed|                            |2026-03-06

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
Something like this:

diff --git a/gcc/bb-reorder.cc b/gcc/bb-reorder.cc
index 4e863bdac99..18d7175972d 100644
--- a/gcc/bb-reorder.cc
+++ b/gcc/bb-reorder.cc
@@ -1666,7 +1666,11 @@ find_rarely_executed_basic_blocks_and_crossing_edges
(void)
     {
       bool cold_bb = false;

-      if (probably_never_executed_bb_p (cfun, bb))
+      /* A basic block isn't cold if it only has one predecessor which
+   isn't cold.  */
+      if (probably_never_executed_bb_p (cfun, bb)
+    && (!single_pred_p (bb)
+        || probably_never_executed_bb_p (cfun, single_pred (bb))))
         {
           cold_bb = true;