[gcc r12-8576] target/105459 - allow delayed target option node fixup

[gcc r12-8576] target/105459 - allow delayed target option node fixup

[Richard Biener]

https://gcc.gnu.org/g:4ed850a568e4d27a2df566f13843714ca80d437e

commit r12-8576-g4ed850a568e4d27a2df566f13843714ca80d437e
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Jul 1 14:11:35 2022 +0200

    target/105459 - allow delayed target option node fixup
    
    The following avoids the need to massage the target optimization
    node at WPA time when we fixup the optimization node, copying
    FP related flags from callee to caller.  The target is already
    set up to fixup, but that only works when not switching between
    functions.  After fixing that the fixup is then done at LTRANS
    time when materializing the function.
    
    2022-07-01  Richard Biener  <rguenthert@suse.de>
    
            PR target/105459
            * config/i386/i386-options.cc (ix86_set_current_function):
            Rebuild the target optimization node whenever necessary,
            not only when the optimization node didn't change.
    
            * gcc.dg/lto/pr105459_0.c: New testcase.
    
    (cherry picked from commit 4c94382a132a4b2b9d020806549a006fa6764d1b)

Diff:
---
 gcc/config/i386/i386-options.cc       | 32 +++++++++++++-------------------
 gcc/testsuite/gcc.dg/lto/pr105459_0.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 19 deletions(-)

diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index 32cc58a764b..706be5a60b8 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -3229,28 +3229,22 @@ ix86_set_current_function (tree fndecl)
   if (new_tree == NULL_TREE)
     new_tree = target_option_default_node;
 
-  if (old_tree != new_tree)
+  bool fp_flag_change
+    = (flag_unsafe_math_optimizations
+       != TREE_TARGET_OPTION (new_tree)->x_ix86_unsafe_math_optimizations
+       || (flag_excess_precision
+	   != TREE_TARGET_OPTION (new_tree)->x_ix86_excess_precision));
+  if (old_tree != new_tree || fp_flag_change)
     {
       cl_target_option_restore (&global_options, &global_options_set,
 				TREE_TARGET_OPTION (new_tree));
-      if (TREE_TARGET_GLOBALS (new_tree))
-	restore_target_globals (TREE_TARGET_GLOBALS (new_tree));
-      else if (new_tree == target_option_default_node)
-	restore_target_globals (&default_target_globals);
-      else
-	TREE_TARGET_GLOBALS (new_tree) = save_target_globals_default_opts ();
-    }
-  else if (flag_unsafe_math_optimizations
-	   != TREE_TARGET_OPTION (new_tree)->x_ix86_unsafe_math_optimizations
-	   || (flag_excess_precision
-	       != TREE_TARGET_OPTION (new_tree)->x_ix86_excess_precision))
-    {
-      cl_target_option_restore (&global_options, &global_options_set,
-				TREE_TARGET_OPTION (new_tree));
-      ix86_excess_precision = flag_excess_precision;
-      ix86_unsafe_math_optimizations = flag_unsafe_math_optimizations;
-      DECL_FUNCTION_SPECIFIC_TARGET (fndecl) = new_tree
-	= build_target_option_node (&global_options, &global_options_set);
+      if (fp_flag_change)
+	{
+	  ix86_excess_precision = flag_excess_precision;
+	  ix86_unsafe_math_optimizations = flag_unsafe_math_optimizations;
+	  DECL_FUNCTION_SPECIFIC_TARGET (fndecl) = new_tree
+	    = build_target_option_node (&global_options, &global_options_set);
+	}
       if (TREE_TARGET_GLOBALS (new_tree))
 	restore_target_globals (TREE_TARGET_GLOBALS (new_tree));
       else if (new_tree == target_option_default_node)
diff --git a/gcc/testsuite/gcc.dg/lto/pr105459_0.c b/gcc/testsuite/gcc.dg/lto/pr105459_0.c
new file mode 100644
index 00000000000..c799e6ef23d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr105459_0.c
@@ -0,0 +1,35 @@
+/* { dg-lto-do link } */
+/* { dg-lto-options { { -flto -O1 } } } */
+
+double m;
+int n;
+
+__attribute__ ((optimize ("-funsafe-math-optimizations")))
+void
+bar (int x)
+{
+  n = x;
+  m = n;
+}
+
+__attribute__ ((flatten))
+void
+foo (int x)
+{
+  bar (x);
+}
+
+void
+quux (void)
+{
+  ++n;
+}
+
+int
+main (void)
+{
+  foo (0);
+  quux ();
+
+  return 0;
+}