[PATCH] target/105459 - allow delayed target option node fixup

[PATCH] target/105459 - allow delayed target option node fixup

[Richard Biener]

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.

Bootstrapped and tested on x86_64-unknown-linux-gnu, ok?

Thanks,
Richard.

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.
---
 gcc/config/i386/i386-options.cc       | 32 ++++++++++--------------
 gcc/testsuite/gcc.dg/lto/pr105459_0.c | 35 +++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 19 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/lto/pr105459_0.c

diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index e11f68186f5..acb2291e70f 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -3232,28 +3232,22 @@ 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;
+}
-- 
2.35.3