[gcc(refs/users/aoliva/heads/testme)] strub: enable conditional support

[Alexandre Oliva]

https://gcc.gnu.org/g:b451e34e642677d1f20c161582c7998c88ccf69d

commit b451e34e642677d1f20c161582c7998c88ccf69d
Author: Alexandre Oliva <oliva@gnu.org>
Date:   Wed Dec 6 19:36:02 2023 -0300

    strub: enable conditional support

Diff:
---
 gcc/config/nvptx/nvptx.cc |  3 +++
 gcc/ipa-strub.cc          | 27 +++++++++++++++++++++++++++
 gcc/target.def            |  7 +++++++
 3 files changed, 37 insertions(+)

diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index ae20802c879..3fb1deb70fd 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -7789,6 +7789,9 @@ nvptx_asm_output_def_from_decls (FILE *stream, tree name, tree value)
 #undef TARGET_LIBC_HAS_FUNCTION
 #define TARGET_LIBC_HAS_FUNCTION nvptx_libc_has_function
 
+#undef TARGET_HAVE_STRUB_SUPPORT_FOR
+#define TARGET_HAVE_STRUB_SUPPORT_FOR hook_bool_tree_false
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-nvptx.h"
diff --git a/gcc/ipa-strub.cc b/gcc/ipa-strub.cc
index 293bec132b8..67b4c94db7d 100644
--- a/gcc/ipa-strub.cc
+++ b/gcc/ipa-strub.cc
@@ -60,6 +60,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "ipa-strub.h"
 #include "symtab-thunks.h"
 #include "attr-fnspec.h"
+#include "target.h"
 
 /* This file introduces two passes that, together, implement
    machine-independent stack scrubbing, strub for short.  It arranges
@@ -639,9 +640,35 @@ can_strub_p (cgraph_node *node, bool report = false)
 {
   bool result = true;
 
+  if (!targetm.have_strub_support_for (node->decl))
+    {
+      result = false;
+
+      if (!report)
+	return result;
+
+      sorry_at (DECL_SOURCE_LOCATION (node->decl),
+		"%qD is not eligible for %<strub%>"
+		" on the target system",
+		node->decl);
+    }
+
   if (!report && strub_always_inline_p (node))
     return result;
 
+  if (flag_split_stack)
+    {
+      result = false;
+
+      if (!report)
+	return result;
+
+      sorry_at (DECL_SOURCE_LOCATION (node->decl),
+		"%qD is not eligible for %<strub%>"
+		" because -fsplit-stack is enabled",
+		node->decl);
+    }
+
   if (lookup_attribute ("noipa", DECL_ATTRIBUTES (node->decl)))
     {
       result = false;
diff --git a/gcc/target.def b/gcc/target.def
index 52b83e091b9..11a8a797a05 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -4457,6 +4457,13 @@ otherwise return false.  The default implementation always returns true.",
  bool, (void),
  hook_bool_void_true)
 
+DEFHOOK
+(have_strub_support_for,
+ "Returns true if the target supports stack scrubbing for the given function,\n\
+otherwise return false.  The default implementation always returns true.",
+ bool, (tree),
+ hook_bool_tree_true)
+
 DEFHOOK
 (have_speculation_safe_value,
 "This hook is used to determine the level of target support for\n\