[gcc(refs/users/aoliva/heads/testme)] strub: drop volatile from wrapper args [PR112938]

[Alexandre Oliva]

https://gcc.gnu.org/g:53d5a5bcd1504d30b789d18f3a19616df2734ef2

commit 53d5a5bcd1504d30b789d18f3a19616df2734ef2
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Mon Dec 11 16:16:45 2023 -0300

    strub: drop volatile from wrapper args [PR112938]
    
    Drop volatile from argument types in internal strub wrappers that are
    not made indirect.  Their volatility is only relevant within the body
    of the function, and that body is moved to the wrapped function.
    
    
    for  gcc/ChangeLog
    
            PR middle-end/112938
            * ipa-strub.cc (pass_ipa_strub::execute): Drop volatile from
            internal strub wrapper args.
    
    for  gcc/testsuite/ChangeLog
    
            PR middle-end/112938
            * gcc.dg/strub-internal-volatile.c: Check for dropped volatile
            in wrapper.

Diff:
---
 gcc/ipa-strub.cc                               | 14 +++++++++++---
 gcc/testsuite/gcc.dg/strub-internal-volatile.c |  5 +++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/gcc/ipa-strub.cc b/gcc/ipa-strub.cc
index 45294b0b46b..bab20c386bb 100644
--- a/gcc/ipa-strub.cc
+++ b/gcc/ipa-strub.cc
@@ -2922,6 +2922,16 @@ pass_ipa_strub::execute (function *)
 	  if (nparmt)
 	    adjust_ftype++;
 	}
+      else if (TREE_THIS_VOLATILE (parm))
+	{
+	  /* Drop volatile from wrapper's arguments, they're just
+	     temporaries copied to the wrapped function.  ???  Should
+	     we drop TYPE_QUAL_ATOMIC as well?  */
+	  TREE_TYPE (parm) = build_qualified_type (TREE_TYPE (parm),
+						   TYPE_QUALS (TREE_TYPE (parm))
+						   & ~TYPE_QUAL_VOLATILE);
+	  TREE_THIS_VOLATILE (parm) = 0;
+	}
 
     /* Also adjust the wrapped function type, if needed.  */
     if (adjust_ftype)
@@ -3224,9 +3234,7 @@ pass_ipa_strub::execute (function *)
 		    {
 		      tree tmp = arg;
 		      /* If ARG is e.g. volatile, we must copy and
-			 convert in separate statements.  ???  Should
-			 we drop volatile from the wrapper
-			 instead?  */
+			 convert in separate statements.  */
 		      if (!is_gimple_val (arg))
 			{
 			  tmp = create_tmp_reg (TYPE_MAIN_VARIANT
diff --git a/gcc/testsuite/gcc.dg/strub-internal-volatile.c b/gcc/testsuite/gcc.dg/strub-internal-volatile.c
index cdfca67616b..0ffa98d799d 100644
--- a/gcc/testsuite/gcc.dg/strub-internal-volatile.c
+++ b/gcc/testsuite/gcc.dg/strub-internal-volatile.c
@@ -1,4 +1,5 @@
 /* { dg-do compile } */
+/* { dg-options "-fdump-ipa-strub" } */
 /* { dg-require-effective-target strub } */
 
 void __attribute__ ((strub("internal")))
@@ -8,3 +9,7 @@ f(volatile short) {
 void g(void) {
   f(0);
 }
+
+/* We drop volatile from the wrapper, and keep it in the wrapped f, so
+   the count remains 1.  */
+/* { dg-final { scan-ipa-dump-times "volatile" 1 "strub" } } */