[PATCH] middle-end/111818 - failed DECL_NOT_GIMPLE_REG_P setting of volatile

[Richard Biener]

The following addresses a missed DECL_NOT_GIMPLE_REG_P setting of
a volatile declared parameter which causes inlining to substitute
a constant parameter into a context where its address is required.

The main issue is in update_address_taken which clears
DECL_NOT_GIMPLE_REG_P from the parameter but fails to rewrite it
because is_gimple_reg returns false for volatiles.  The following
changes maybe_optimize_var to make the 1:1 correspondence between
clearing DECL_NOT_GIMPLE_REG_P of a register typed decl and
actually rewriting it to SSA.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

        PR middle-end/111818
        * tree-ssa.cc (maybe_optimize_var): When clearing
        DECL_NOT_GIMPLE_REG_P always rewrite into SSA.

        * gcc.dg/torture/pr111818.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr111818.c | 11 +++++++++++
 gcc/tree-ssa.cc                         | 17 +++++++++++------
 2 files changed, 22 insertions(+), 6 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr111818.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr111818.c 
b/gcc/testsuite/gcc.dg/torture/pr111818.c
new file mode 100644
index 00000000000..a7a91111d71
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr111818.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+
+static void foo(const volatile unsigned int x, void *p)
+{
+  __builtin_memcpy(p, (void *)&x, sizeof x);
+}
+
+void bar(void *number)
+{
+  foo(0, number);
+}
diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index ebba02b8449..2f3210fcf61 100644
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -1788,15 +1788,20 @@ maybe_optimize_var (tree var, bitmap addresses_taken, 
bitmap not_reg_needs,
          maybe_reg = true;
          DECL_NOT_GIMPLE_REG_P (var) = 0;
        }
-      if (maybe_reg && is_gimple_reg (var))
+      if (maybe_reg)
        {
-         if (dump_file)
+         if (is_gimple_reg (var))
            {
-             fprintf (dump_file, "Now a gimple register: ");
-             print_generic_expr (dump_file, var);
-             fprintf (dump_file, "\n");
+             if (dump_file)
+               {
+                 fprintf (dump_file, "Now a gimple register: ");
+                 print_generic_expr (dump_file, var);
+                 fprintf (dump_file, "\n");
+               }
+             bitmap_set_bit (suitable_for_renaming, DECL_UID (var));
            }
-         bitmap_set_bit (suitable_for_renaming, DECL_UID (var));
+         else
+           DECL_NOT_GIMPLE_REG_P (var) = 1;
        }
     }
 }
-- 
2.35.3