avoid hardreg autoinit

This avoids initializating "uninitialized" hardregs like SP.

2021-10-04  Richard Biener  <rguenther@suse.de>

	* gimplify.c (is_var_need_auto_init): DECL_HARD_REGISTER
	variables are not to be initialized.

	* gcc.dg/auto-init-hardreg-1.c: New testcase.

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index f4bc649..b27776a 100644 (file)
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -1825,6 +1825,8 @@ static bool
 is_var_need_auto_init (tree decl)
 {
   if (auto_var_p (decl)
+      && (TREE_CODE (decl) != VAR_DECL
+         || !DECL_HARD_REGISTER (decl))
       && (flag_auto_var_init > AUTO_INIT_UNINITIALIZED)
       && (!lookup_attribute ("uninitialized", DECL_ATTRIBUTES (decl)))
       && !is_empty_type (TREE_TYPE (decl)))

diff --git a/gcc/testsuite/gcc.dg/auto-init-hardreg-1.c b/gcc/testsuite/gcc.dg/auto-init-hardreg-1.c
new file mode 100644 (file)
index 0000000..7c9de99
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/auto-init-hardreg-1.c
@@ -0,0 +1,9 @@
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-ftrivial-auto-var-init=zero" } */
+
+int
+main ()
+{
+  register long *sp __asm__("sp");
+  return 0;
+}