PR 102281 (-ftrivial-auto-var-init=zero causes ice)

Do not add call to __builtin_clear_padding when a variable is a gimple
register or it might not have padding.

gcc/ChangeLog:

2021-11-01  qing zhao  <qing.zhao@oracle.com>

	* gimplify.c (gimplify_decl_expr): Do not add call to
	__builtin_clear_padding when a variable is a gimple register
	or it might not have padding.
	(gimplify_init_constructor): Likewise.

gcc/testsuite/ChangeLog:

2021-11-01  qing zhao  <qing.zhao@oracle.com>

	* c-c++-common/pr102281.c: New test.
	* gcc.target/i386/auto-init-2.c: Adjust testing case.
	* gcc.target/i386/auto-init-4.c: Likewise.
	* gcc.target/i386/auto-init-6.c: Likewise.
	* gcc.target/aarch64/auto-init-6.c: Likewise.

1 files changed, 19 insertions, 6 deletions

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 8bb54fd..c2ab96e 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -1784,8 +1784,8 @@ gimple_add_init_for_auto_var (tree decl,
    that padding is initialized to zero. So, we always initialize paddings
    to zeroes regardless INIT_TYPE.
    To do the padding initialization, we insert a call to
-   __BUILTIN_CLEAR_PADDING (&decl, 0, for_auto_init = true).
-   Note, we add an additional dummy argument for __BUILTIN_CLEAR_PADDING,
+   __builtin_clear_padding (&decl, 0, for_auto_init = true).
+   Note, we add an additional dummy argument for __builtin_clear_padding,
    'for_auto_init' to distinguish whether this call is for automatic
    variable initialization or not.
    */
@@ -1954,8 +1954,14 @@ gimplify_decl_expr (tree *stmt_p, gimple_seq *seq_p)
 	     pattern initialization.
 	     In order to make the paddings as zeroes for pattern init, We
 	     should add a call to __builtin_clear_padding to clear the
-	     paddings to zero in compatiple with CLANG.  */
-	  if (flag_auto_var_init == AUTO_INIT_PATTERN)
+	     paddings to zero in compatiple with CLANG.
+	     We cannot insert this call if the variable is a gimple register
+	     since __builtin_clear_padding will take the address of the
+	     variable.  As a result, if a long double/_Complex long double
+	     variable will spilled into stack later, its padding is 0XFE.  */
+	  if (flag_auto_var_init == AUTO_INIT_PATTERN
+	      && !is_gimple_reg (decl)
+	      && clear_padding_type_may_have_padding_p (TREE_TYPE (decl)))
 	    gimple_add_padding_init_for_auto_var (decl, is_vla, seq_p);
 	}
     }
@@ -5384,12 +5390,19 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
 
   /* If the user requests to initialize automatic variables, we
      should initialize paddings inside the variable.  Add a call to
-     __BUILTIN_CLEAR_PADDING (&object, 0, for_auto_init = true) to
+     __builtin_clear_pading (&object, 0, for_auto_init = true) to
      initialize paddings of object always to zero regardless of
      INIT_TYPE.  Note, we will not insert this call if the aggregate
      variable has be completely cleared already or it's initialized
-     with an empty constructor.  */
+     with an empty constructor.  We cannot insert this call if the
+     variable is a gimple register since __builtin_clear_padding will take
+     the address of the variable.  As a result, if a long double/_Complex long
+     double variable will be spilled into stack later, its padding cannot
+     be cleared with __builtin_clear_padding.  We should clear its padding
+     when it is spilled into memory.  */
   if (is_init_expr
+      && !is_gimple_reg (object)
+      && clear_padding_type_may_have_padding_p (type)
       && ((AGGREGATE_TYPE_P (type) && !cleared && !is_empty_ctor)
 	  || !AGGREGATE_TYPE_P (type))
       && is_var_need_auto_init (object))