[patch][PR103033]handle the case when native_interpret_expr return NULL

[Qing Zhao]

Hi, 

PR103033 (c-c++-common/auto-init-4.c ICEs starting with r12-4829)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103033

Is an -ftrivial-auto-var-init bug exposed on Powerpc64-linux only. 

For the following code in gcc/internal-fn.c:

3085		  if (can_native_interpret_type_p (var_type))
3086		    init = native_interpret_expr (var_type, buf, total_bytes);
...
3105	      expand_assignment (lhs, init, false);

there is an inconsistency between "can_native_interpret_type_p" and "native_interpret_expr" for "long double" on Powerpcle: 
although "can_native_interpre_type_p(long double)" return true, "native_interpret_expr (long double, buf,...) return NULL on Powerpcle
Due to the fix for PR95450. 

Therefore, we should expect that “native_interpret_expr” might return NULL, and under such situation, fall though to the more conservative path to
generate “init”

The fix is very simple, and bootstrapped on x86, aarch64, and powerpc. Regression testing are ongoing.

Okay for trunk?

Qing

=====
From 22cf4fee8cf4b050ab41a3de074db70359421b23 Mon Sep 17 00:00:00 2001
From: Qing Zhao <qing.zhao@oracle.com>
Date: Tue, 2 Nov 2021 22:28:13 +0000
Subject: [PATCH] PR 103033 (c-c++-common/auto-init-4.c ICEs starting with
 r12-4829)

Fall through more conservative path to generate patten when
native_interpret_expr return NULL.

gcc/ChangeLog:

2021-11-02  qing zhao  <qing.zhao@oracle.com>

	* internal-fn.c (expand_DEFERRED_INIT): Handle the case when
	native_interpret_expr return NULL.
---
 gcc/internal-fn.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index fd6cb0995d9..0d056fdceea 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3082,9 +3082,8 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
 	  unsigned char *buf = (unsigned char *) xmalloc (total_bytes);
 	  memset (buf, (init_type == AUTO_INIT_PATTERN
 			? INIT_PATTERN_VALUE : 0), total_bytes);
-	  if (can_native_interpret_type_p (var_type))
-	    init = native_interpret_expr (var_type, buf, total_bytes);
-	  else
+	  if (!(can_native_interpret_type_p (var_type)
+		&& (init = native_interpret_expr (var_type, buf, total_bytes))))
 	    {
 	      tree itype = build_nonstandard_integer_type
 			     (total_bytes * BITS_PER_UNIT, 1);
-- 
2.27.0