2021-01-19  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/98721
	* builtins.c (access_ref::inform_access): Don't assume
	SSA_NAME_IDENTIFIER must be non-NULL.  Print messages about
	object whenever allocfn is NULL, rather than only when DECL_P
	is true.  Use %qE instead of %qD for that.  Formatting fixes.

	* gcc.dg/pr98721-1.c: New test.
	* gcc.dg/pr98721-2.c: New test.

--- gcc/builtins.c.jj	2021-01-18 19:07:16.022895507 +0100
+++ gcc/builtins.c	2021-01-19 11:56:52.247070923 +0100
@@ -4414,8 +4414,8 @@ access_ref::inform_access (access_mode m
 	 MAXREF on which the result is based.  */
       const offset_int orng[] =
 	{
-	 offrng[0] - maxref.offrng[0],
-	 wi::smax (offrng[1] - maxref.offrng[1], offrng[0]),
+	  offrng[0] - maxref.offrng[0],
+	  wi::smax (offrng[1] - maxref.offrng[1], offrng[0]),
 	};
 
       /* Add the final PHI's offset to that of each of the arguments
@@ -4493,12 +4493,15 @@ access_ref::inform_access (access_mode m
 	      /* Strip the SSA_NAME suffix from the variable name and
 		 recreate an identifier with the VLA's original name.  */
 	      ref = gimple_call_lhs (stmt);
-	      ref = SSA_NAME_IDENTIFIER (ref);
-	      const char *id = IDENTIFIER_POINTER (ref);
-	      size_t len = strcspn (id, ".$");
-	      if (!len)
-		len = strlen (id);
-	      ref = get_identifier_with_length (id, len);
+	      if (SSA_NAME_IDENTIFIER (ref))
+		{
+		  ref = SSA_NAME_IDENTIFIER (ref);
+		  const char *id = IDENTIFIER_POINTER (ref);
+		  size_t len = strcspn (id, ".$");
+		  if (!len)
+		    len = strlen (id);
+		  ref = get_identifier_with_length (id, len);
+		}
 	    }
 	  else
 	    {
@@ -4557,13 +4560,13 @@ access_ref::inform_access (access_mode m
       return;
     }
 
-  if (DECL_P (ref))
+  if (allocfn == NULL_TREE)
     {
       if (*offstr)
-	inform (loc, "at offset %s into source object %qD of size %s",
+	inform (loc, "at offset %s into source object %qE of size %s",
 		offstr, ref, sizestr);
       else
-	inform (loc, "source object %qD of size %s", ref,  sizestr);
+	inform (loc, "source object %qE of size %s", ref, sizestr);
 
       return;
     }
--- gcc/testsuite/gcc.dg/pr98721-1.c.jj	2021-01-19 12:15:03.825600828 +0100
+++ gcc/testsuite/gcc.dg/pr98721-1.c	2021-01-19 12:14:24.730045488 +0100
@@ -0,0 +1,14 @@
+/* PR tree-optimization/98721 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int
+foo (int n)
+{
+  if (n <= 0)
+    {
+      char vla[n];			/* { dg-message "source object 'vla' of size 0" } */
+      return __builtin_strlen (vla);	/* { dg-warning "'__builtin_strlen' reading 1 or more bytes from a region of size 0" } */
+    }
+  return -1;
+}
--- gcc/testsuite/gcc.dg/pr98721-2.c.jj	2021-01-19 12:00:16.005742548 +0100
+++ gcc/testsuite/gcc.dg/pr98721-2.c	2021-01-19 11:59:29.372275423 +0100
@@ -0,0 +1,8 @@
+/* PR tree-optimization/98721 */
+/* { dg-do compile } */
+
+int
+foo (void)
+{
+  return __builtin_strlen (__builtin_alloca_with_align (0, 16));	/* { dg-warning "'__builtin_strlen' reading 1 or more bytes from a region of size 0" } */
+}	/* { dg-message "source object '<unknown>' of size 0" "" { target *-*-* } .-1 } */