re PR c/87387 (trunk/gcc/builtins.c:585:7: warning: -Wself-assign problem)

	PR c/87387
        * builtins.c (unterminated_array): Simplify.
	* expr.c (string_constant): Handle SSA_NAME.  Add more exceptions
	where pointer arithmetic is safe.

	* gcc.dg/warn-stpcpy-no-nul.c: Drop unnecessary xfails.
	* gcc.dg/warn-stplen-no-nul.c: Likewise.

From-SVN: r264585

gcc/ChangeLog

+2018-09-25  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	PR c/87387
+        * builtins.c (unterminated_array): Simplify.
+	* expr.c (string_constant): Handle SSA_NAME.  Add more exceptions
+	where pointer arithmetic is safe.
+
 2018-09-25  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	PR target/86987

gcc/builtins.c

@@ -570,28 +570,9 @@ warn_string_no_nul (location_t loc, const char *fn, tree arg, tree decl)
 tree
 unterminated_array (tree exp)
 {
-  if (TREE_CODE (exp) == SSA_NAME)
-    {
-      gimple *stmt = SSA_NAME_DEF_STMT (exp);
-      if (!is_gimple_assign (stmt))
-	return NULL_TREE;
-
-      tree rhs1 = gimple_assign_rhs1 (stmt);
-      tree_code code = gimple_assign_rhs_code (stmt);
-      if (code == ADDR_EXPR
-	  && TREE_CODE (TREE_OPERAND (rhs1, 0)) == ARRAY_REF)
-	rhs1 = rhs1;
-      else if (code != POINTER_PLUS_EXPR)
-	return NULL_TREE;
-
-      exp = rhs1;
-    }
-
   tree nonstr = NULL;
-  if (c_strlen (exp, 1, &nonstr, 1) == NULL && nonstr)
-    return nonstr;
-
-  return NULL_TREE;
+  c_strlen (exp, 1, &nonstr);
+  return nonstr;
 }
 
 /* Compute the length of a null-terminated character string or wide

gcc/expr.c

@@ -11372,7 +11372,10 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
 	  /* Avoid pointers to arrays (see bug 86622).  */
 	  if (POINTER_TYPE_P (TREE_TYPE (arg))
 	      && TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) == ARRAY_TYPE
-	      && TREE_CODE (TREE_OPERAND (arg0, 0)) == ARRAY_REF)
+	      && !(decl && !*decl)
+	      && !(decl && tree_fits_uhwi_p (DECL_SIZE_UNIT (*decl))
+		   && mem_size && tree_fits_uhwi_p (*mem_size)
+		   && tree_int_cst_equal (*mem_size, DECL_SIZE_UNIT (*decl))))
 	    return NULL_TREE;
 
 	  tree type = TREE_TYPE (arg1);
@@ -11381,6 +11384,38 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
 	}
       return NULL_TREE;
     }
+  else if (TREE_CODE (arg) == SSA_NAME)
+    {
+      gimple *stmt = SSA_NAME_DEF_STMT (arg);
+      if (!is_gimple_assign (stmt))
+	return NULL_TREE;
+
+      tree rhs1 = gimple_assign_rhs1 (stmt);
+      tree_code code = gimple_assign_rhs_code (stmt);
+      if (code == ADDR_EXPR)
+	return string_constant (rhs1, ptr_offset, mem_size, decl);
+      else if (code != POINTER_PLUS_EXPR)
+	return NULL_TREE;
+
+      tree offset;
+      if (tree str = string_constant (rhs1, &offset, mem_size, decl))
+	{
+	  /* Avoid pointers to arrays (see bug 86622).  */
+	  if (POINTER_TYPE_P (TREE_TYPE (rhs1))
+	      && TREE_CODE (TREE_TYPE (TREE_TYPE (rhs1))) == ARRAY_TYPE
+	      && !(decl && !*decl)
+	      && !(decl && tree_fits_uhwi_p (DECL_SIZE_UNIT (*decl))
+		   && mem_size && tree_fits_uhwi_p (*mem_size)
+		   && tree_int_cst_equal (*mem_size, DECL_SIZE_UNIT (*decl))))
+	    return NULL_TREE;
+
+	  tree rhs2 = gimple_assign_rhs2 (stmt);
+	  tree type = TREE_TYPE (rhs2);
+	  *ptr_offset = fold_build2 (PLUS_EXPR, type, offset, rhs2);
+	  return str;
+	}
+      return NULL_TREE;
+    }
   else if (DECL_P (arg))
     array = arg;
   else

gcc/testsuite/ChangeLog

+2018-09-25  Jeff Law  <law@redhat.com>
+
+	* gcc.dg/warn-stpcpy-no-nul.c: Drop unnecessary xfails.
+	* gcc.dg/warn-stplen-no-nul.c: Likewise.
+
 2018-09-25  Alexandre Oliva <oliva@adacore.com>
 
 	* gnat.dg/dinst.adb: Adjust for locviews.

gcc/testsuite/gcc.dg/warn-stpcpy-no-nul.c

@@ -71,13 +71,13 @@ void test_two_dim_array (char *d)
   T (&b[3][1] + 1);     /* { dg-warning "nul" }  */
   T (&b[3][v0]);        /* { dg-warning "nul" }  */
   T (&b[3][1] + v0);    /* { dg-warning "nul" }  */
-  T (&b[3][v0] + v1);   /* { dg-warning "nul" "bug ???" { xfail *-*-* } }  */
+  T (&b[3][v0] + v1);   /* { dg-warning "nul" }  */
 
   T (&b[i3][i1]);       /* { dg-warning "nul" }  */
   T (&b[i3][i1] + i1);  /* { dg-warning "nul" }  */
   T (&b[i3][v0]);       /* { dg-warning "nul" }  */
   T (&b[i3][i1] + v0);  /* { dg-warning "nul" }  */
-  T (&b[i3][v0] + v1);  /* { dg-warning "nul" "bug ???" { xfail *-*-* } }  */
+  T (&b[i3][v0] + v1);  /* { dg-warning "nul" }  */
 
   T (v0 ? "" : b[0]);
   T (v0 ? "" : b[1]);

gcc/testsuite/gcc.dg/warn-strlen-no-nul.c

@@ -71,9 +71,9 @@ T (&b[3][v0] + v1);     /* { dg-warning "nul" }  */
 T (&b[i3][i1]);         /* { dg-warning "nul" }  */
 T (&b[i3][i1] + 1);     /* { dg-warning "nul" }  */
 T (&b[i3][i1] + i1);    /* { dg-warning "nul" }  */
-T (&b[i3][v0]);         /* { dg-warning "nul" "pr86919" { xfail *-*-* } }  */
-T (&b[i3][i1] + v0);    /* { dg-warning "nul" "pr86919" { xfail *-*-* } }  */
-T (&b[i3][v0] + v1);    /* { dg-warning "nul" "pr86919" { xfail *-*-* } }  */
+T (&b[i3][v0]);         /* { dg-warning "nul" }  */
+T (&b[i3][i1] + v0);    /* { dg-warning "nul" }  */
+T (&b[i3][v0] + v1);    /* { dg-warning "nul" }  */
 
 T (v0 ? "" : b[0]);
 T (v0 ? "" : b[1]);
@@ -152,10 +152,10 @@ T (&s.b[1] + v0);     /* { dg-warning "nul" }  */
 
 T (&s.b[i0]);         /* { dg-warning "nul" }  */
 T (&s.b[i0] + i1);    /* { dg-warning "nul" }  */
-T (&s.b[i0] + v0);    /* { dg-warning "nul" "pr86919" { xfail *-*-* } }  */
+T (&s.b[i0] + v0);    /* { dg-warning "nul" }  */
 T (&s.b[i1]);         /* { dg-warning "nul" }  */
 T (&s.b[i1] + i1);    /* { dg-warning "nul" }  */
-T (&s.b[i1] + v0);    /* { dg-warning "nul" "pr86919" { xfail *-*-* } }  */
+T (&s.b[i1] + v0);    /* { dg-warning "nul" }  */
 
 struct B { struct A a[2]; };