[PATCH] Pretty-printing of some unsupported expressions (PR c/35441)

[Volker Reichelt <v dot reichelt at netcologne dot de>]

The patch below addresses some pretty-printer issues. More precisely,
it handles 6 types of expressions that weren't handled before:

  a) EXACT_DIV_EXPR, RDIV_EXPR,
  b) LROTATE_EXPR, RROTATE_EXPR,
  c) MAX_EXPR, MIN_EXPR.

Right now we print for the testcase below:

  #'exact_div_expr' not supported by expression#'pr35441.c: In function 'foo1':
  pr35441.c:8:6: error: called object  is not a function or function pointer
  #'rdiv_expr' not supported by expression#'pr35441.c: In function 'foo2':
  pr35441.c:13:5: error: called object  is not a function or function pointer
  #'lrotate_expr' not supported by expression#'pr35441.c: In function 'foo3':
  pr35441.c:18:11: error: called object  is not a function or function pointer
  #'rrotate_expr' not supported by expression#'pr35441.c:19:11: error: called object  is not a function or function pointer
  #'min_expr' not supported by expression#'pr35441.c: In function 'foo4':
  pr35441.c:24:14: error: called object  is not a function or function pointer
  #'max_expr' not supported by expression#'pr35441.c:25:14: error: called object  is not a function or function pointer

With the patch we would print:

  pr35441.c: In function 'foo1':
  pr35441.c:8:6: error: called object '((long int)p - (long int)q) / 8' is not a function or function pointer
  pr35441.c: In function 'foo2':
  pr35441.c:13:5: error: called object 'x / y' is not a function or function pointer
  pr35441.c: In function 'foo3':
  pr35441.c:18:11: error: called object 'i << j' is not a function or function pointer
  pr35441.c:19:11: error: called object 'i >> j' is not a function or function pointer
  pr35441.c: In function 'foo4':
  pr35441.c:24:14: error: called object 'min(q,  p)' is not a function or function pointer
  pr35441.c:25:14: error: called object 'max(q,  p)' is not a function or function pointer


a) This part (with foo1 and foo2 from the testcase) is straightforward.

However, I'm not sure how to print the actual operators for the other
2 groups.

b) I chose the shift operators 'a << b' and 'a >> b' for the rotate
   expressions, which is not 100% correct. Would it be better to use
   something like 'lrotate(a, b)', '__lrotate__(a, b)' or 'a lrotate b'
   instead? Or is there something like an '__builtin_lrotate' that I misseed?

c) I chose 'max(q, b)' and 'min(q, b)'.
   Would something like '__max__(q, b)' be better?
   Trying to print the expression 'p < q ? p : q' from the testcase
   might be possible. But there are several different expressions like
   'p < q ? p : q', 'p > q ? q : p', 'p >= q ? q : p' and '!(p >= q) ? p : q'
   that are all converted into MIN_EXPR, so I would rather stay with
   and explicit 'min'/'max' instead.

In addition I found some more division operators in gcc/tree.def that
aren't handled by the pretty-printer:

  CEIL_DIV_EXPR
  FLOOR_DIV_EXPR
  ROUND_DIV_EXPR
  CEIL_MOD_EXPR
  FLOOR_MOD_EXPR
  ROUND_MOD_EXPR

Alas I don't have testcases for them. Nevertheless, I could handle them
like the other MOD and DIV operators just to be safe.

Any comments, or is the patch OK as is for trunk?
Bootstrapped and regtested on x86_64-linux.

Regards,
Volker


2017-03-09  Volker Reichelt  <v.reichelt@netcologne.de>

	PR c/35441
	* c-pretty-print.c (c_pretty_printer::expression): Handle MAX_EXPR,
	MIN_EXPR, EXACT_DIV_EXPR, RDIV_EXPR, LROTATE_EXPR, RROTATE_EXPR.
	(c_pretty_printer::postfix_expression): Handle MAX_EXPR, MIN_EXPR.
	(c_pretty_printer::multiplicative_expression): Handle EXACT_DIV_EXPR,
	RDIV_EXPR.
	(pp_c_shift_expression): Handle LROTATE_EXPR, RROTATE_EXPR.

Index: gcc/c-family/c-pretty-print.c
===================================================================
--- gcc/c-family/c-pretty-print.c	(revision 245962)
+++ gcc/c-family/c-pretty-print.c	(working copy)
@@ -1551,6 +1551,14 @@
 			   : "__builtin_islessgreater");
       goto two_args_fun;
 
+    case MAX_EXPR:
+      pp_c_ws_string (this, "max");
+      goto two_args_fun;
+
+    case MIN_EXPR:
+      pp_c_ws_string (this, "min");
+      goto two_args_fun;
+
     two_args_fun:
       pp_c_left_paren (this);
       expression (TREE_OPERAND (e, 0));
@@ -1829,6 +1837,8 @@
     case MULT_EXPR:
     case TRUNC_DIV_EXPR:
     case TRUNC_MOD_EXPR:
+    case EXACT_DIV_EXPR:
+    case RDIV_EXPR:
       multiplicative_expression (TREE_OPERAND (e, 0));
       pp_c_whitespace (this);
       if (code == MULT_EXPR)
@@ -1890,9 +1900,12 @@
     {
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
+    case LROTATE_EXPR:
+    case RROTATE_EXPR:
       pp_c_shift_expression (pp, TREE_OPERAND (e, 0));
       pp_c_whitespace (pp);
-      pp_string (pp, code == LSHIFT_EXPR ? "<<" : ">>");
+      pp_string (pp,
+		 code == LSHIFT_EXPR || code == LROTATE_EXPR ? "<<" : ">>");
       pp_c_whitespace (pp);
       pp_c_additive_expression (pp, TREE_OPERAND (e, 1));
       break;
@@ -2186,6 +2199,8 @@
     case UNLT_EXPR:
     case UNGE_EXPR:
     case UNGT_EXPR:
+    case MAX_EXPR:
+    case MIN_EXPR:
     case ABS_EXPR:
     case CONSTRUCTOR:
     case COMPOUND_LITERAL_EXPR:
@@ -2217,11 +2232,15 @@
     case MULT_EXPR:
     case TRUNC_MOD_EXPR:
     case TRUNC_DIV_EXPR:
+    case EXACT_DIV_EXPR:
+    case RDIV_EXPR:
       multiplicative_expression (e);
       break;
 
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
+    case LROTATE_EXPR:
+    case RROTATE_EXPR:
       pp_c_shift_expression (this, e);
       break;
 
2017-03-09  Volker Reichelt  <v.reichelt@netcologne.de>

	PR c/35441
	* gcc.dg/pr35441.c: New test.

Index: gcc/testsuite/gcc.dg/pr35441.c
===================================================================
--- gcc/testsuite/gcc.dg/pr35441.c	2017-03-08 18:38:39
+++ gcc/testsuite/gcc.dg/pr35441.c	2017-03-08 23:43:06
@@ -0,0 +1,26 @@
+/* PR c/35441 */
+/* { dg-do compile } */
+/* { dg-options "-fno-diagnostics-show-caret" } */
+/* { dg-bogus "not supported by" "" { target *-*-* } 0 } */
+
+void foo1(char **p, char **q)
+{
+  (p - q)();			/* { dg-error "is not a function" } */
+}
+
+void foo2(double x, double y)
+{
+  (x/y)();			/* { dg-error "is not a function" } */
+}
+
+void foo3(unsigned i, int j)
+{
+  (i << j | i >> (32 - j))();	/* { dg-error "is not a function" } */
+  (i >> j | i << (32 - j))();	/* { dg-error "is not a function" } */
+}
+
+void foo4(char *p, char *q)
+{
+  (p < q ? p : q)();		/* { dg-error "is not a function" } */
+  (p > q ? p : q)();		/* { dg-error "is not a function" } */
+}
===================================================================