[Bug c/21024] New: Type mismatch in a comparison.

[Bug c/21024] New: Type mismatch in a comparison.

[kazu at cs dot umass dot edu]

Consider:

extern void *bar (void);

int
foo (unsigned int *p)
{
  const void *r = bar ();

  if (r >= (const void *) *p)
    return 1;

  return 0;
}

t03.generic looks like so.

foo (p)
{
  void * D.1155;
  unsigned int D.1156;
  int D.1157;
  const void * r;

  D.1155 = bar ();
  r = D.1155;
  D.1156 = *p;
  if (D.1156 <= r)
    {
      D.1157 = 1;
      return D.1157;
    }
  else
    {
      
    }
  D.1157 = 0;
  return D.1157;
}

Note that "if (D.1156 <= r)" has a type mismatch, namely an integer type
v.s. a pointer type.

This PR is the real cause of PR 21021.

-- 
           Summary: Type mismatch in a comparison.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kazu at cs dot umass dot edu
                CC: dnovillo at redhat dot com,gcc-bugs at gcc dot gnu dot
                    org
OtherBugsDependingO 21021
             nThis:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024

[Bug c/21024] Type mismatch in a comparison.

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-14 16:48 -------
Confirmed.  This has been wrong since "3.5.0 20040909".

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-04-14 16:48:13
               date|                            |
            Version|unknown                     |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024

[Bug c/21024] fold generates a comparison of two operands whose types do not match

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2005-04-15 16:37 -------
build_binary_op builds a binary tree node for r >= (const void *) *q;
Here are the details.

(gdb) p resultcode
$2 = GE_EXPR
(gdb) call debug_tree(build_type)
 <integer_type 0xb7cf5510 int public SI
    size <integer_cst 0xb7ced408 type <integer_type 0xb7cf5288 bit_size_type>
constant invariant 32>
    unit size <integer_cst 0xb7ced198 type <integer_type 0xb7cf521c unsigned
int> constant invariant 4>
    align 32 symtab 0 alias set -1 precision 32 min <integer_cst 0xb7ced3c0
-2147483648> max <integer_cst 0xb7ced3d8 2147483647>
    pointer_to_this <pointer_type 0xb7d029b4>>
(gdb) call debug_tree(op0)
 <var_decl 0xb7d6a288 r
    type <pointer_type 0xb7d6a21c
        type <void_type 0xb7d6a1b0 void readonly VOID
            align 8 symtab 0 alias set -1
            pointer_to_this <pointer_type 0xb7d6a21c>>
        unsigned SI
        size <integer_cst 0xb7ced408 constant invariant 32>
        unit size <integer_cst 0xb7ced198 constant invariant 4>
        align 32 symtab 0 alias set -1>
    used unsigned SI file test.c line 6 size <integer_cst 0xb7ced408 32> unit
size <integer_cst 0xb7ced198 4>
    align 32 context <function_decl 0xb7d6a06c foo> initial <nop_expr 0xb7cf22c0>>
(gdb) call debug_tree(op1)
 <convert_expr 0xb7cf2320
    type <pointer_type 0xb7d6a21c
        type <void_type 0xb7d6a1b0 void readonly VOID
            align 8 symtab 0 alias set -1
            pointer_to_this <pointer_type 0xb7d6a21c>>
        unsigned SI
        size <integer_cst 0xb7ced408 constant invariant 32>
        unit size <integer_cst 0xb7ced198 constant invariant 4>
        align 32 symtab 0 alias set -1>
   
    arg 0 <indirect_ref 0xb7cf2300
        type <integer_type 0xb7cf557c unsigned int public unsigned SI size
<integer_cst 0xb7ced408 32> unit size <integer_cst 0xb7ced198 4>
            align 32 symtab 0 alias set -1 precision 32 min <integer_cst
0xb7ced480 0> max <integer_cst 0xb7ced468 4294967295>
            pointer_to_this <pointer_type 0xb7d63e58>>
       
        arg 0 <parm_decl 0xb7d63ec4 p type <pointer_type 0xb7d63e58>
            used unsigned SI file test.c line 4 size <integer_cst 0xb7ced408 32>
unit size <integer_cst 0xb7ced198 4>
            align 32 context <function_decl 0xb7d6a06c foo> result <pointer_type
0xb7d63e58> initial <pointer_type 0xb7d63e58> arg-type <pointer_type 0xb7d63e58>
arg-type-as-written <pointer_type 0xb7d63e58> chain <parm_decl 0xb7d63f30 q>>>>

Before the binary tree node is returned to the caller, build_binary_op
calls fold to fold the newly built tree node.  Since the tree node is
a binary one, fold calls fold_binary.  fold_binary strips what it
considers to be useless type conversion.  By the time we get to the
case handling GE_EXPR, we have the following operands whose types do
not match.

(gdb) call debug_tree(arg0)
 <var_decl 0xb7d6a288 r
    type <pointer_type 0xb7d6a21c
        type <void_type 0xb7d6a1b0 void readonly VOID
            align 8 symtab 0 alias set -1
            pointer_to_this <pointer_type 0xb7d6a21c>>
        unsigned SI
        size <integer_cst 0xb7ced408 constant invariant 32>
        unit size <integer_cst 0xb7ced198 constant invariant 4>
        align 32 symtab 0 alias set -1>
    used unsigned SI file test.c line 6 size <integer_cst 0xb7ced408 32> unit
size <integer_cst 0xb7ced198 4>
    align 32 context <function_decl 0xb7d6a06c foo> initial <nop_expr 0xb7cf22c0>>
(gdb) call debug_tree(arg1)
 <indirect_ref 0xb7cf2300
    type <integer_type 0xb7cf557c unsigned int public unsigned SI
        size <integer_cst 0xb7ced408 constant invariant 32>
        unit size <integer_cst 0xb7ced198 constant invariant 4>
        align 32 symtab 0 alias set -1 precision 32 min <integer_cst 0xb7ced480
0> max <integer_cst 0xb7ced468 4294967295>
        pointer_to_this <pointer_type 0xb7d63e58>>
   
    arg 0 <parm_decl 0xb7d63ec4 p
        type <pointer_type 0xb7d63e58 type <integer_type 0xb7cf557c unsigned int>
            unsigned SI size <integer_cst 0xb7ced408 32> unit size <integer_cst
0xb7ced198 4>
            align 32 symtab 0 alias set -1>
        used unsigned SI file test.c line 4 size <integer_cst 0xb7ced408 32>
unit size <integer_cst 0xb7ced198 4>
        align 32 context <function_decl 0xb7d6a06c foo> result <pointer_type
0xb7d63e58> initial <pointer_type 0xb7d63e58> arg-type <pointer_type 0xb7d63e58>
arg-type-as-written <pointer_type 0xb7d63e58>
        chain <parm_decl 0xb7d63f30 q type <pointer_type 0xb7d63e58>
            unsigned SI file test.c line 4 size <integer_cst 0xb7ced408 32> unit
size <integer_cst 0xb7ced198 4>
            align 32 context <function_decl 0xb7d6a06c foo> result <pointer_type
0xb7d63e58> initial <pointer_type 0xb7d63e58> arg-type <pointer_type 0xb7d63e58>
arg-type-as-written <pointer_type 0xb7d63e58>>>>

Note that arg0 is of a pointer type, whereas arg1 is of an integer
type.

Roger, I don't think it's OK to create this kind of type mismatch.
At the very least, that would complicate SSA optimizers.  Thoughts?


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |roger at eyesopen dot com
            Summary|Type mismatch in a          |fold generates a comparison
                   |comparison.                 |of two operands whose types
                   |                            |do not match


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024

[Bug middle-end/21024] fold generates a comparison of two operands whose types do not match

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2005-04-16 14:07 -------
Patch posted:
http://gcc.gnu.org/ml/gcc-patches/2005-04/msg01830.html


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024

[Bug middle-end/21024] fold generates a comparison of two operands whose types do not match

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-04-17 01:38 -------
Subject: Bug 21024

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	kazu@gcc.gnu.org	2005-04-17 01:38:28

Modified files:
	gcc            : ChangeLog builtins.c fold-const.c 

Log message:
	PR middle-end/21024
	* builtins.c (expand_builtin_strcat): Convert the result of
	strlen to the right type.
	* fold-const.c (fold_binary) <PLUS_EXPR>: Use fold_convert to
	avoid creating type mismatches.
	<GE_EXPR>: Pass op0 and op1 to fold_build2 to avoid creating
	type mismatches.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.8326&r2=2.8327
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/builtins.c.diff?cvsroot=gcc&r1=1.455&r2=1.456
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/fold-const.c.diff?cvsroot=gcc&r1=1.561&r2=1.562



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024

[Bug middle-end/21024] fold generates a comparison of two operands whose types do not match

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2005-04-17 01:41 -------
Just checked in a patch.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024

[Bug middle-end/21024] fold generates a comparison of two operands whose types do not match

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21024