[Bug tree-optimization/72787] New: Query related to gcc-4_6-branch fix for Bug-49279 (Getting issue with __restrict type qualifier)

[ranjan.winner at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72787

            Bug ID: 72787
           Summary: Query related to  gcc-4_6-branch  fix for Bug-49279
                    (Getting issue with __restrict type qualifier)
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ranjan.winner at gmail dot com
  Target Milestone: ---

Created attachment 39051
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39051&action=edit
Test Case

Question : Why for gcc-4.6 changes with tree-ssa.c file are omitted, I am
facing  problem due to this omission.

Link:- https://gcc.gnu.org/ml/gcc-patches/2011-10/msg00468.html

Below is the link of patch submitted for gcc-4.7 branch
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=2453d677b3879f218c98812c82c2ca1b2494f694

While below is link for gcc-4.6 branch:
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=479c60cd6e28540b9af9e0c436921ef23492a06a


Getting issue with gcc-4.6.3 version relating to __restrict qualifier.

While the issue is getting fix for gcc-4.8.1, the patch for both branches are
same, except for gcc-4_6-branch where change in file "gcc/tree-ssa.c" is not
considered as:
                   /* Do not lose casts to restrict qualified pointers.  */
                    -  if ((TYPE_RESTRICT (outer_type)
                    -      != TYPE_RESTRICT (inner_type))
                    -      && TYPE_RESTRICT (outer_type))
                    -  return false;

But if we consider this change then issue is getting resolve with gcc-4.6.3

1) FOR GCC-4.6.3

$ ./x86_64-ran-linux-gcc --version
x86_64-ran-linux-gcc (GCC) 4.6.3

$ ./x86_64-ran-linux-gcc -Wall -O2 -g test_restrict.c -o test_restrict
$ ./test_restrict.c
Case 1: dst size (100) is less than len (12800) //Incorrect Result 
Dest size is 12800 and len is 12800.

2) FOR GCC-4.8.1

$ ./x86_64-ran-linux-gcc --version
x86_64-windriver-linux-gcc (GCC) 4.8.1

$ ./x86_64-ran-linux-gcc -Wall -O2 -g test_restrict.c -o test_restrict
$ ./test_restrict
Case 2: dst size (12800) is equal to or greater than len (12800) //Incorrect
Result 
Dest size is 12800 and len is 12800.

-----------------TESTCASE-------------

#include <stdio.h> 
#include <string.h> 
#include <stdlib.h> 

#define DIMENSION_1 128 
#define DIMENSION_2 100 

char a[DIMENSION_1][DIMENSION_2]; 

char b[DIMENSION_1][DIMENSION_2]; 

extern inline __attribute__ ((always_inline)) int 
my_memcpy(void *__restrict dst, const void *__restrict src, size_t len) 
{ 
  size_t _sz = __builtin_object_size(dst, 1); 
  return (((_sz != (size_t) -1) && (_sz != 0)) 
      ? ((_sz < len) 
         ? printf("Case 1: dst size (%zu) is less than len (%zu)\n", _sz, len) 
         : printf("Case 2: dst size (%zu) is equal to or greater than len
(%zu)\n", _sz, len)) 
      : printf("Case 3: dst size is (%zu) and len is (%zu)\n", _sz, len)); 
} 

int main(int argc, char **argv) 
{ 
  my_memcpy(&a, &b, (DIMENSION_1*DIMENSION_2)); 

  printf("Dest size is %zu and len is %u.\n", 
     __builtin_object_size(&a, 1), DIMENSION_1*DIMENSION_2); 

  return 0; 
}