[PATCH GCC]Consider NOP_EXPR and CONVERT_EXPR as equal nodes in operand_equal_p

[Bin Cheng]

Hi,
This is a case of NOP_EXPR and CONVERT_EXPR not compared equal in
operand_equal_p, resulting in below two nodes are considered different:

NODE 0:
<convert_expr 0xb72ddb04
    type <integer_type 0xb74602a0 short int sizes-gimplified public HI
        size <integer_cst 0xb744e7c4 constant 16>
        unit size <integer_cst 0xb744e7e0 constant 2>
        align 16 symtab 0 alias set 4 canonical type 0xb74602a0
precision 16 min <integer_cst 0xb744e770 -32768> max <integer_cst
0xb744e78c 32767> context <translation_unit_decl 0xb760dd80 D.6120>
        pointer_to_this <pointer_type 0xb7241600>>

    arg 0 <ssa_name 0xb72882f8
        type <integer_type 0xb7460420 long int sizes-gimplified public SI
            size <integer_cst 0xb744e55c constant 32>
            unit size <integer_cst 0xb744e578 constant 4>
            align 32 symtab 0 alias set 5 canonical type 0xb7460420
precision 32 min <integer_cst 0xb744e888 -2147483648> max <integer_cst
0xb744e8a4 2147483647> context <translation_unit_decl 0xb760dd80
D.6120>
            pointer_to_this <pointer_type 0xb74677e0>>
        visiteddef_stmt _23 = *_22;

        version 23>>

NODE 1:
<nop_expr 0xb72e1b54
    type <integer_type 0xb74602a0 short int sizes-gimplified public HI
        size <integer_cst 0xb744e7c4 constant 16>
        unit size <integer_cst 0xb744e7e0 constant 2>
        align 16 symtab 0 alias set 4 canonical type 0xb74602a0
precision 16 min <integer_cst 0xb744e770 -32768> max <integer_cst
0xb744e78c 32767> context <translation_unit_decl 0xb760dd80 D.6120>
        pointer_to_this <pointer_type 0xb7241600>>

    arg 0 <ssa_name 0xb72882f8
        type <integer_type 0xb7460420 long int sizes-gimplified public SI
            size <integer_cst 0xb744e55c constant 32>
            unit size <integer_cst 0xb744e578 constant 4>
            align 32 symtab 0 alias set 5 canonical type 0xb7460420
precision 32 min <integer_cst 0xb744e888 -2147483648> max <integer_cst
0xb744e8a4 2147483647> context <translation_unit_decl 0xb760dd80
D.6120>
            pointer_to_this <pointer_type 0xb74677e0>>
        visiteddef_stmt _23 = *_22;

        version 23>>


This patch fixes the problem. Please refer to
http://gcc.gnu.org/ml/gcc/2013-05/msg00199.html for more information.

Bootstrap and test on x86 and cortex-a15.  Is it OK?

Thanks.
bin

2013-06-13  Bin Cheng  <bin.ch...@arm.com>

        * fold-const.c (operand_equal_p): Consider NOP_EXPR and CONVERT_EXPR
        as equal nodes.

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 199844)
+++ gcc/fold-const.c    (working copy)
@@ -2473,9 +2473,13 @@ operand_equal_p (const_tree arg0, const_tree arg1,
     }
 
   if (TREE_CODE (arg0) != TREE_CODE (arg1)
-      /* This is needed for conversions and for COMPONENT_REF.
-        Might as well play it safe and always test this.  */
-      || TREE_CODE (TREE_TYPE (arg0)) == ERROR_MARK
+      /* NOP_EXPR and CONVERT_EXPR are considered equal.  */
+      && !(CONVERT_EXPR_P (arg0) && CONVERT_EXPR_P (arg1)))
+    return 0;
+
+  /* This is needed for conversions and for COMPONENT_REF.
+     Might as well play it safe and always test this.  */
+  if (TREE_CODE (TREE_TYPE (arg0)) == ERROR_MARK
       || TREE_CODE (TREE_TYPE (arg1)) == ERROR_MARK
       || TYPE_MODE (TREE_TYPE (arg0)) != TYPE_MODE (TREE_TYPE (arg1)))
     return 0;