Re: gcc 4.5.1 / as 2.20.51.0.11 miscompiling drivers/char/i8k.c ?

[Jakub Jelinek]

On Mon, Nov 15, 2010 at 07:58:48PM +0100, Jakub Jelinek wrote:
> Now, not sure why this happens, as there is
>     case GIMPLE_ASM:
>       for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
>         {
>           tree op = gimple_asm_clobber_op (stmt, i);
>           if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 
> 1)
>             {
>               if (dump_file)
>                 fprintf (dump_file, "    memory asm clobber is not 
> const/pure");
>               /* Abandon all hope, ye who enter here. */
>               local->pure_const_state = IPA_NEITHER;
>             }
>         }
> Debugging...

Ah, the problem is that memory_identifier_string is only initialized in
ipa-reference.c's initialization, so it can be (and is in this case) NULL in
ipa-pure-const.c.

Two possible fixes (the latter is apparently what is used in
tree-ssa-operands.c, so is probably sufficient).  Guess ipa-reference.c
should be changed to do the same and just drop memory_identifier_string.

        Jakub

--- gcc/ipa-pure-const.c.jj     2010-08-11 16:06:19.000000000 +0200
+++ gcc/ipa-pure-const.c        2010-11-15 20:06:36.121310614 +0100
@@ -460,7 +460,10 @@ check_stmt (gimple_stmt_iterator *gsip, 
       for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
        {
          tree op = gimple_asm_clobber_op (stmt, i);
-         if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1)
+         if (TREE_CODE (TREE_VALUE (op)) == STRING_CST
+             && TREE_STRING_LENGTH (TREE_VALUE (op)) == sizeof ("memory")
+             && memcmp (TREE_STRING_POINTER (TREE_VALUE (op)), "memory",
+                        sizeof ("memory")) == 0)
            {
               if (dump_file)
                 fprintf (dump_file, "    memory asm clobber is not 
const/pure");

--- gcc/ipa-pure-const.c.jj     2010-08-11 16:06:19.000000000 +0200
+++ gcc/ipa-pure-const.c        2010-11-15 20:07:51.463716989 +0100
@@ -460,7 +460,7 @@ check_stmt (gimple_stmt_iterator *gsip, 
       for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
        {
          tree op = gimple_asm_clobber_op (stmt, i);
-         if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1)
+         if (strcmp (TREE_STRING_POINTER (TREE_VALUE (link)), "memory") == 0)
            {
               if (dump_file)
                 fprintf (dump_file, "    memory asm clobber is not 
const/pure");