Frontend pass assumptions

[pocmatos at gmail dot com (Paulo J. Matos)]

Hello,

I am working on the new pass (previously discussed), to optimise switch
cases.

I am almost finishing it, however, for practical reasons I am
implementing it first over GCC4.3 and once tested, will port it to svn
trunk and post it on gcc-patches.

There are something that are still not working. Mainly the issue is that
GCC doesn't really accept the code I generate during the patch. 

Some issues:

1. To generate a conditional (like if(...){} else {}) I am using a
COND_EXPR;
2. And when I have a complex condition I generate a TRUTH_ANDIF_EXPR and
then corresponding LE_EXPR, or LT_EXPR, etc.
3. To iterate through the tree I am using a tree_stmt_iterator. And
using tsi_delink to remove stmts from the tree and tsi_link_before/after
to add stmts to the tree.

After my pass is run I get:
,----
| switch_compact.c: In function 'g':
| switch_compact.c:7: error: bb_for_stmt (stmt) is set to a wrong basic
| block
| switch_compact.c:7: error: invalid conditional operand
| 8 <= n_1(D) && n_1(D) <= 17;
| 
| switch_compact.c:7: internal compiler error: verify_stmts failed
`----

Could you please comment on the above issues so I can try to track down
the problem?

PS. Note that the reason why I am not posting the patch is simply
because I assume you only look at patches for gcc-trunk. However, if you
don't mind taking a look at a pass for GCC4.3 at this point, do let me
know and I will post it (either here on in gcc-patches).

Cheers,

-- 
PMatos