Bug 15878

Summary:	a & b & ~a & ~b not optimized at the tree level
Product:	gcc	Reporter:	Andrew Pinski <pinskia>
Component:	tree-optimization	Assignee:	Daniel Berlin <dberlin>
Status:	RESOLVED FIXED
Severity:	enhancement	CC:	gcc-bugs
Priority:	P2	Keywords:	missed-optimization, TREE
Version:	4.0.0
Target Milestone:	4.2.0
See Also:	https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111543
Host:		Target:
Build:		Known to work:
Known to fail:		Last reconfirmed:	2005-12-09 04:24:20
Bug Depends on:	21445
Bug Blocks:	19986

Description Andrew Pinski 2004-06-08 18:36:45 UTC

From looking at bugs which were fixed for 3.5.0 which were done on the RTL, I noticed this one (From 
PR 5263).

int f(int a,int b) { return a&b~a&~b; }

Comment 1 Andrew Pinski 2004-06-20 20:38:20 UTC

Confirmed.

Comment 2 Daniel Berlin 2005-08-28 20:00:06 UTC

I have a patch for this

Comment 3 Andrew Pinski 2005-12-13 04:18:57 UTC

Fixed by:
2005-12-12  Jeff Law  <law@redhat.com>

        * tree-ssa-dom.c (simplify_rhs_and_lookup_avail_expr): Remove
        reassociation code.
        * passes.c (init_optimization_passes): Run reassociation again
        after loop optimizations.

2005-12-12  Daniel Berlin  <dberlin@dberlin.org>

        * tree-ssa-dom.c (thread_across_edge): Canonicalize condition
        if necessary.
        (optimize_stmt): Ditto.
        (canonicalize_comparison): New function.
        * tree-ssa-operands.c (swap_tree_operands): Make external.
        (get_expr_operands): Stop auto-canonicalization.
        * tree-ssa-reassoc.c: Rewrite.
        (init_optimization_passes):
        * tree-flow.h (swap_tree_operands): Prototype.
        * Makefile.in (tree-ssa-reassoc.o): Update dependencies.