tree-ssa-loop-im.c: New file.

	* tree-ssa-loop-im.c: New file.
	* Makefile.in (tree-ssa-loop-im.o): Add.
	* cfgloop.c (superloop_at_depth): New function.
	* cfgloop.h (superloop_at_depth): Declare.
	* common.opt (ftree-lim): New flag.
	* expr.c (array_ref_up_bound): New function.
	* params.def (PARAM_LIM_EXPENSIVE): New parameter.
	* timevar.def (TV_LIM): New timevar.
	* tree-dfa.c (compute_immediate_uses): Respect TDFA_USE flags when
	computing immediate uses of a phi node.
	* tree-flow.h (struct tree_ann_common_d): Add aux field.
	(loop_commit_inserts, for_each_index, tree_ssa_lim): Declare.
	* tree-optimize.c (init_tree_optimization_passes): Add pass_lim.
	* tree-pass.h (pass_lim): Declare.
	* tree-ssa-loop.c (tree_ssa_loop_im, gate_tree_ssa_loop_im): New
	functions.
	(pass_lim): New pass structure.
	* tree-eh.c (tree_could_trap_p): Handle ARRAY_REFs correctly.
	* tree.c (in_array_bounds_p): New function.
	* tree.h (TREE_THIS_NOTRAP): Define also for ARRAY_REFs.
	(in_array_bounds_p, array_ref_up_bound): Declare.
	* doc/invoke.texi (-ftree-lim, --param lim-expensive): Document.
	* doc/passes.texi (tree-ssa-loop-im.c): Document.

From-SVN: r84441

1 files changed, 14 insertions, 3 deletions

diff --git a/gcc/doc/passes.texi b/gcc/doc/passes.texi
index 94b9ae5..9867e732 100644
--- a/gcc/doc/passes.texi
+++ b/gcc/doc/passes.texi
@@ -363,9 +363,20 @@ and is described by @code{pass_pre}.
 
 @item Loop optimization
 
-TODO: Presumably we're going to do something with loops here.  At
-present we don't, and this is a placeholder.  The pass is located
-in @file{tree-ssa-loop.c} and is described by @code{pass_loop}.
+The main driver of the pass is placed in @file{tree-ssa-loop.c}
+and described by @code{pass_loop}.
+
+The optimizations performed by this pass are:
+
+Loop invariant motion.  This pass moves only invariants that
+would be hard to handle on rtl level (function calls, operations that expand to
+nontrivial sequences of insns).  With @option{-funswitch-loops} it also moves
+operands of conditions that are invariant out of the loop, so that we can use
+just trivial invariantness analysis in loop unswitching.  The pass also includes
+store motion.  The pass is implemented in @file{tree-ssa-loop-im.c}.
+
+The optimizations also use various utility functions contained in
+@file{cfgloop.c}, @file{cfgloopanal.c} and @file{cfgloopmanip.c}.
 
 @item Conditional constant propagation