common.opt (ftree-fre): New flag.

	* common.opt (ftree-fre): New flag.
	* flags.h (flag_tree_fre): Declare.
	* opts.c (decode_options): Set.
	* timevar.def (TV_TREE_FRE): Define.
	* tree-flow-inline.h (may_propagate_copy): Re-arrange for
	readability.  Handle destinations that are not SSA_NAMEs.
	* tree-flow.h (struct ptr_info_def): Move from tree.h
	(cprop_into_stmt, cprop_into_successor_phis): Remove.
	(vn_compute, vn_lookup_or_add, vn_add, vn_lookup): Add
	vuse_optype parameter.
	* tree-pass.h (pass_fre): Declare.
	* tree-ssa-copy.c (cprop_operand): Move to tree-ssa-dom.c
	(cprop_into_stmt): Likewise.
	(cprop_into_successor_phis): Likewise.
	* tree-ssa-dom.c (eliminate_redundant_computations): Fix
	argument ordering in call to may_propagate_copy.
	* tree-ssa-pre.c (is_undefined_value): Assume hard registers
	to be always defined.
	(add_to_sets): New local function.
	(create_value_expr_from): New local function.
	(compute_avail): Call them.
	(eliminate): Don't ignore statements with virtual operands.
	(init_pre): New local function.
	(fini_pre): New local function.
	(execute_pre): Call them.
	Add argument DO_FRE.  Don't do insertion if DO_FRE is true.
	(do_pre): New function.
	(do_fre): New function.
	(gate_fre): New function.
	(pass_fre): Declare.
	* tree-ssa.c (init_tree_ssa): Don't call vn_init.
	(delete_tree_ssa): Don't call vn_delete.
	* tree-vn.c (val_expr_pair_d): Add documentation.
	(vn_compute): Add VUSES argument to incorporate in computing
	hash values.  Update all callers.
	(expressions_equal_p): Call operand_equal_p with
	OEP_PURE_SAME.
	(vn_add): Add VUSES argument.  Update all callers.
	(vn_lookup): Likewise.
	(vn_lookup_or_add): Likewise.
	* doc/invoke.texi: Document -ftree-fre and -fdump-tree-fre.

From-SVN: r83837

1 files changed, 14 insertions, 1 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 1d70843..510eda9 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -262,6 +262,7 @@ in the following sections.
 -fdump-tree-copyrename@r{[}-@var{n}@r{]} @gol
 -fdump-tree-nrv @gol
 -fdump-tree-sra@r{[}-@var{n}@r{]} @gol
+-fdump-tree-fre@r{[}-@var{n}@r{]} @gol
 -feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
 -feliminate-unused-debug-symbols -fmem-report -fprofile-arcs -ftree-based-profiling @gol
 -frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
@@ -313,7 +314,7 @@ in the following sections.
 -funswitch-loops  -fold-unroll-loops  -fold-unroll-all-loops @gol
 -ftree-pre  -ftree-ccp  -ftree-dce  @gol
 -ftree-dominator-opts -ftree-dse -ftree-copyrename @gol
--ftree-ch -ftree-sra -ftree-ter -ftree-lrs @gol
+-ftree-ch -ftree-sra -ftree-ter -ftree-lrs -ftree-fre @gol
 --param @var{name}=@var{value}
 -O  -O0  -O1  -O2  -O3  -Os}
 
@@ -3553,6 +3554,11 @@ Dump each function after CCP.  The file name is made by appending
 Dump trees after partial redundancy elimination.  The file name is made
 by appending @file{.pre} to the source file name.
 
+@item fre
+@opindex fdump-tree-fre
+Dump trees after full redundancy elimination.  The file name is made
+by appending @file{.fre} to the source file name.
+
 @item dce
 @opindex fdump-tree-dce
 Dump each function after dead code elimination.  The file name is made by
@@ -4369,6 +4375,13 @@ Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
 Perform Partial Redundancy Elimination (PRE) on trees.  This flag is
 enabled by default at -O and higher.
 
+@item -ftree-fre
+Perform Full Redundancy Elimination (FRE) on trees.  The difference
+between FRE and PRE is that FRE only considers expressions
+that are computed on all paths leading to the redundant computation.
+This analysis faster than PRE, though it exposes fewer redundancies.
+This flag is enabled by default at -O and higher.
+
 @item -ftree-ccp
 Perform sparse conditional constant propagation (CCP) on trees.  This flag
 is enabled by default at -O and higher.