Document -fgraphite-identity.

2009-07-30  Sebastian Pop  <sebastian.pop@amd.com>

	* doc/invoke.texi (-fgraphite-identity): Documented.

From-SVN: r150291

gcc/ChangeLog

 2009-07-30  Sebastian Pop  <sebastian.pop@amd.com>
 
+	* doc/invoke.texi (-fgraphite-identity): Documented.
+
+2009-07-30  Sebastian Pop  <sebastian.pop@amd.com>
+
 	* tree-scalar-evolution.c: Fix comment.
 	(instantiate_scev_1): Return unknow from scev instantiation if the
 	result is not above instantiate_below.

gcc/doc/invoke.texi

@@ -346,7 +346,7 @@ Objective-C and Objective-C++ Dialects}.
 -fira-region=@var{region} -fira-coalesce -fno-ira-share-save-slots @gol
 -fno-ira-share-spill-slots -fira-verbose=@var{n} @gol
 -fivopts -fkeep-inline-functions -fkeep-static-consts @gol
--floop-block -floop-interchange -floop-strip-mine @gol
+-floop-block -floop-interchange -floop-strip-mine -fgraphite-identity @gol
 -fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
 -fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
 -fmudflapir -fmudflapth -fno-branch-count-reg -fno-default-inline @gol
@@ -6592,6 +6592,15 @@ code transformation, GCC has to be configured with @option{--with-ppl}
 and @option{--with-cloog} to enable the Graphite loop transformation
 infrastructure.
 
+@item -fgraphite-identity
+@opindex fgraphite-identity
+Enable the identity transformation for graphite.  For every SCoP we generate
+the polyhedral representation and transform it back to gimple.  Using
+@option{-fgraphite-identity} we can check the costs or benefits of the
+GIMPLE -> GRAPHITE -> GIMPLE transformation.  Some minimal optimizations
+are also performed by the code generator CLooG, like index splitting and
+dead code elimination in loops.
+
 @item -fcheck-data-deps
 @opindex fcheck-data-deps
 Compare the results of several data dependence analyzers.  This option