PR rtl-optimization/20376

	* toplev.c (process_options): Enable -fweb and -frename-registers when
	unrolling.
	* doc/invoke.texi: Update the information about when -fweb and
	-frename-registers are enabled.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@101961 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 7 insertions, 9 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 0f509d0ce7b..ba355c0d046 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -5017,8 +5017,7 @@ the loop is entered.  This usually makes programs run more slowly.
 @opindex -fsplit-ivs-in-unroller
 Enables expressing of values of induction variables in later iterations
 of the unrolled loop using the value in the first iteration.  This breaks
-long dependency chains, thus improving efficiency of the scheduling passes
-(for best results, @option{-fweb} should be used as well).
+long dependency chains, thus improving efficiency of the scheduling passes.
 
 Combination of @option{-fweb} and CSE is often sufficient to obtain the
 same effect.  However in cases the loop body is more complicated than
@@ -5260,9 +5259,7 @@ passes, such as CSE, loop optimizer and trivial dead code remover.  It can,
 however, make debugging impossible, since variables will no longer stay in a
 ``home register''.
 
-Enabled at levels @option{-O2}, @option{-O3}, @option{-Os},
-on targets where the default format for debugging information supports
-variable tracking.
+Enabled by default with @option{-funroll-loops}.
 
 @item -fwhole-program
 @opindex fwhole-program
@@ -5524,7 +5521,7 @@ debug information format adopted by the target, however, it can
 make debugging impossible, since variables will no longer stay in
 a ``home register''.
 
-Not enabled by default at any level because it has known bugs.
+Enabled by default with @option{-funroll-loops}.
 
 @item -ftracer
 @opindex ftracer
@@ -5538,9 +5535,10 @@ Enabled with @option{-fprofile-use}.
 @opindex funroll-loops
 Unroll loops whose number of iterations can be determined at compile time or
 upon entry to the loop.  @option{-funroll-loops} implies
-@option{-frerun-cse-after-loop}.  It also turns on complete loop peeling
-(i.e.@: complete removal of loops with small constant number of iterations).
-This option makes code larger, and may or may not make it run faster.
+@option{-frerun-cse-after-loop}, @option{-fweb} and @option{-frename-registers}. 
+It also turns on complete loop peeling (i.e.@: complete removal of loops with
+small constant number of iterations).  This option makes code larger, and may
+or may not make it run faster.
 
 Enabled with @option{-fprofile-use}.