invoke.texi: Added descriptions of the scheduling heuristics that are enabled/disabled by...

2009-07-14  Ghassan Shobaki  <ghassan.shobaki@amd.com>
	
	* doc/invoke.texi: Added descriptions of the 
	scheduling heuristics that are enabled/disabled 
        by the flags introduced by a previous patch.

From-SVN: r149650

1 files changed, 29 insertions, 19 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index cff2431..a18da59 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -6235,46 +6235,56 @@ This only makes sense when scheduling after register allocation, i.e.@: with
 
 @item -fsched-group-heuristic
 @opindex fsched-group-heuristic
-Enable the group heuristic in the scheduler.  This is enabled by default
-when scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
+Enable the group heuristic in the scheduler.  This heuristic favors 
+the instruction that belongs to a schedule group.  This is enabled 
+by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
 or @option{-fschedule-insns2} or at @option{-O2} or higher.
 
 @item -fsched-critical-path-heuristic
 @opindex fsched-critical-path-heuristic
-Enable the critical-path heuristic in the scheduler.  This is enabled 
-by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
+Enable the critical-path heuristic in the scheduler.  This heuristic favors 
+instructions on the critical path.  This is enabled by default when 
+scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
 or @option{-fschedule-insns2} or at @option{-O2} or higher.
 
 @item -fsched-spec-insn-heuristic
 @opindex fsched-spec-insn-heuristic
-Enable the speculative instruction heuristic in the scheduler.  This is 
-enabled by default when scheduling is enabled, i.e.@: with 
-@option{-fschedule-insns} or @option{-fschedule-insns2} or 
-at @option{-O2} or higher.
+Enable the speculative instruction heuristic in the scheduler.  This 
+heuristic favors speculative instructions with greater dependency weakness.  
+This is enabled by default when scheduling is enabled, i.e.@: 
+with @option{-fschedule-insns} or @option{-fschedule-insns2} 
+or at @option{-O2} or higher.
 
 @item -fsched-reg-pressure-heuristic
 @opindex fsched-reg-pressure-heuristic
-Enable the register pressure heuristic in the scheduler.  This only makes  
-sense when scheduling before register allocation, i.e.@: 
+Enable the register pressure heuristic in the scheduler.  This heuristic
+favors the instruction with smaller contribution to register pressure.  
+This only makes sense when scheduling before register allocation, i.e.@: 
 with @option{-fschedule-insns} or at @option{-O2} or higher.
 
 @item -fsched-rank-heuristic
 @opindex fsched-rank-heuristic
-Enable the rank heuristic in the scheduler.  This is enabled by default 
-when scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
-or @option{-fschedule-insns2} or at @option{-O2} or higher.
+Enable the rank heuristic in the scheduler.  This heuristic favors 
+the instruction belonging to a basic block with greater size or frequency.  
+This is enabled by default when scheduling is enabled, i.e.@: 
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or 
+at @option{-O2} or higher.
 
 @item -fsched-last-insn-heuristic
 @opindex fsched-last-insn-heuristic
-Enable the last-instruction heuristic in the scheduler.  This is enabled 
-by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
-or @option{-fschedule-insns2} or at @option{-O2} or higher.
+Enable the last-instruction heuristic in the scheduler.  This heuristic 
+favors the instruction that is less dependent on the last instruction
+scheduled.  This is enabled by default when scheduling is enabled, 
+i.e.@: with @option{-fschedule-insns} or @option{-fschedule-insns2} or 
+at @option{-O2} or higher.
 
 @item -fsched-dep-count-heuristic
 @opindex fsched-dep-count-heuristic
-Enable the dependent-count heuristic in the scheduler.  This is enabled 
-by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns} 
-or @option{-fschedule-insns2} or at @option{-O2} or higher.
+Enable the dependent-count heuristic in the scheduler.  This heuristic 
+favors the instruction that has more instructions depending on it.  
+This is enabled by default when scheduling is enabled, i.e.@: 
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or 
+at @option{-O2} or higher.
 
 @item -fsched2-use-traces
 @opindex fsched2-use-traces