Add the -ftree-loop-if-convert flag.

2010-07-08  Sebastian Pop  <sebastian.pop@amd.com>

	* common.opt (ftree-loop-if-convert): New flag.
	* doc/invoke.texi (ftree-loop-if-convert): Documented.
	* tree-if-conv.c (gate_tree_if_conversion): Enable if-conversion
	when flag_tree_loop_if_convert is set.

From-SVN: r161963

4 files changed, 26 insertions, 5 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7cdc860..d745186 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2010-07-08  Sebastian Pop  <sebastian.pop@amd.com>
+
+	* common.opt (ftree-loop-if-convert): New flag.
+	* doc/invoke.texi (ftree-loop-if-convert): Documented.
+	* tree-if-conv.c (gate_tree_if_conversion): Enable if-conversion
+	when flag_tree_loop_if_convert is set.
+
 2010-07-08  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.c: Use short syntax for function calls
diff --git a/gcc/common.opt b/gcc/common.opt
index 6ca787a..111d7b7 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -653,6 +653,10 @@ fif-conversion2
 Common Report Var(flag_if_conversion2) Optimization
 Perform conversion of conditional jumps to conditional execution
 
+ftree-loop-if-convert
+Common Report Var(flag_tree_loop_if_convert) Init(-1) Optimization
+Convert conditional jumps in innermost loops to branchless equivalents
+
 ; -finhibit-size-directive inhibits output of .size for ELF.
 ; This is used only for compiling crtstuff.c,
 ; and it may be extended to other effects
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index d70f130..4d6a1af 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -342,7 +342,7 @@ Objective-C and Objective-C++ Dialects}.
 -fearly-inlining -fipa-sra -fexpensive-optimizations -ffast-math @gol
 -ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
 -fforward-propagate -ffunction-sections @gol
--fgcse -fgcse-after-reload -fgcse-las -fgcse-lm @gol
+-fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity @gol
 -fgcse-sm -fif-conversion -fif-conversion2 -findirect-inlining @gol
 -finline-functions -finline-functions-called-once -finline-limit=@var{n} @gol
 -finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg -fipa-pta @gol
@@ -352,7 +352,7 @@ Objective-C and Objective-C++ Dialects}.
 -fira-loop-pressure -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 -fgraphite-identity @gol
+-floop-block -floop-interchange -floop-strip-mine @gol
 -floop-parallelize-all -flto -flto-compression-level -flto-report -fltrans @gol
 -fltrans-output-list -fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
 -fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
@@ -382,8 +382,8 @@ Objective-C and Objective-C++ Dialects}.
 -fsplit-wide-types -fstack-protector -fstack-protector-all @gol
 -fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer @gol
 -ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop @gol
--ftree-copyrename -ftree-dce @gol
--ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre -ftree-loop-im @gol
+-ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse @gol
+-ftree-forwprop -ftree-fre -ftree-loop-if-convert -ftree-loop-im @gol
 -ftree-phiprop -ftree-loop-distribution @gol
 -ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
 -ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol
@@ -6883,6 +6883,13 @@ profitable to parallelize the loops.
 Compare the results of several data dependence analyzers.  This option
 is used for debugging the data dependence analyzers.
 
+@item -ftree-loop-if-convert
+Attempt to transform conditional jumps in the innermost loops to
+branch-less equivalents.  The intent is to remove control-flow from
+the innermost loops in order to improve the ability of the
+vectorization pass to handle these loops.  This is enabled by default
+if vectorization is enabled.
+
 @item -ftree-loop-distribution
 Perform loop distribution.  This flag can improve cache performance on
 big loop bodies and allow further loop optimizations, like
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 8d5d226..2dd8aa1 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -1239,10 +1239,13 @@ main_tree_if_conversion (void)
   return changed ? TODO_cleanup_cfg : 0;
 }
 
+/* Returns true when the if-conversion pass is enabled.  */
+
 static bool
 gate_tree_if_conversion (void)
 {
-  return flag_tree_vectorize != 0;
+  return ((flag_tree_vectorize && flag_tree_loop_if_convert != 0)
+	  || flag_tree_loop_if_convert == 1);
 }
 
 struct gimple_opt_pass pass_if_conversion =