[PATCH] Remove -ftree-loop-if-convert-stores

[Richard Biener]

This removes a no longer used option, whether we if-convert stores
now depends on --param allow-store-data-races and/or the availability
of masked stores.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2016-11-17  Richard Biener  <rguent...@suse.de>

        * common.opt (ftree-loop-if-convert-stores): Mark as preserved for
        backward compatibility.
        * doc/invoke.texi (ftree-loop-if-convert-stores): Remove.
        * tree-if-conv.c (pass_if_conversion::gate): Do not test
        flag_tree_loop_if_convert_stores.
        (pass_if_conversion::execute): Likewise.

diff --git a/gcc/common.opt b/gcc/common.opt
index 5e8d72d..1fa3629 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1526,8 +1526,8 @@ Common Report Var(flag_tree_loop_if_convert) Init(-1) 
Optimization
 Convert conditional jumps in innermost loops to branchless equivalents.
 
 ftree-loop-if-convert-stores
-Common Report Var(flag_tree_loop_if_convert_stores) Optimization
-Also if-convert conditional jumps containing memory writes.
+Common Ignore
+Does nothing. Preserved for backward compatibility.
 
 ; -finhibit-size-directive inhibits output of .size for ELF.
 ; This is used only for compiling crtstuff.c,
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 620225c..e6c3dc2 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -412,7 +412,7 @@ Objective-C and Objective-C++ Dialects}.
 -ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
 -ftree-coalesce-vars -ftree-copy-prop -ftree-dce -ftree-dominator-opts @gol
 -ftree-dse -ftree-forwprop -ftree-fre -fcode-hoisting -ftree-loop-if-convert 
@gol
--ftree-loop-if-convert-stores -ftree-loop-im @gol
+-ftree-loop-im @gol
 -ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
 -ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
 -ftree-loop-vectorize @gol
@@ -8061,24 +8061,6 @@ 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-if-convert-stores
-@opindex ftree-loop-if-convert-stores
-Attempt to also if-convert conditional jumps containing memory writes.
-This transformation can be unsafe for multi-threaded programs as it
-transforms conditional memory writes into unconditional memory writes.
-For example,
-@smallexample
-for (i = 0; i < N; i++)
-  if (cond)
-    A[i] = expr;
-@end smallexample
-is transformed to
-@smallexample
-for (i = 0; i < N; i++)
-  A[i] = cond ? expr : A[i];
-@end smallexample
-potentially producing data races.
-
 @item -ftree-loop-distribution
 @opindex ftree-loop-distribution
 Perform loop distribution.  This flag can improve cache performance on
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 46d6b34..dc97fc4 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -2872,8 +2872,7 @@ pass_if_conversion::gate (function *fun)
 {
   return (((flag_tree_loop_vectorize || fun->has_force_vectorize_loops)
           && flag_tree_loop_if_convert != 0)
-         || flag_tree_loop_if_convert == 1
-         || flag_tree_loop_if_convert_stores == 1);
+         || flag_tree_loop_if_convert == 1);
 }
 
 unsigned int
@@ -2887,7 +2886,6 @@ pass_if_conversion::execute (function *fun)
 
   FOR_EACH_LOOP (loop, 0)
     if (flag_tree_loop_if_convert == 1
-       || flag_tree_loop_if_convert_stores == 1
        || ((flag_tree_loop_vectorize || loop->force_vectorize)
            && !loop->dont_vectorize))
       todo |= tree_if_conversion (loop);