Add fstdarg-opt

2015-02-18  Tom de Vries  <tom@codesourcery.com>

	* common.opt (fstdarg-opt): New option.
	* tree-stdarg.c (pass_stdarg::gate): Use flag_stdarg_opt.
	* doc/invoke.texi (@item Optimization Options): Add -fstdarg-opt.
	(@item -fstdarg-opt): New item.

From-SVN: r220800

gcc/ChangeLog

+2015-02-18  Tom de Vries  <tom@codesourcery.com>
+
+	* common.opt (fstdarg-opt): New option.
+	* tree-stdarg.c (pass_stdarg::gate): Use flag_stdarg_opt.
+	* doc/invoke.texi (@item Optimization Options): Add -fstdarg-opt.
+	(@item -fstdarg-opt): New item.
+
 2015-02-18  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/65064

gcc/common.opt

@@ -2069,6 +2069,10 @@ fssa-phiopt
 Common Report Var(flag_ssa_phiopt) Optimization
 Optimize conditional patterns using SSA PHI nodes
 
+fstdarg-opt
+Common Report Var(flag_stdarg_opt) Init(1) Optimization
+Optimize amount of stdarg registers saved to stack at start of function
+
 fvariable-expansion-in-unroller
 Common Report Var(flag_variable_expansion_in_unroller) Optimization
 Apply variable expansion when loops are unrolled

gcc/doc/invoke.texi

@@ -430,7 +430,7 @@ Objective-C and Objective-C++ Dialects}.
 -fshrink-wrap -fsignaling-nans -fsingle-precision-constant @gol
 -fsplit-ivs-in-unroller -fsplit-wide-types -fssa-phiopt @gol
 -fstack-protector -fstack-protector-all -fstack-protector-strong @gol
--fstack-protector-explicit -fstrict-aliasing @gol
+-fstack-protector-explicit -fstdarg-opt -fstrict-aliasing @gol
 -fstrict-overflow -fthread-jumps -ftracer -ftree-bit-ccp @gol
 -ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
 -ftree-coalesce-inline-vars -ftree-coalesce-vars -ftree-copy-prop @gol
@@ -9867,6 +9867,11 @@ references to local frame addresses.
 Like @option{-fstack-protector} but only protects those functions which
 have the @code{stack_protect} attribute
 
+@item -fstdarg-opt
+@opindex fstdarg-opt
+Optimize the prologue of variadic argument functions with respect to usage of
+those arguments.
+
 @item -fsection-anchors
 @opindex fsection-anchors
 Try to reduce the number of symbolic address calculations by using

gcc/tree-stdarg.c

@@ -704,8 +704,9 @@ public:
   /* opt_pass methods: */
   virtual bool gate (function *fun)
     {
-      /* This optimization is only for stdarg functions.  */
-      return fun->stdarg != 0;
+      return (flag_stdarg_opt
+	      /* This optimization is only for stdarg functions.  */
+	      && fun->stdarg != 0);
     }
 
   virtual unsigned int execute (function *);