[Patch] New hook TARGET_STACK_PROTECT_RUNTIME_ENABLED_P to disable SSP runtime

gcc/
	* target.def (stack_protect_runtime_enabled_p): New.
	* function.c (expand_function_end): Guard stack_protect_epilogue with
	targetm.stack_protect_runtime_enabled_p.
	* cfgexpand.c (pass_expand::execute): Likewise.
	* calls.c (expand_call): Likewise.
	* doc/tm.texi.in (TARGET_STACK_PROTECT_RUNTIME_ENABLED_P): Add it.
	* doc/tm.texi: Regenerate.

From-SVN: r242955

7 files changed, 30 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c1dd877..b7ccbd8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2016-11-29  Jiong Wang  <jiong.wang@arm.com>
+
+	* target.def (stack_protect_runtime_enabled_p): New.
+	* function.c (expand_function_end): Guard stack_protect_epilogue with
+	targetm.stack_protect_runtime_enabled_p.
+	* cfgexpand.c (pass_expand::execute): Likewise.
+	* calls.c (expand_call): Likewise.
+	* doc/tm.texi.in (TARGET_STACK_PROTECT_RUNTIME_ENABLED_P): Add it.
+	* doc/tm.texi: Regenerate.
+
 2016-11-29  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/78546
diff --git a/gcc/calls.c b/gcc/calls.c
index c916e07..21385ce 100644
--- a/gcc/calls.c
+++ b/gcc/calls.c
@@ -3083,7 +3083,9 @@ expand_call (tree exp, rtx target, int ignore)
       if (pass && (flags & ECF_MALLOC))
 	start_sequence ();
 
-      if (pass == 0 && crtl->stack_protect_guard)
+      if (pass == 0
+	  && crtl->stack_protect_guard
+	  && targetm.stack_protect_runtime_enabled_p ())
 	stack_protect_epilogue ();
 
       adjusted_args_size = args_size;
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 9cca611..c3aca59 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -6334,7 +6334,7 @@ pass_expand::execute (function *fun)
 
   /* Initialize the stack_protect_guard field.  This must happen after the
      call to __main (if any) so that the external decl is initialized.  */
-  if (crtl->stack_protect_guard)
+  if (crtl->stack_protect_guard && targetm.stack_protect_runtime_enabled_p ())
     stack_protect_prologue ();
 
   expand_phi_nodes (&SA);
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index ebcadac..7559c12 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -4946,6 +4946,10 @@ The default version of this hook invokes a function called
 normally defined in @file{libgcc2.c}.
 @end deftypefn
 
+@deftypefn {Target Hook} bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+Returns true if the target wants GCC's default stack protect runtime support, otherwise return false.  The default implementation always returns true.
+@end deftypefn
+
 @deftypefn {Common Target Hook} bool TARGET_SUPPORTS_SPLIT_STACK (bool @var{report}, struct gcc_options *@var{opts})
 Whether this target supports splitting the stack when the options described in @var{opts} have been passed.  This is called after options have been parsed, so the target may reject splitting the stack in some configurations.  The default version of this hook returns false.  If @var{report} is true, this function may issue a warning or error; if @var{report} is false, it must simply return a value
 @end deftypefn
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 95f5fd9..bc6d3cb 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -3820,6 +3820,8 @@ generic code.
 
 @hook TARGET_STACK_PROTECT_FAIL
 
+@hook TARGET_STACK_PROTECT_RUNTIME_ENABLED_P
+
 @hook TARGET_SUPPORTS_SPLIT_STACK
 
 @node Miscellaneous Register Hooks
diff --git a/gcc/function.c b/gcc/function.c
index c5a538f..0829fbe 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -5635,7 +5635,7 @@ expand_function_end (void)
     emit_insn (gen_blockage ());
 
   /* If stack protection is enabled for this function, check the guard.  */
-  if (crtl->stack_protect_guard)
+  if (crtl->stack_protect_guard && targetm.stack_protect_runtime_enabled_p ())
     stack_protect_epilogue ();
 
   /* If we had calls to alloca, and this machine needs
diff --git a/gcc/target.def b/gcc/target.def
index 85a0ac0..417cd02 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -4039,6 +4039,15 @@ normally defined in @file{libgcc2.c}.",
  tree, (void),
  default_external_stack_protect_fail)
 
+/* This target hook allows the operating system to disable the default stack
+   protector runtime support.  */
+DEFHOOK
+(stack_protect_runtime_enabled_p,
+ "Returns true if the target wants GCC's default stack protect runtime support,\
+ otherwise return false.  The default implementation always returns true.",
+ bool, (void),
+ hook_bool_void_true)
+
 DEFHOOK
 (can_use_doloop_p,
  "Return true if it is possible to use low-overhead loops (@code{doloop_end}\n\