[committed][PATCH] Stack clash protection patch 02b/08 - V4

[Jeff Law <law at redhat dot com>]

The only change since V3 of this patch was to fix a typo in the sparc.c
changes.

The purpose of this patch is to allow targets that are not going to have
stack-clash protected prologues to use their -fstack-check=specific
prologue support to provide a degree of protection for their prologue
stack allocations.

This affects alpha, arm, ia64, mips, sparc and spu.   I have not
bootstrapped this patch, though I have built one cross for each target
to verify buildability.

Installing on the trunk.

Jeff

commit 42565dde29b63f74e92194a1cb5aa0edb33916a4
Author: Jeff Law <law@torsion.usersys.redhat.com>
Date:   Tue Jul 18 11:10:16 2017 -0400

            * config/alpha/alpha.c (alpha_expand_prologue): Also check
            flag_stack_clash_protection.
            * config/arm/arm.c (arm_compute_static_chain_stack_bytes): Likewise.
            (arm_expand_prologue, thumb1_expand_prologue): Likewise.
            (arm_frame_pointer_required): Likewise.
            * config/ia64/ia64.c (ia64_compute_frame_size): Likewise.
            (ia64_expand_prologue): Likewise.
            * config/mips/mips.c (mips_expand_prologue): Likewise.
            * config/powerpcspe/powerpcspe.c (rs6000_expand_prologue): Likewise.
            * config/sparc/sparc.c (sparc_expand_prologue): Likewise.
            (sparc_flat_expand_prologue): Likewise.
            * config/spu/spu.c (spu_expand_prologue): Likewise.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b8012611405..070692c5053 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,18 @@
 2017-09-19  Jeff Law  <law@redhat.com>
 
+	* config/alpha/alpha.c (alpha_expand_prologue): Also check
+	flag_stack_clash_protection.
+	* config/arm/arm.c (arm_compute_static_chain_stack_bytes): Likewise.
+	(arm_expand_prologue, thumb1_expand_prologue): Likewise.
+	(arm_frame_pointer_required): Likewise.
+	* config/ia64/ia64.c (ia64_compute_frame_size): Likewise.
+	(ia64_expand_prologue): Likewise.
+	* config/mips/mips.c (mips_expand_prologue): Likewise.
+	* config/powerpcspe/powerpcspe.c (rs6000_expand_prologue): Likewise.
+	* config/sparc/sparc.c (sparc_expand_prologue): Likewise.
+	(sparc_flat_expand_prologue): Likewise.
+	* config/spu/spu.c (spu_expand_prologue): Likewise.
+
 	* explow.c: Include "params.h".
 	(anti_adjust_stack_and_probe_stack_clash): New function.
 	(get_stack_check_protect): Likewise.
diff --git a/gcc/config/alpha/alpha.c b/gcc/config/alpha/alpha.c
index a4e8b2b6c30..41f3e3a1957 100644
--- a/gcc/config/alpha/alpha.c
+++ b/gcc/config/alpha/alpha.c
@@ -7760,7 +7760,7 @@ alpha_expand_prologue (void)
      Note that we are only allowed to adjust sp once in the prologue.  */
 
   probed_size = frame_size;
-  if (flag_stack_check)
+  if (flag_stack_check || flag_stack_clash_protection)
     probed_size += get_stack_check_protect ();
 
   if (probed_size <= 32768)
@@ -7775,7 +7775,7 @@ alpha_expand_prologue (void)
 	  /* We only have to do this probe if we aren't saving registers or
 	     if we are probing beyond the frame because of -fstack-check.  */
 	  if ((sa_size == 0 && probed_size > probed - 4096)
-	      || flag_stack_check)
+	      || flag_stack_check || flag_stack_clash_protection)
 	    emit_insn (gen_probe_stack (GEN_INT (-probed_size)));
 	}
 
@@ -7805,7 +7805,8 @@ alpha_expand_prologue (void)
 	 late in the compilation, generate the loop as a single insn.  */
       emit_insn (gen_prologue_stack_probe_loop (count, ptr));
 
-      if ((leftover > 4096 && sa_size == 0) || flag_stack_check)
+      if ((leftover > 4096 && sa_size == 0)
+	  || flag_stack_check || flag_stack_clash_protection)
 	{
 	  rtx last = gen_rtx_MEM (DImode,
 				  plus_constant (Pmode, ptr, -leftover));
@@ -7813,7 +7814,7 @@ alpha_expand_prologue (void)
 	  emit_move_insn (last, const0_rtx);
 	}
 
-      if (flag_stack_check)
+      if (flag_stack_check || flag_stack_clash_protection)
 	{
 	  /* If -fstack-check is specified we have to load the entire
 	     constant into a register and subtract from the sp in one go,
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 679e838b0aa..d97f88719c5 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -19164,7 +19164,8 @@ arm_compute_static_chain_stack_bytes (void)
   /* See the defining assertion in arm_expand_prologue.  */
   if (IS_NESTED (arm_current_func_type ())
       && ((TARGET_APCS_FRAME && frame_pointer_needed && TARGET_ARM)
-	  || (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+	  || ((flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+	       || flag_stack_clash_protection)
 	      && !df_regs_ever_live_p (LR_REGNUM)))
       && arm_r3_live_at_start_p ()
       && crtl->args.pretend_args_size == 0)
@@ -21466,7 +21467,8 @@ arm_expand_prologue (void)
      clobbered when creating the frame, we need to save and restore it.  */
   clobber_ip = IS_NESTED (func_type)
 	       && ((TARGET_APCS_FRAME && frame_pointer_needed && TARGET_ARM)
-		   || (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+		   || ((flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+			|| flag_stack_clash_protection)
 		       && !df_regs_ever_live_p (LR_REGNUM)
 		       && arm_r3_live_at_start_p ()));
 
@@ -21680,7 +21682,8 @@ arm_expand_prologue (void)
      stack checking.  We use IP as the first scratch register, except for the
      non-APCS nested functions if LR or r3 are available (see clobber_ip).  */
   if (!IS_INTERRUPT (func_type)
-      && flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+      && (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+	  || flag_stack_clash_protection))
     {
       unsigned int regno;
 
@@ -24991,7 +24994,9 @@ thumb1_expand_prologue (void)
     current_function_static_stack_size = size;
 
   /* If we have a frame, then do stack checking.  FIXME: not implemented.  */
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK && size)
+  if ((flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+       || flag_stack_clash_protection)
+      && size)
     sorry ("-fstack-check=specific for Thumb-1");
 
   amount = offsets->outgoing_args - offsets->saved_regs;
@@ -27871,7 +27876,8 @@ arm_frame_pointer_required (void)
      instruction prior to the stack adjustment and this requires a frame
      pointer if we want to catch the exception using the EABI unwinder.  */
   if (!IS_INTERRUPT (arm_current_func_type ())
-      && flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      && (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+	  || flag_stack_clash_protection)
       && arm_except_unwind_info (&global_options) == UI_TARGET
       && cfun->can_throw_non_call_exceptions)
     {
diff --git a/gcc/config/ia64/ia64.c b/gcc/config/ia64/ia64.c
index 00ef2159323..f34f2f85247 100644
--- a/gcc/config/ia64/ia64.c
+++ b/gcc/config/ia64/ia64.c
@@ -2704,7 +2704,8 @@ ia64_compute_frame_size (HOST_WIDE_INT size)
     mark_reg_gr_used_mask (cfun->machine->ia64_eh_epilogue_bsp, NULL);
 
   /* Static stack checking uses r2 and r3.  */
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      || flag_stack_clash_protection)
     current_frame_info.gr_used_mask |= 0xc;
 
   /* Find the size of the register stack frame.  We have only 80 local
@@ -3494,7 +3495,8 @@ ia64_expand_prologue (void)
   if (flag_stack_usage_info)
     current_function_static_stack_size = current_frame_info.total_size;
 
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      || flag_stack_clash_protection)
     {
       HOST_WIDE_INT size = current_frame_info.total_size;
       int bs_size = BACKING_STORE_SIZE (current_frame_info.n_input_regs
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 67cee0bb051..8643cb9ad30 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -12080,7 +12080,8 @@ mips_expand_prologue (void)
   if (flag_stack_usage_info)
     current_function_static_stack_size = size;
 
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      || flag_stack_clash_protection)
     {
       if (crtl->is_leaf && !cfun->calls_alloca)
 	{
diff --git a/gcc/config/powerpcspe/powerpcspe.c b/gcc/config/powerpcspe/powerpcspe.c
index a956729f706..e235d3c6a82 100644
--- a/gcc/config/powerpcspe/powerpcspe.c
+++ b/gcc/config/powerpcspe/powerpcspe.c
@@ -29687,7 +29687,8 @@ rs6000_emit_prologue (void)
   if (flag_stack_usage_info)
     current_function_static_stack_size = info->total_size;
 
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      || flag_stack_check_protection)
     {
       HOST_WIDE_INT size = info->total_size;
 
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 906bd75b560..11e4f4565a5 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -5734,7 +5734,8 @@ sparc_expand_prologue (void)
   if (flag_stack_usage_info)
     current_function_static_stack_size = size;
 
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      || flag_stack_clash_protection)
     {
       if (crtl->is_leaf && !cfun->calls_alloca)
 	{
@@ -5845,7 +5846,8 @@ sparc_flat_expand_prologue (void)
   if (flag_stack_usage_info)
     current_function_static_stack_size = size;
 
-  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK)
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK
+      || flag_stack_clash_protection)
     {
       if (crtl->is_leaf && !cfun->calls_alloca)
 	{
diff --git a/gcc/config/spu/spu.c b/gcc/config/spu/spu.c
index a35f0b8636b..1fc99772286 100644
--- a/gcc/config/spu/spu.c
+++ b/gcc/config/spu/spu.c
@@ -1767,7 +1767,7 @@ spu_expand_prologue (void)
 
   if (total_size > 0)
     {
-      if (flag_stack_check)
+      if (flag_stack_check || flag_stack_clash_protection)
 	{
 	  /* We compare against total_size-1 because
 	     ($sp >= total_size) <=> ($sp > total_size-1) */
@@ -5390,7 +5390,7 @@ spu_allocate_stack (rtx op0, rtx op1)
   emit_insn (gen_spu_convert (sp, stack_pointer_rtx));
   emit_insn (gen_subv4si3 (sp, sp, splatted));
 
-  if (flag_stack_check)
+  if (flag_stack_check || flag_stack_clash_protection)
     {
       rtx avail = gen_reg_rtx(SImode);
       rtx result = gen_reg_rtx(SImode);