[PATCH, i386]: Remove UNSPEC_STACK_CHECK ...

[Uros Bizjak <ubizjak@gmail.com>]

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... and use address spaces to load boundary value from TLS block.

The patch removes special handling for boundary value location.

2017-08-10  Uros Bizjak  <ubizjak@gmail.com>

    * config/i386/i386-protos.h (ix86_split_stack_boundary): New prototype.
    * config/i386/i386.c (ix86_split_stack_boundary): New function.
    (ix86_xpand_split_stack_prologue): Call ix86_split_stack_boundary.
    (ix86_legitimate_address_p) <case UNSPEC_STACK_CHECK>: Remove.
    (i386_asm_output_addr_const_extra) <case UNSPEC_STACK_CHECK>: Ditto.
    (optput_pic_addr_const): Remove UNSPEC_STACK_CHECK handling.
    * config/i386/i386.md (unspec): Remove UNSPEC_STACK_CHECK.
    (split_stack_space_check): Call ix86_split_stack_boundary.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32} with
all default languages plus go.

Committed to mainline SVN.

Uros.

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Index: config/i386/i386-protos.h
===================================================================
--- config/i386/i386-protos.h	(revision 251027)
+++ config/i386/i386-protos.h	(working copy)
@@ -201,6 +201,8 @@ extern void ix86_expand_truncdf_32 (rtx, rtx);
 
 extern void ix86_expand_vecop_qihi (enum rtx_code, rtx, rtx, rtx);
 
+extern rtx ix86_split_stack_boundary (void);
+
 #ifdef TREE_CODE
 extern void init_cumulative_args (CUMULATIVE_ARGS *, tree, rtx, tree, int);
 #endif	/* TREE_CODE  */
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 251027)
+++ config/i386/i386.c	(working copy)
@@ -15784,6 +15784,28 @@ static GTY(()) rtx split_stack_fn;
 
 static GTY(()) rtx split_stack_fn_large;
 
+/*  */
+
+rtx
+ix86_split_stack_boundary (void)
+{
+  int offset;
+  addr_space_t as = DEFAULT_TLS_SEG_REG;
+  rtx r;
+
+#ifdef TARGET_THREAD_SPLIT_STACK_OFFSET
+  offset = TARGET_THREAD_SPLIT_STACK_OFFSET;
+#else
+  gcc_unreachable ();
+#endif
+
+  r = GEN_INT (offset);
+  r = gen_const_mem (Pmode, r);
+  set_mem_addr_space (r, as);
+
+  return r;
+}
+
 /* Handle -fsplit-stack.  These are the first instructions in the
    function, even before the regular prologue.  */
 
@@ -15815,10 +15837,8 @@ ix86_expand_split_stack_prologue (void)
      us SPLIT_STACK_AVAILABLE bytes, so if we need less than that we
      can compare directly.  Otherwise we need to do an addition.  */
 
-  limit = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, const0_rtx),
-			  UNSPEC_STACK_CHECK);
-  limit = gen_rtx_CONST (Pmode, limit);
-  limit = gen_rtx_MEM (Pmode, limit);
+  limit = ix86_split_stack_boundary ();
+
   if (allocate < SPLIT_STACK_AVAILABLE)
     current = stack_pointer_rtx;
   else
@@ -16891,10 +16911,6 @@ ix86_legitimate_address_p (machine_mode, rtx addr,
 	  case UNSPEC_DTPOFF:
 	    break;
 
-	  case UNSPEC_STACK_CHECK:
-	    gcc_assert (flag_split_stack);
-	    break;
-
 	  default:
 	    /* Invalid address unspec.  */
 	    return false;
@@ -17984,17 +18000,10 @@ output_pic_addr_const (FILE *file, rtx x, int code
 	putc (ASSEMBLER_DIALECT == ASM_INTEL ? ')' : ']', file);
       break;
 
-     case UNSPEC:
-       if (XINT (x, 1) == UNSPEC_STACK_CHECK)
-	 {
-	   bool f = i386_asm_output_addr_const_extra (file, x);
-	   gcc_assert (f);
-	   break;
-	 }
-
-       gcc_assert (XVECLEN (x, 0) == 1);
-       output_pic_addr_const (file, XVECEXP (x, 0, 0), code);
-       switch (XINT (x, 1))
+    case UNSPEC:
+      gcc_assert (XVECLEN (x, 0) == 1);
+      output_pic_addr_const (file, XVECEXP (x, 0, 0), code);
+      switch (XINT (x, 1))
 	{
 	case UNSPEC_GOT:
 	  fputs ("@GOT", file);
@@ -19690,22 +19699,6 @@ i386_asm_output_addr_const_extra (FILE *file, rtx
       break;
 #endif
 
-    case UNSPEC_STACK_CHECK:
-      {
-	int offset;
-
-	gcc_assert (flag_split_stack);
-
-#ifdef TARGET_THREAD_SPLIT_STACK_OFFSET
-	offset = TARGET_THREAD_SPLIT_STACK_OFFSET;
-#else
-	gcc_unreachable ();
-#endif
-
-	fprintf (file, "%s:%d", TARGET_64BIT ? "%fs" : "%gs", offset);
-      }
-      break;
-
     default:
       return false;
     }
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md	(revision 251027)
+++ config/i386/i386.md	(working copy)
@@ -86,7 +86,6 @@
   UNSPEC_SET_RIP
   UNSPEC_SET_GOT_OFFSET
   UNSPEC_MEMORY_BLOCKAGE
-  UNSPEC_STACK_CHECK
   UNSPEC_PROBE_STACK
 
   ;; TLS support
@@ -12630,21 +12629,18 @@
   [(set (pc) (if_then_else
 	      (ltu (minus (reg SP_REG)
 			  (match_operand 0 "register_operand"))
-		   (unspec [(const_int 0)] UNSPEC_STACK_CHECK))
+		   (match_dup 2))
 	      (label_ref (match_operand 1))
 	      (pc)))]
   ""
 {
-  rtx reg, size, limit;
+  rtx reg = gen_reg_rtx (Pmode);
 
-  reg = gen_reg_rtx (Pmode);
-  size = force_reg (Pmode, operands[0]);
-  emit_insn (gen_sub3_insn (reg, stack_pointer_rtx, size));
-  limit = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, const0_rtx),
-			  UNSPEC_STACK_CHECK);
-  limit = gen_rtx_MEM (Pmode, gen_rtx_CONST (Pmode, limit));
-  ix86_expand_branch (GEU, reg, limit, operands[1]);
+  emit_insn (gen_sub3_insn (reg, stack_pointer_rtx, operands[0]));
 
+  operands[2] = ix86_split_stack_boundary ();
+  ix86_expand_branch (GEU, reg, operands[2], operands[1]);
+
   DONE;
 })
 \f