[rs6000] Fix ICE with -fstack-limit-register and large frames

[Eric Botcazou]

Hi,

this fixes an internal error with -fstack-limit-register and large frames:

eric@polaris:~/build/gcc/powerpc-linux> gcc/xgcc -Bgcc -S stack-limit-1.c -
fstack-limit-register=r2
stack-limit-1.c: In function 'foo':
stack-limit-1.c:9:1: error: insn does not satisfy its constraints:
 }
 ^
(insn 21 20 22 (set (reg:SI 0 0)
        (plus:SI (reg:SI 0 0)
            (const_int 3968 [0xf80]))) "stack-limit-1.c":5 70 {*addsi3}
     (nil))
stack-limit-1.c:9:1: internal compiler error: in final_scan_insn, at 
final.c:2964
0xb40335 _fatal_insn(char const*, rtx_def const*, char const*, int, char 
const*)
        /home/eric/svn/gcc/gcc/rtl-error.c:108
0xb4037a _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        /home/eric/svn/gcc/gcc/rtl-error.c:119
0x83f757 final_scan_insn(rtx_insn*, _IO_FILE*, int, int, int*)
        /home/eric/svn/gcc/gcc/final.c:2964
0x83feb2 final(rtx_insn*, _IO_FILE*, int)
        /home/eric/svn/gcc/gcc/final.c:2051
0x84076d rest_of_handle_final
        /home/eric/svn/gcc/gcc/final.c:4489
0x84076d execute
        /home/eric/svn/gcc/gcc/final.c:4562
Please submit a full bug report,

Tested on PowerPC/Linux, OK for mainline?


2017-05-24  Eric Botcazou  <ebotca...@adacore.com>

        * config/rs6000/rs6000.c (rs6000_emit_allocate_stack): Deal properly
        with large frames if a stack limit is used.


2017-05-24  Eric Botcazou  <ebotca...@adacore.com>

        * gcc.target/powerpc/stack-limit-1.c: New test.

-- 
Eric Botcazou
Index: config/rs6000/rs6000.c
===================================================================
--- config/rs6000/rs6000.c	(revision 248140)
+++ config/rs6000/rs6000.c	(working copy)
@@ -28372,7 +28372,21 @@ rs6000_emit_allocate_stack (HOST_WIDE_IN
 	  && REGNO (stack_limit_rtx) > 1
 	  && REGNO (stack_limit_rtx) <= 31)
 	{
-	  emit_insn (gen_add3_insn (tmp_reg, stack_limit_rtx, GEN_INT (size)));
+	  rtx cst = GEN_INT (size);
+
+	  /* The add expander doesn't correctly handle r0.  */
+	  if (satisfies_constraint_I (cst))
+	    emit_insn (gen_rtx_SET (tmp_reg,
+				    gen_rtx_PLUS (Pmode, stack_limit_rtx,
+						  cst)));
+	  else
+	    {
+	      emit_move_insn (tmp_reg, cst);
+	      emit_insn (gen_rtx_SET (tmp_reg,
+				      gen_rtx_PLUS (Pmode, stack_limit_rtx,
+						    tmp_reg)));
+	    }
+
 	  emit_insn (gen_cond_trap (LTU, stack_reg, tmp_reg,
 				    const0_rtx));
 	}

/* { dg-do compile } */
/* { dg-options "-fstack-limit-register=r2" } */

int foo (int i)
{
  char arr[135000];

  arr[i] = 0;
}