c4x.c (c4x_expand_prologue): Don't compile an ISR with more than 32767 words of local storage.

	* config/c4x/c4x.c (c4x_expand_prologue): Don't compile an ISR
	with more than 32767 words of local storage.

From-SVN: r38703

gcc/ChangeLog

 2001-01-05  Michael Hayes  <m.hayes@elec.canterbury.ac.nz>
 
+	* config/c4x/c4x.c (c4x_expand_prologue): Don't compile an ISR
+	with more than 32767 words of local storage.
+
+2001-01-05  Michael Hayes  <m.hayes@elec.canterbury.ac.nz>
+
 	* config/c4x/c4x.c (c4x_init_builtins): Remove builtin support
 	for 'abs', 'labs', and 'fabs'.
 	(c4x_expand_builtin): Likewise.

gcc/config/c4x/c4x.c

@@ -826,10 +826,15 @@ c4x_expand_prologue ()
 	  insn = emit_insn (gen_movqi (gen_rtx_REG (QImode, AR3_REGNO),
 				       gen_rtx_REG (QImode, SP_REGNO)));
           RTX_FRAME_RELATED_P (insn) = 1;
-	  /* FIXME: Assume ISR doesn't require more than 32767 words
-	     of local variables.  */
+	  /* We require that an ISR uses fewer than 32768 words of
+	     local variables, otherwise we have to go to lots of
+	     effort to save a register, load it with the desired size,
+	     adjust the stack pointer, and then restore the modified
+	     register.  Frankly, I think it is a poor ISR that
+	     requires more than 32767 words of local temporary
+	     storage!  */
 	  if (size > 32767)
-	    error ("ISR %s requires %d words of local vars, max is 32767.",
+	    fatal ("ISR %s requires %d words of local vars, max is 32767.",
 		   current_function_name, size);
 	  insn = emit_insn (gen_addqi3 (gen_rtx_REG (QImode, SP_REGNO),
 				        gen_rtx_REG (QImode, SP_REGNO),