[PATCH] Restore -ftrapv bootstrap

[Richard Biener]

This reverts part of the earlier patch for PR52478 which turns out
to be not necessary.  It also revealed that at least switch
expansion builds new arithmetic in signed char - going the -ftrapv
expansion way (where we obviously don't have __addvqi3 as C
promotes everything to int).  We probably should be using
unsigned types here.

I chose to do the simple reversion instead of not using
trapv optabs for modes < INT_TYPE_SIZE.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2014-07-29  Richard Biener  <rguenther@suse.de>

	PR middle-end/52478
	* expr.c (expand_expr_real_2): Revert last change.

Index: gcc/expr.c
===================================================================
--- gcc/expr.c	(revision 213119)
+++ gcc/expr.c	(working copy)
@@ -9212,9 +9212,7 @@ expand_expr_real_2 (sepops ops, rtx targ
   if (modifier == EXPAND_STACK_PARM)
     target = 0;
   temp = expand_binop (mode, this_optab, op0, op1, target,
-		       unsignedp,
-		       trapv_binoptab_p (this_optab)
-		       ? OPTAB_LIB : OPTAB_LIB_WIDEN);
+		       unsignedp, OPTAB_LIB_WIDEN);
   gcc_assert (temp);
   /* Bitwise operations do not need bitfield reduction as we expect their
      operands being properly truncated.  */