Improve do_store_flag for single bit when there is no non-zero bits

In r14-1534-g908e5ab5c11c, I forgot you could turn off CCP or
turn off the bit tracking part of CCP so we would lose out
what TER was able to do before hand. This moves around the
TER code so that it is used instead of just the nonzerobits.
It also makes it easier to remove the TER part of the code
later on too.

OK? Bootstrapped and tested on x86_64-linux-gnu.

Note it reintroduces PR 110117 (which was accidently fixed after
r14-1534-g908e5ab5c11c). The next patch in series will fix that.

gcc/ChangeLog:

	* expr.cc (do_store_flag): Rearrange the
	TER code so that it overrides the nonzero bits
	info if we had `a & POW2`.

1 files changed, 11 insertions, 17 deletions

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 4efb991..1c5874b 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -13158,38 +13158,32 @@ do_store_flag (sepops ops, rtx target, machine_mode mode)
       && (TYPE_PRECISION (ops->type) != 1 || TYPE_UNSIGNED (ops->type)))
     {
       wide_int nz = tree_nonzero_bits (arg0);
+      gimple *srcstmt = get_def_for_expr (arg0, BIT_AND_EXPR);
+      /* If the defining statement was (x & POW2), then use that instead of
+	 the non-zero bits.  */
+      if (srcstmt && integer_pow2p (gimple_assign_rhs2 (srcstmt)))
+	{
+	  nz = wi::to_wide (gimple_assign_rhs2 (srcstmt));
+	  arg0 = gimple_assign_rhs1 (srcstmt);
+	}
 
       if (wi::popcount (nz) == 1
 	  && (integer_zerop (arg1)
 	      || wi::to_wide (arg1) == nz))
 	{
-	  tree op0;
-	  int bitnum;
-	  gimple *srcstmt = get_def_for_expr (arg0, BIT_AND_EXPR);
-	  /* If the defining statement was (x & POW2), then remove the and
-	     as we are going to add it back. */
-	  if (srcstmt
-	      && integer_pow2p (gimple_assign_rhs2 (srcstmt)))
-	    {
-	      op0 = gimple_assign_rhs1 (srcstmt);
-	      bitnum = tree_log2 (gimple_assign_rhs2 (srcstmt));
-	    }
-	  else
-	    {
-	      op0 = arg0;
-	      bitnum = wi::exact_log2 (nz);
-	    }
+	  int bitnum = wi::exact_log2 (nz);
 	  enum tree_code tcode = EQ_EXPR;
 	  if ((code == NE) ^ !integer_zerop (arg1))
 	    tcode = NE_EXPR;
 
 	  type = lang_hooks.types.type_for_mode (mode, unsignedp);
 	  return expand_single_bit_test (loc, tcode,
-					 op0,
+					 arg0,
 					 bitnum, type, target, mode);
 	}
     }
 
+
   if (! get_subtarget (target)
       || GET_MODE (subtarget) != operand_mode)
     subtarget = 0;