combine.c (if_then_else_cond): Canonicalize BImode true to STORE_FLAG_VALUE.

        * combine.c (if_then_else_cond): Canonicalize BImode true to
        STORE_FLAG_VALUE.
        * explow.c (trunc_int_for_mode): Likewise.

From-SVN: r36507

gcc/ChangeLog

 2000-09-18  Richard Henderson  <rth@cygnus.com>
 
+	* combine.c (if_then_else_cond): Canonicalize BImode true to
+	STORE_FLAG_VALUE.
+	* explow.c (trunc_int_for_mode): Likewise.
+
 	* combine.c (combine_simplify_rtx): Use gen_unary to distribute
 	the NOT for De Morgan's rule.
 	* simplify-rtx.c (simplify_unary_operation): Simplify a BImode NOT

gcc/combine.c

@@ -7418,6 +7418,14 @@ if_then_else_cond (x, ptrue, pfalse)
 	   || ((cond0 = get_last_value (x)) != 0 && CONSTANT_P (cond0)))
     ;
 
+  /* If we're in BImode, canonicalize on 0 and STORE_FLAG_VALUE, as that
+     will be least confusing to the rest of the compiler.  */
+  else if (mode == BImode)
+    {
+      *ptrue = GEN_INT (STORE_FLAG_VALUE), *pfalse = const0_rtx;
+      return x;
+    }
+
   /* If X is known to be either 0 or -1, those are the true and
      false values when testing X.  */
   else if (x == constm1_rtx || x == const0_rtx

gcc/explow.c

@@ -52,6 +52,10 @@ trunc_int_for_mode (c, mode)
 {
   int width = GET_MODE_BITSIZE (mode);
 
+  /* Canonicalize BImode to 0 and STORE_FLAG_VALUE.  */
+  if (mode == BImode)
+    return c & 1 ? STORE_FLAG_VALUE : 0;
+
   /* We clear out all bits that don't belong in MODE, unless they and our
      sign bit are all one.  So we get either a reasonable negative
      value or a reasonable unsigned value.  */