[Bug rtl-optimization/50696] [x32] Unnecessary lea

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50696

--- Comment #5 from H.J. Lu <hjl.tools at gmail dot com> 2011-10-11 23:29:05 UTC ---
This patch changes combine not to generate:

(plus:DI (subreg:DI (mult:SI (reg/v:SI 85 [ i ])
            (const_int 4 [0x4])) 0)
    (subreg:DI (reg:SI 100) 0))

and changes const_32bit_mask to match what combine may generate:

diff --git a/gcc/combine.c b/gcc/combine.c
index 6c3b17c..147d158 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -6905,10 +6905,17 @@ expand_compound_operation (rtx x)
       tem = gen_lowpart (mode, XEXP (x, 0));
       if (!tem || GET_CODE (tem) == CLOBBER)
     return x;
-      tem = simplify_shift_const (NULL_RTX, ASHIFT, mode,
-                  tem, modewidth - pos - len);
-      tem = simplify_shift_const (NULL_RTX, unsignedp ? LSHIFTRT : ASHIFTRT,
-                  mode, tem, modewidth - len);
+      if (GET_CODE (x) == ZERO_EXTEND)
+    tem = gen_rtx_AND (mode, tem,
+               GEN_INT (GET_MODE_MASK (GET_MODE (XEXP (x, 0)))));
+      else
+    {
+      tem = simplify_shift_const (NULL_RTX, ASHIFT, mode,
+                      tem, modewidth - pos - len);
+      tem = simplify_shift_const (NULL_RTX,
+                      unsignedp ? LSHIFTRT : ASHIFTRT,
+                      mode, tem, modewidth - len);
+    }
     }
   else if (unsignedp && len < HOST_BITS_PER_WIDE_INT)
     tem = simplify_and_const_int (NULL_RTX, GET_MODE (x),
diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
index 349f5b0..03da1fb 100644
--- a/gcc/config/i386/predicates.md
+++ b/gcc/config/i386/predicates.md
@@ -600,8 +600,8 @@
 ;; Match exactly 0x0FFFFFFFF in anddi as a zero-extension operation
 (define_predicate "const_32bit_mask"
   (and (match_code "const_int")
-       (match_test "trunc_int_for_mode (INTVAL (op), DImode)
-            == (HOST_WIDE_INT) 0xffffffff")))
+       (match_test "(trunc_int_for_mode (INTVAL (op), DImode) &
(HOST_WIDE_INT)
 0xffffff00)
+            == (HOST_WIDE_INT) 0xffffff00")))

 ;; Match 2, 4, or 8.  Used for leal multiplicands.
 (define_predicate "const248_operand"