[PATCH] Fix up r217118 - simplify_binary_operation_1 (PR rtl-optimization/63843)

[Jakub Jelinek]

Hi!

The case ASHIFTRT: which is meant for this optimization is preceeded by
/* FALLTHRU */ from ROTATE cases, which can't be optimized this way.
Thus, this patch limits this optimization to ASHIFTRT.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2014-11-18  Jakub Jelinek  <ja...@redhat.com>

        PR rtl-optimization/63843
        * simplify-rtx.c (simplify_binary_operation_1) <case ASHIFTRT>: For
        optimization of ashiftrt of subreg of lshiftrt, check that code
        is ASHIFTRT.

        * gcc.c-torture/execute/pr63843.c: New test.

--- gcc/simplify-rtx.c.jj       2014-11-18 10:17:01.000000000 +0100
+++ gcc/simplify-rtx.c  2014-11-18 13:44:26.727792683 +0100
@@ -3118,10 +3118,11 @@ simplify_binary_operation_1 (enum rtx_co
          (subreg:M1 (ashiftrt:M2 (reg:M2)
                                  (const_int <c1 + c2>))
           <low_part>).  */
-      if (!VECTOR_MODE_P (mode)
+      if (code == ASHIFTRT
+         && !VECTOR_MODE_P (mode)
           && SUBREG_P (op0)
           && CONST_INT_P (op1)
-          && (GET_CODE (SUBREG_REG (op0)) == LSHIFTRT)
+         && GET_CODE (SUBREG_REG (op0)) == LSHIFTRT
           && !VECTOR_MODE_P (GET_MODE (SUBREG_REG (op0)))
           && CONST_INT_P (XEXP (SUBREG_REG (op0), 1))
           && (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0)))
--- gcc/testsuite/gcc.c-torture/execute/pr63843.c.jj    2014-11-18 
13:43:45.417544096 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr63843.c       2014-11-18 
13:43:32.000000000 +0100
@@ -0,0 +1,31 @@
+/* PR rtl-optimization/63843 */
+
+static inline __attribute__ ((always_inline))
+unsigned short foo (unsigned short v)
+{
+  return (v << 8) | (v >> 8);
+}
+
+unsigned short __attribute__ ((noinline, noclone, hot))
+bar (unsigned char *x)
+{
+  unsigned int a;
+  unsigned short b;
+  __builtin_memcpy (&a, &x[0], sizeof (a));
+  a ^= 0x80808080U;
+  __builtin_memcpy (&x[0], &a, sizeof (a));
+  __builtin_memcpy (&b, &x[2], sizeof (b));
+  return foo (b);
+}
+
+int
+main ()
+{
+  unsigned char x[8] = { 0x01, 0x01, 0x01, 0x01 };
+  if (__CHAR_BIT__ == 8
+      && sizeof (short) == 2
+      && sizeof (int) == 4
+      && bar (x) != 0x8181U)
+    __builtin_abort ();
+  return 0;
+}

        Jakub