On November 18, 2014 10:59:28 PM CET, Jakub Jelinek <ja...@redhat.com> wrote:
>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?
OK.
Thanks,
Richard.
>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
