On Mon, Jan 20, 2014 at 9:38 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> As mentioned in the PR or even in the comment below, ix86_decompose_address
> sometimes sets parts.base to some REG and parts.disp to const0_rtx, even
> when the operands aren't of a lea insn, but normal or zero extending mov.
>
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?
>
> 2014-01-20 Jakub Jelinek <ja...@redhat.com>
>
> PR target/59880
> * config/i386/i386.c (ix86_avoid_lea_for_addr): Return false
> if operands[1] is a REG or ZERO_EXTEND of a REG.
>
> * gcc.target/i386/pr59880.c: New test.
> --- gcc/config/i386/i386.c.jj 2014-01-19 12:18:49.000000000 +0100
> +++ gcc/config/i386/i386.c 2014-01-19 19:02:34.078168289 +0100
> @@ -18159,8 +18159,19 @@ ix86_avoid_lea_for_addr (rtx insn, rtx o
> if (!TARGET_AVOID_LEA_FOR_ADDR || optimize_function_for_size_p (cfun))
> return false;
>
> + /* The "at least two components" test below might not catch simple
> + *mov[sd]i_internal or *zero_extendsidi2 insns if parts.base is
> + non-NULL and parts.disp is const0_rtx as the only components in
> + the address, e.g. if the register is %rbp or %r13. As this
> + test is much cheaper and moves or zero extensions are the common
> + case, do this check first. */
> + if (REG_P (operands[1])
> + || (GET_CODE (operands[1]) == ZERO_EXTEND
> + && REG_P (XEXP (operands[1], 0))))
> + return false;
> +
> /* Check it is correct to split here. */
> - if (!ix86_ok_to_clobber_flags(insn))
> + if (!ix86_ok_to_clobber_flags (insn))
> return false;
>
> ok = ix86_decompose_address (operands[1], &parts);
> --- gcc/testsuite/gcc.target/i386/pr59880.c.jj 2014-01-19 19:24:44.094382629
> +0100
> +++ gcc/testsuite/gcc.target/i386/pr59880.c 2014-01-19 19:25:30.000000000
> +0100
> @@ -0,0 +1,14 @@
> +/* PR target/59880 */
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mtune=silvermont" } */
> +
> +register unsigned int r13 __asm ("r13");
> +unsigned long long
> +foo (void)
> +{
> + return r13;
> +}
> +
> +/* Ensure we don't emit a useless zero-extension after another
> + zero-extension. */
> +/* { dg-final { scan-assembler-not "%eax, %eax" } } */
>
> Jakub
This is OK for mainline, I will take care for a backport (together
with 59379) to other release branches.
Thanks,
Uros.
