On Mon, Mar 5, 2012 at 4:53 AM, H.J. Lu <hjl.to...@gmail.com> wrote:

> and compiler does generate the same output. i386.c also has
>        xasm = "jmp\t%A0";
>    xasm = "call\t%A0";
> for calls.  There are no separate indirect call patterns.  For x32,
> only indirect register calls have to be in DImode.  The direct call
> should be in Pmode (SImode).

Direct call just expects label to some abolute address that is assumed
to fit in 32 bits (see constant_call_address_operand_p).

call and jmp insn expect word_mode operands, so please change
ix86_expand_call and call patterns in the same way as jump
instructions above.

> Since x86-64 hardware always zero-extends upper 32bits of 64bit
> registers when loading its lower 32bits, it is safe and easier to just
> to output 64bit registers for %A than zero-extend it by hand for all
> jump/call patterns.

No, the instruction expects word_mode operands, so we have to extend
values to expected mode. I don't think that patching at insn output
time is acceptable.

BTW: I propose to split the patch into smaller pieces, dealing with
various independent parts separately. Handling jump/call insn is
definitely one of them, the other is stringops handling, another
prologue/epilogue expansion.


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