On Sun, Aug 16, 2015 at 12:39 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Sun, Aug 16, 2015 at 12:24 PM, Alexander Monakov <amona...@ispras.ru>
> wrote:
>
>>> + if (!TARGET_64BIT
>>> + || (ix86_cmodel == CM_LARGE_PIC
>>> + && DEFAULT_ABI != MS_ABI))
>>> + {
>>> + use_reg (&use, gen_rtx_REG (Pmode,
>>> + REAL_PIC_OFFSET_TABLE_REGNUM));
>>> + if (ix86_use_pseudo_pic_reg ())
>>> + emit_move_insn (gen_rtx_REG (Pmode,
>>> +
>>> REAL_PIC_OFFSET_TABLE_REGNUM),
>>> + pic_offset_table_rtx);
>>> + }
>>> + }
>>> + else if (!TARGET_PECOFF && !TARGET_MACHO)
>>> + {
>>> + if (TARGET_64BIT)
>>> + {
>>> + fnaddr = gen_rtx_UNSPEC (Pmode,
>>> + gen_rtvec (1, addr),
>>> + UNSPEC_GOTPCREL);
>>> + fnaddr = gen_rtx_CONST (Pmode, fnaddr);
>>> + }
>>> + else
>>> + {
>>> + fnaddr = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, addr),
>>> + UNSPEC_GOT);
>>> + fnaddr = gen_rtx_CONST (Pmode, fnaddr);
>>> + fnaddr = gen_rtx_PLUS (Pmode, pic_offset_table_rtx,
>>> + fnaddr);
>>> + }
>>> + fnaddr = gen_const_mem (Pmode, fnaddr);
>>> + if (GET_MODE (fnaddr) != word_mode)
>>> + fnaddr = gen_rtx_ZERO_EXTEND (word_mode, fnaddr);
>>> + fnaddr = gen_rtx_MEM (QImode, fnaddr);
>>> + }
>>> }
>>> }
>>>
>>> @@ -25686,9 +25715,13 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx
>>> callarg1,
>>> && GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF
>>> && !local_symbolic_operand (XEXP (fnaddr, 0), VOIDmode))
>>> fnaddr = gen_rtx_MEM (QImode, construct_plt_address (XEXP (fnaddr,
>>> 0)));
>>> - else if (sibcall
>>> - ? !sibcall_insn_operand (XEXP (fnaddr, 0), word_mode)
>>> - : !call_insn_operand (XEXP (fnaddr, 0), word_mode))
>>> + else if (!(TARGET_X32
>>> + && MEM_P (fnaddr)
>>> + && GET_CODE (XEXP (fnaddr, 0)) == ZERO_EXTEND
>>> + && GOT_memory_operand (XEXP (XEXP (fnaddr, 0), 0), Pmode))
>>> + && (sibcall
>>> + ? !sibcall_insn_operand (XEXP (fnaddr, 0), word_mode)
>>> + : !call_insn_operand (XEXP (fnaddr, 0), word_mode)))
>>> {
>>> fnaddr = convert_to_mode (word_mode, XEXP (fnaddr, 0), 1);
>>> fnaddr = gen_rtx_MEM (QImode, copy_to_mode_reg (word_mode, fnaddr));
>>
>> Perhaps add a comment that GOT slots are 64-bit on x32?
>>
>
> Good idea. I will update my patch.
>
How about this?
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index bf8a21d..216dee6 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -25690,6 +25690,10 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
fnaddr);
}
fnaddr = gen_const_mem (Pmode, fnaddr);
+ /* Pmode may not be the same as word_mode for x32, which
+ doesn't support indirect branch va 32-bit memory slot.
+ Since x32 GOT slot is 64 bit with zero upper 32 bits,
+ indirect branch via x32 GOT slot is OK. */
if (GET_MODE (fnaddr) != word_mode)
fnaddr = gen_rtx_ZERO_EXTEND (word_mode, fnaddr);
fnaddr = gen_rtx_MEM (QImode, fnaddr);
@@ -25715,7 +25719,9 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
&& GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF
&& !local_symbolic_operand (XEXP (fnaddr, 0), VOIDmode))
fnaddr = gen_rtx_MEM (QImode, construct_plt_address (XEXP (fnaddr, 0)));
- else if (!(TARGET_X32
+ /* Since x32 GOT slot is 64 bit with zero upper 32 bits, indirect
+ branch via x32 GOT slot is OK. */
+ else if (!(Pmode != word_mode
&& MEM_P (fnaddr)
&& GET_CODE (XEXP (fnaddr, 0)) == ZERO_EXTEND
&& GOT_memory_operand (XEXP (XEXP (fnaddr, 0), 0), Pmode))
--
H.J.
