From: "H.J. Lu" <hjl.tools@gmail.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>
Cc: Jan Hubicka <hubicka@ucw.cz>
Subject: PING^3: [PATCH] x86: Force __x86_indirect_thunk_reg for function call via GOT
Date: Thu, 15 Mar 2018 15:51:00 -0000 [thread overview]
Message-ID: <CAMe9rOrVW_SyfyXENwGUBfPNWAR3sZmhX3D1dg-4mRirQrL1AA@mail.gmail.com> (raw)
On Sun, Mar 11, 2018 at 7:40 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Mar 5, 2018 at 4:20 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Tue, Feb 27, 2018 at 11:39 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>>> For x86 targets, when -fno-plt is used, external functions are called
>>> via GOT slot, in 64-bit mode:
>>>
>>> [bnd] call/jmp *foo@GOTPCREL(%rip)
>>>
>>> and in 32-bit mode:
>>>
>>> [bnd] call/jmp *foo@GOT[(%reg)]
>>>
>>> With -mindirect-branch=, they are converted to, in 64-bit mode:
>>>
>>> pushq foo@GOTPCREL(%rip)
>>> [bnd] jmp __x86_indirect_thunk[_bnd]
>>>
>>> and in 32-bit mode:
>>>
>>> pushl foo@GOT[(%reg)]
>>> [bnd] jmp __x86_indirect_thunk[_bnd]
>>>
>>> which were incompatible with CFI. In 64-bit mode, since R11 is a scratch
>>> register, we generate:
>>>
>>> movq foo@GOTPCREL(%rip), %r11
>>> [bnd] call/jmp __x86_indirect_thunk_[bnd_]r11
>>>
>>> instead. We do it in ix86_output_indirect_branch so that we can use
>>> the newly proposed R_X86_64_THUNK_GOTPCRELX relocation:
>>>
>>> https://groups.google.com/forum/#!topic/x86-64-abi/eED5lzn3_Mg
>>>
>>> movq foo@OTPCREL_THUNK(%rip), %r11
>>> [bnd] call/jmp __x86_indirect_thunk_[bnd_]r11
>>>
>>> to load GOT slot into R11. If foo is defined locally, linker can can
>>> convert
>>>
>>> movq foo@GOTPCREL_THUNK(%rip), %reg
>>> call/jmp __x86_indirect_thunk_reg
>>>
>>> to
>>>
>>> call/jmp foo
>>> nop 0L(%rax)
>>>
>>> In 32-bit mode, since all caller-saved registers, EAX, EDX and ECX, may
>>> used to function parameters, there is no scratch register available. For
>>> -fno-plt -fno-pic -mindirect-branch=, we expand external function call
>>> to:
>>>
>>> movl foo@GOT, %reg
>>> [bnd] call/jmp *%reg
>>>
>>> so that it can be converted to
>>>
>>> movl foo@GOT, %reg
>>> [bnd] call/jmp __x86_indirect_thunk_[bnd_]reg
>>>
>>> in ix86_output_indirect_branch. Since this is performed during RTL
>>> expansion, other instructions may be inserted between movl and call/jmp.
>>> Linker optimization isn't always possible.
>>>
>>> Tested on i686 and x86-64. OK for trunk?
>>>
>>>
>>> H.J.
>>> ---
>>> gcc/
>>>
>>> PR target/83970
>>> * config/i386/constraints.md (Bs): Allow GOT_memory_operand
>>> for TARGET_LP64 with indirect branch conversion.
>>> (Bw): Likewise.
>>> * config/i386/i386.c (ix86_expand_call): Handle -fno-plt with
>>> -mindirect-branch=.
>>> (ix86_nopic_noplt_attribute_p): Likewise.
>>> (ix86_output_indirect_branch): In 64-bit mode, convert function
>>> call via GOT with R11 as a scratch register using
>>> __x86_indirect_thunk_r11.
>>> (ix86_output_call_insn): In 64-bit mode, set xasm to NULL when
>>> calling ix86_output_indirect_branch with function call via GOT.
>>> * config/i386/i386.md (*call_got_thunk): New call pattern for
>>> TARGET_LP64 with indirect branch conversion.
>>> (*call_value_got_thunk): Likewise.
>>>
>>> gcc/testsuite/
>>>
>>> PR target/83970
>>> * gcc.target/i386/indirect-thunk-5.c: Updated.
>>> * gcc.target/i386/indirect-thunk-6.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-bnd-3.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-bnd-4.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-extern-5.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-extern-6.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-inline-5.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-inline-6.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-13.c: New test.
>>> * gcc.target/i386/indirect-thunk-14.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-bnd-5.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-bnd-6.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-extern-11.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-extern-12.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-inline-8.c: Likewise.
>>> * gcc.target/i386/indirect-thunk-inline-9.c: Likewise.
>>
>> PING:
>>
>> https://gcc.gnu.org/ml/gcc-patches/2018-02/msg01527.html
>>
>
> PING.
>
PING.
--
H.J.
next reply other threads:[~2018-03-15 15:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-15 15:51 H.J. Lu [this message]
2018-03-15 20:51 ` Jan Hubicka
2018-03-15 21:03 ` H.J. Lu
2018-03-15 21:42 ` Jan Hubicka
2018-03-15 22:39 ` H.J. Lu
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