[llvm-dev] [cfe-dev] Is it a va_arg bug in clang?
Shi, Steven via llvm-dev
llvm-dev at lists.llvm.org
Sun Jan 10 01:30:31 PST 2016
Hi Richard,
I tried latest 3.7.1 release, the clang has same build failure and don’t know __builtin_ms_va_list at all. I compared the llvm trunk with 3.7.1 and find the trunk has a VA commit from Davis which is not included in the 3.7.1 release. So, I guess I need to directly build the latest trunk instead of the 3.7.1 release. (why 3.7.1 release doesn’t include this patch?)
commit 7e96f0f6fffbdebfdac238ae76cc3a791acfa23e
Author: Charles Davis <cdavis5x at gmail.com>
Date: Tue Aug 25 23:27:41 2015 +0000
Make variable argument intrinsics behave correctly in a Win64 CC function.
Summary:
This change makes the variable argument intrinsics, `llvm.va_start` and
`llvm.va_copy`, and the `va_arg` instruction behave as they do on Windows
inside a `CallingConv::X86_64_Win64` function. It's needed for a Clang patch
I have to add support for GCC's `__builtin_ms_va_list` constructs.
But when I try to configure the trunk build with cmake, the cmake report failures as below. I can pass configure the 3.7.1 release with the same command. Could you let me know the right configure or build steps for llvm trunk? Appreciate your continues help!
My cmake command:
cmake ../llvm -G "Unix Makefiles" -DCMAKE_BUILD_TYPE="Release" -DLLVM_TARGETS_TO_BUILD="X86" -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_CXX_COMPILER="/usr/bin/g++" -DCMAKE_C_COMPILER="/usr/bin/gcc"
cmake failure output:
… …
-- Performing Test HAS_MAYBE_UNINITIALIZED
-- Performing Test HAS_MAYBE_UNINITIALIZED - Success
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 6: /mnt/disk3/llvmtruck/llvm/au: not foundig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 8: /mnt/disk3/llvmtruck/llvm/au: not foundig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 28: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 29: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 40: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 42: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 54: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 65: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 68: /mnt/disk3/llvmtruck/llvm/a: not foundfig.guess:
/mnt/disk3/llvmtruck/llvm/autoconf/config.guess: 71: /mnt/disk3/llvmtruck/llvm/autoconf/config.guess: Syntax error: word unexpected (expecting "in")
CMake Error at cmake/modules/GetHostTriple.cmake:24 (message):
Failed to execute /mnt/disk3/llvmtruck/llvm/autoconf/config.guess
Call Stack (most recent call first):
cmake/config-ix.cmake:331 (get_host_triple)
CMakeLists.txt:407 (include)
Steven Shi
Intel\SSG\STO\UEFI Firmware
Tel: +86 021-61166522
iNet: 821-6522
From: metafoo at gmail.com [mailto:metafoo at gmail.com] On Behalf Of Richard Smith
Sent: Saturday, January 09, 2016 5:18 PM
To: Shi, Steven
Cc: Clang Dev; llvm-dev
Subject: Re: [cfe-dev] Is it a va_arg bug in clang?
You need a newer version of clang for these builtins.
On Jan 8, 2016 7:15 PM, "Shi, Steven via cfe-dev" <cfe-dev at lists.llvm.org<mailto:cfe-dev at lists.llvm.org>> wrote:
Hi Richard,
Thank you for the info. I build my code in Ubuntu-64bits with simply commands: “clang X64.c”, then run “./a.out” to see the output. If I replace my va_list, va_start, va_arg va_end with __builtin_ms_va_list, __builtin_ms_va_start, __builtin_ms_va_arg, __builtin_ms_va_end, my code will build fail in Ubuntu with below message. Do you suggest I should build it in windows and not in Linux? Or did I miss any build option here? Appreciate if you could let me know the correct build steps.
jshi19 at jshi19-Intel:/mnt/disk3$ clang X64.c
X64.c:12:2: error: unknown type name '__builtin_ms_va_list'; did you mean
'__builtin_va_list'?
__builtin_ms_va_list Marker;
^~~~~~~~~~~~~~~~~~~~
__builtin_va_list
note: '__builtin_va_list' declared here
X64.c:15:2: error: use of unknown builtin '__builtin_ms_va_start'
[-Wimplicit-function-declaration]
__builtin_ms_va_start (Marker, Format);
^
X64.c:17:11: error: use of unknown builtin '__builtin_ms_va_arg'
[-Wimplicit-function-declaration]
Value = __builtin_ms_va_arg (Marker, int);
^
X64.c:17:11: note: did you mean '__builtin_ms_va_start'?
X64.c:15:2: note: '__builtin_ms_va_start' declared here
__builtin_ms_va_start (Marker, Format);
^
X64.c:17:40: error: expected expression
Value = __builtin_ms_va_arg (Marker, int);
^
X64.c:20:2: error: use of unknown builtin '__builtin_ms_va_end'
[-Wimplicit-function-declaration]
__builtin_ms_va_end (Marker);
^
X64.c:20:2: note: did you mean '__builtin_ms_va_arg'?
X64.c:17:11: note: '__builtin_ms_va_arg' declared here
Value = __builtin_ms_va_arg (Marker, int);
^
5 errors generated.
Steven Shi
Intel\SSG\STO\UEFI Firmware
Tel: +86 021-61166522<tel:%2B86%20021-61166522>
iNet: 821-6522
From: metafoo at gmail.com<mailto:metafoo at gmail.com> [mailto:metafoo at gmail.com<mailto:metafoo at gmail.com>] On Behalf Of Richard Smith
Sent: Saturday, January 09, 2016 3:26 AM
To: Shi, Steven
Cc: cfe-dev at lists.llvm.org<mailto:cfe-dev at lists.llvm.org>; llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
Subject: Re: [cfe-dev] Is it a va_arg bug in clang?
On Thu, Jan 7, 2016 at 11:15 PM, Shi, Steven via cfe-dev <cfe-dev at lists.llvm.org<mailto:cfe-dev at lists.llvm.org>> wrote:
For the variadic function error with AMD64 abi and windows calling convention on 64bits x86, I find it has been tracked in Bug 20847 (https://llvm.org/bugs/show_bug.cgi?id=20847) (http://reviews.llvm.org/D1622#inline-9345). Do we still plan to fix it?
You know, I meet exactly same va_arg mistake with llvm3.7 when I enable the Uefi firmware (http://www.uefi.org/) build with clang. The ms_abi is the Uefi firmware binary module standard interface. I really hope this bug fix can been checked in as soon as possible. If we cannot fix it in short time, could we offer a temporary fix patch based on llvm3.7?
This is already fixed in clang trunk. Your code is rejected as follows:
<stdin>:15:17: error: 'va_start' used in Win64 ABI function
va_start (Marker, Format);
^
You need to use __builtin_ms_va_list, __builtin_ms_va_start, __builtin_ms_va_end to use ms_abi varargs semantics. (In particular, note that __builtin_ms_va_list is a different type from va_list, so this can't "just work" in the way you expect it to.)
Steven Shi
Intel\SSG\STO\UEFI Firmware
Tel: +86 021-61166522<tel:%2B86%20021-61166522>
iNet: 821-6522
From: Shi, Steven
Sent: Thursday, January 07, 2016 11:07 PM
To: 'cfe-dev at lists.llvm.org<mailto:cfe-dev at lists.llvm.org>'
Subject: Is it a va_arg bug in clang?
Hello,
I’m trying to use the clang3.7 to compile 64bits x86 code with Microsoft ABI in Ubuntu 64bit, but I find the va_arg get the wrong variable argument from the va_list. Below is my test code.
#include <stdio.h>
#include <stdarg.h>
void
__attribute__((ms_abi))
Foo_va_list (
int VaNum,
const char *Format,
...
)
{
va_list Marker;
long long Value;
va_start (Marker, Format);
for (int i = 0; i < VaNum; i++ ) {
Value = va_arg (Marker, int);
printf("Value = 0x%llx\n", Value);
}
va_end (Marker);
}
int main()
{
Foo_va_list (16, "0123456789abcdef= %x%x%x%x%x%x%x%x%x%x%x%x%x%x%x%x \n", 0,1,2,3,4,5,6,7,8,9,0xa,0xb,0xc,0xd,0xe,0xf);
return 0;
}
The expected output are:
Value = 0x0
Value = 0x1
Value = 0x2
Value = 0x3
Value = 0x4
Value = 0x5
Value = 0x6
Value = 0x7
Value = 0x8
Value = 0x9
Value = 0xa
Value = 0xb
Value = 0xc
Value = 0xd
Value = 0xe
Value = 0xf
But the real output are:
Value = 0x0
Value = 0x1
Value = 0x2
Value = 0x3
Value = 0x4
Value = 0x5
Value = 0x0
Value = 0x1
Value = 0x2
Value = 0x3
Value = 0x4
Value = 0x5
Value = 0x6
Value = 0x7
Value = 0x8
Value = 0x9
After I remove the Microsoft ABI definition __attribute__((ms_abi)) above Foo_va_list () in the code, the output will become correct. I find GCC also have similar wrong behavior with __attribute__((ms_abi)). I don’t know how to make the __attribute__((ms_abi)) work correctly with va_arg. I appreciate if any suggestion.
Steven Shi
Intel\SSG\STO\UEFI Firmware
Tel: +86 021-61166522<tel:%2B86%20021-61166522>
iNet: 821-6522
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