On Wed, 22 Mar 2023, LIU Hao wrote:
This is the first attempt to allow the CRT to be built with `-masm=intel`.
This patch itself may look messy because it contains a lot of inline changes.
It should be examined with `git show --color-words='\S'`.
I have only verified that the CRT actually builds with
{i686,x86_64}-w64-mingw32-gcc; not sure whether anything goes wrong. Martin,
would you please include this patch in your nightly tests? `-masm=intel`
requires the latest Clang, though. Older versions do not accept Intel syntax
in inline assembly (but they do output Intel syntax).
Out of curiosity, do you have a reference to when it got this new support?
(16.0.0 was just released a few days ago.) Anyway, I'll test with the very
latest from git.
The patch successfully builds with Clang for x86_64 in the default (AT&T)
mode for x86_64, but it breaks compilation for i686, where I get this:
<inline asm>:4:6: error: brackets expression not supported on this target
jmp [__imp___scprintf]
^
1 error generated.
Looking at the change, I see that you're trying to use __REGISTER_PREFIX__
to disambiguate between the two modes - but as far as I can see,
__REGISTER_PREFIX__ expands to an empty string in both GCC and Clang, for
both i686 and x86_64, when running in the default AT&T mode. So I don't
really see how that mode detection is meant to work?
(The same issue also affects the change in __guard_dispatch_icall_dummy,
but it's not immediately appear as a build error when building
mingw-w64-crt on its own.)
If building with -masm=intel (I configured by adding CFLAGS="-g -O2
-masm=intel" to the configure line), I'm getting lots of build errors
though:
x86_64-w64-mingw32/include/psdk_inc/intrin-impl.h:811:1:
error: unknown token in expression
__buildreadseg(__readgsbyte, unsigned char, "gs", "b")
^
include/psdk_inc/intrin-impl.h:222:14:
note: expanded from macro '__buildreadseg'
__asm__ ("mov{" a " %%" z ":%[offset], %[ret] | %[ret], %%" z
":%[offset]}" \
^
<inline asm>:2:10: note: instantiated into assembly here
mov al, %gs:[rax]
^
../profile/mcountFunc.S:41:7: error: unknown token in expression
push %rbp
^
../math/llrint.c:13:25: error: ambiguous operand size for instruction
'fistp'
__asm__ __volatile__ ("fistp{ll} %0" : "=m" (retval) : "t" (x) : "st");
^
<inline asm>:2:8: note: instantiated into assembly here
fistp [rsp]
^~~~~
../stdio/scanf.S:48:11: error: unknown token in expression
pushq %rbp
^
../math/x86/_chgsignl.S:32:8: error: unknown token in expression
movq (%rdx), %rax
^
../math/x86/acosf.c:20:13: error: unknown token in expression
"fld %%st\n\t"
^
<inline asm>:2:6: note: instantiated into assembly here
fld %st
^
../math/x86/exp.def.h:87:71: error: ambiguous operand size for instruction
'fld'
"{ fldt %2 | fld %2 }\n\t"
/* 4 c0 */
^
<inline asm>:16:7: note: instantiated into assembly here
fld [rip + offset c0]
^~~~~~~~~~~~~~~~~
(Plus lots, lots more - I just tried to pick up examples of each class of
issues that I saw.)
// Martin
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