Re: [Xen-devel] [PATCH] x86: fix clang .macro retention check

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Nov 13, 2019 at 06:01:40PM +0100, Jan Beulich wrote:
> There were two problems here: The first closing parentheses got parsed
> by make to end the $(call invocation, and the escaping of the quotes
> wasn't right either, as there's nowhere they would get un-escaped.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> This needs to be tested in an environment where this was actually found
> to matter; I can't see how it can have worked in its former shape. I

Well, I could swear this was working, but obviously I did something
wrong.

> also don't understand why the same commit introducing the check that
> gets fixed here put the .skip check in xen/Rules.mk - the only use of
> .skip that I can spot is in x86 code.

I recall removing some usages of .skip, but TBH I'm not sure whether
ARM was also involved.

I guess it's fine to move it to x86/Rules.mk now, since I also have to
fix an issue with it.

> 
> --- a/Config.mk
> +++ b/Config.mk
> @@ -6,6 +6,8 @@ endif
>  
>  # Convenient variables
>  comma   := ,
> +open    := (
> +close   := )
>  squote  := '
>  #' Balancing squote, to help syntax highlighting
>  empty   :=
> --- a/xen/arch/x86/Rules.mk
> +++ b/xen/arch/x86/Rules.mk
> @@ -82,6 +64,6 @@ $(call as-option-add,CFLAGS,CC,".include
>  # Check whether clang keeps .macro-s between asm()-s:
>  # https://bugs.llvm.org/show_bug.cgi?id=36110
>  $(call as-option-add,CFLAGS,CC,\
> -                     ".macro FOO\n.endm\"); asm volatile (\".macro 
> FOO\n.endm",\
> +                     ".macro FOO\n.endm"$$(close); asm volatile 
> $$(open)".macro FOO\n.endm",\

Thanks, while here could you also replace the '\n' with a ';'? '\n'
doesn't work properly and gives me the following error:

<stdin>:1:32: error: missing terminating '"' character 
[-Werror,-Winvalid-pp-token]
void _(void) { asm volatile (  ".macro FOO
                               ^
<stdin>:1:32: error: expected string literal in 'asm'
<stdin>:3:6: error: missing terminating '"' character 
[-Werror,-Winvalid-pp-token]
.endm" ); }
     ^
<stdin>:3:12: error: expected ')'
.endm" ); }
           ^
<stdin>:1:29: note: to match this '('
void _(void) { asm volatile (  ".macro FOO
                            ^
<stdin>:3:12: error: expected '}'
.endm" ); }
           ^
<stdin>:1:14: note: to match this '{'
void _(void) { asm volatile (  ".macro FOO
             ^

Roger.

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