Re: [Xen-devel] [Makefile] asm: handle comments when creating header file

["Tautschnig, Michael" <tautschn@xxxxxxxxxxxx>]

Jan, All,

> On 10 Jan 2018, at 16:02, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> 
>>>> On 10.01.18 at 16:14, <nmanthey@xxxxxxxxxx> wrote:
>> In the early steps of compilation, the asm header files are created, such
>> as include/asm-$(TARGET_ARCH)/asm-offsets.h. These files depend on the
>> assembly file arch/$(TARGET_ARCH)/asm-offsets.s, which is generated
>> before. Depending on the used assembler, there might be comments in the
>> assembly files.
>> 
>> This commit adds handling comments in the assembler during the creation of
>> the asm header files.
> 
> I have a hard time seeing how ...
> 
>> --- a/xen/Makefile
>> +++ b/xen/Makefile
>> @@ -189,7 +189,7 @@ include/asm-$(TARGET_ARCH)/asm-offsets.h: 
>> arch/$(TARGET_ARCH)/asm-offsets.s
>>        echo "#ifndef __ASM_OFFSETS_H__"; \
>>        echo "#define __ASM_OFFSETS_H__"; \
>>        echo ""; \
>> -      sed -rne "/==>/{s:.*==>(.*)<==.*:\1:; s: [\$$#]: :; p;}"; \
> 
> ... this pattern could match any comment that we currently have.
> Would you mind clarifying what it is that is actually broken (and
> hence wants/needs fixing)?
> 

Re-adding the new line:

+         sed -rne "/^[^#].*==>/{s:.*==>(.*)<==.*:\1:; s: [\$$#]: :; p;}"; \

The change "handles comments" by not printing those to the generated header
file, where they would confuse the preprocessor (as "#" starts comments at
the assembler level). It seems perfectly ok if this matches any existing
comments as none such should get printed to the header file.

The problems showed up when using goto-gcc (a compiler for subsequent use of
static analysis tooling), which embeds additional information in the comments.

Hope this helps,
Michael





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