RFR: 8284437: Building from different users/workspace is not always deterministic [v2]

[Andrew Leonard]

On Fri, 8 Apr 2022 14:18:50 GMT, Maxim Kartashev <duke at openjdk.java.net> wrote:

>> @magicus 
>>> Is it possible to pass the ".file" directive on the command line?
>> 
>> I don't think so. Your other idea works quite well, though. If you have this in the source
>> 
>>        .file THIS_FILE
>> 
>> and you specify this on the command line
>> 
>> -DTHIS_FILE='"src/hotspot/os_cpu/linux_x86/linux_x86_64.S"'
>> 
>> you get the same reproducible and debuggable result.
>
>> @mkartashev Why don't you try building with clang as two different users, in two different directories, and see if the build is non-reproducible without this patch, but is reproducible with it (incl. your suggested change to include clang as well)?
> 
> I'm going to do this on Mac, but perhaps not in the immediate future. If someone has the time for this right now, please jump ahead of me in the line.

@mkartashev yes you're right, here's the dwarf for the compilation unit that I changed to add the .file to:

COMPILE_UNIT<header overall offset = 0x00c0e8d7>:
< 0><0x0000000b>  DW_TAG_compile_unit
                    DW_AT_stmt_list             0x0022146d
                    DW_AT_low_pc                0x004707c0
                    DW_AT_high_pc               0x00470a40
                    DW_AT_name                  atomic_linux_aarch64.S
                    DW_AT_comp_dir              make/hotspot
                    DW_AT_producer              GNU AS 2.27
                    DW_AT_language              DW_LANG_Mips_Assembler


So it needs the full source path specifying as you said. Note however -debug-prefix-map has affected the DW_AT_comp_dir, removing the absolute workspace folder.

Note, previously this is what the same entry had:

COMPILE_UNIT<header overall offset = 0x00c0e8d7>:
< 0><0x0000000b>  DW_TAG_compile_unit
                    DW_AT_stmt_list             0x00224f82
                    DW_AT_low_pc                0x004707c0
                    DW_AT_high_pc               0x00470a40
                    DW_AT_name                  /home/andrew2/jdk/src/hotspot/os_cpu/linux_aarch64/atomic_linux_aarch64.S
                    DW_AT_comp_dir              /home/andrew2/jdk/make/hotspot
                    DW_AT_producer              GNU AS 2.27
                    DW_AT_language              DW_LANG_Mips_Assembler



So I am thinking adding a .file directive to the .S file specifying the "full source path" should do the trick thanks to -debug-prefix-map, I will do a test..

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PR: https://git.openjdk.java.net/jdk/pull/8124