Alexey Samsonov
2013-Apr-16 09:37 UTC
[LLVMdev] RFC: Using zlib to decompress debug info sections.
Hi! TL;DR WDYT of adding zlib decompression capabilities to LLVMObject library? ld.gold from GNU binutils has --compress-debug-sections=zlib option, which uses zlib to compress .debug_xxx sections and renames them to .zdebug_xxx. binutils (and GDB) support this properly, while LLVM command line tools don't: $ ld --version GNU gold (GNU Binutils for Ubuntu 2.22) 1.11 $ ./bin/clang++ -g a.cc -Wl,--compress-debug-sections=zlib $ objdump -h a.out | grep debug 26 .debug_info 00000066 0000000000000000 0000000000000000 00002010 2**0 27 .debug_abbrev 00000048 0000000000000000 0000000000000000 00002068 2**0 28 .debug_aranges 00000000 0000000000000000 0000000000000000 000020bb 2**0 29 .debug_macinfo 00000000 0000000000000000 0000000000000000 000020cf 2**0 30 .debug_line 00000053 0000000000000000 0000000000000000 000020e3 2**0 31 .debug_loc 00000000 0000000000000000 0000000000000000 0000213e 2**0 32 .debug_pubtypes 00000000 0000000000000000 0000000000000000 00002152 2**0 33 .debug_str 00000069 0000000000000000 0000000000000000 00002166 2**0 34 .debug_ranges 00000000 0000000000000000 0000000000000000 000021d9 2**0 $ ./bin/llvm-objdump -h a.out | grep debug 27 .zdebug_info 00000058 0000000000000000 28 .zdebug_abbrev 00000053 0000000000000000 29 .zdebug_aranges 00000014 0000000000000000 30 .zdebug_macinfo 00000014 0000000000000000 31 .zdebug_line 0000005b 0000000000000000 32 .zdebug_loc 00000014 0000000000000000 33 .zdebug_pubtypes 00000014 0000000000000000 34 .zdebug_str 00000073 0000000000000000 35 .zdebug_ranges 00000014 0000000000000000 Decompression and proper handling of debug info sections may be needed in llvm-dwarfdump and llvm-symbolizer tools. We can implement this by: 1) Checking if zlib is present in the system during configuration. 2) Adding zlib decompression to llvm::MemoryBuffer, and section decompression to LLVMObject (this would require optional linking with -lz). 3) Using the methods in LLVM tools where needed. Does this make sense to you? -- Alexey Samsonov, MSK -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130416/28638099/attachment.html>
Nick Lewycky
2013-Apr-16 09:47 UTC
[LLVMdev] RFC: Using zlib to decompress debug info sections.
On 04/16/2013 02:37 AM, Alexey Samsonov wrote:> Hi! > > TL;DR WDYT of adding zlib decompression capabilities to LLVMObject library?Yes, I want this.> ld.gold from GNU binutils has --compress-debug-sections=zlib option, > which uses zlib to compress .debug_xxx sections and renames them to > .zdebug_xxx. > binutils (and GDB) support this properly, while LLVM command line tools > don't: > > $ ld --version > GNU gold (GNU Binutils for Ubuntu 2.22) 1.11 > $ ./bin/clang++ -g a.cc -Wl,--compress-debug-sections=zlib > $ objdump -h a.out | grep debug > 26 .debug_info 00000066 0000000000000000 0000000000000000 > 00002010 2**0 > 27 .debug_abbrev 00000048 0000000000000000 0000000000000000 > 00002068 2**0 > 28 .debug_aranges 00000000 0000000000000000 0000000000000000 > 000020bb 2**0 > 29 .debug_macinfo 00000000 0000000000000000 0000000000000000 > 000020cf 2**0 > 30 .debug_line 00000053 0000000000000000 0000000000000000 > 000020e3 2**0 > 31 .debug_loc 00000000 0000000000000000 0000000000000000 > 0000213e 2**0 > 32 .debug_pubtypes 00000000 0000000000000000 0000000000000000 > 00002152 2**0 > 33 .debug_str 00000069 0000000000000000 0000000000000000 > 00002166 2**0 > 34 .debug_ranges 00000000 0000000000000000 0000000000000000 > 000021d9 2**0 > $ ./bin/llvm-objdump -h a.out | grep debug > 27 .zdebug_info 00000058 0000000000000000 > 28 .zdebug_abbrev 00000053 0000000000000000 > 29 .zdebug_aranges 00000014 0000000000000000 > 30 .zdebug_macinfo 00000014 0000000000000000 > 31 .zdebug_line 0000005b 0000000000000000 > 32 .zdebug_loc 00000014 0000000000000000 > 33 .zdebug_pubtypes 00000014 0000000000000000 > 34 .zdebug_str 00000073 0000000000000000 > 35 .zdebug_ranges 00000014 0000000000000000 > > Decompression and proper handling of debug info sections may be needed > in llvm-dwarfdump and llvm-symbolizer tools. We can implement this by: > 1) Checking if zlib is present in the system during configuration. > 2) Adding zlib decompression to llvm::MemoryBuffer, and section > decompression to LLVMObject (this would require optional linking with -lz). > 3) Using the methods in LLVM tools where needed. > > Does this make sense to you?Yes, exactly. I'm not certain that MemoryBuffer and LLVMObject are the right places, but it doesn't sound wrong. Nick
Michael Spencer
2013-Apr-16 16:31 UTC
[LLVMdev] RFC: Using zlib to decompress debug info sections.
On Tue, Apr 16, 2013 at 2:37 AM, Alexey Samsonov <samsonov at google.com>wrote:> Hi! > > TL;DR WDYT of adding zlib decompression capabilities to LLVMObject library? >> ld.gold from GNU binutils has --compress-debug-sections=zlib option, > which uses zlib to compress .debug_xxx sections and renames them to > .zdebug_xxx. > binutils (and GDB) support this properly, while LLVM command line tools > don't: > > $ ld --version > GNU gold (GNU Binutils for Ubuntu 2.22) 1.11 > $ ./bin/clang++ -g a.cc -Wl,--compress-debug-sections=zlib > $ objdump -h a.out | grep debug > 26 .debug_info 00000066 0000000000000000 0000000000000000 00002010 > 2**0 > 27 .debug_abbrev 00000048 0000000000000000 0000000000000000 00002068 > 2**0 > 28 .debug_aranges 00000000 0000000000000000 0000000000000000 000020bb > 2**0 > 29 .debug_macinfo 00000000 0000000000000000 0000000000000000 000020cf > 2**0 > 30 .debug_line 00000053 0000000000000000 0000000000000000 000020e3 > 2**0 > 31 .debug_loc 00000000 0000000000000000 0000000000000000 0000213e > 2**0 > 32 .debug_pubtypes 00000000 0000000000000000 0000000000000000 00002152 > 2**0 > 33 .debug_str 00000069 0000000000000000 0000000000000000 00002166 > 2**0 > 34 .debug_ranges 00000000 0000000000000000 0000000000000000 000021d9 > 2**0 > $ ./bin/llvm-objdump -h a.out | grep debug > 27 .zdebug_info 00000058 0000000000000000 > 28 .zdebug_abbrev 00000053 0000000000000000 > 29 .zdebug_aranges 00000014 0000000000000000 > 30 .zdebug_macinfo 00000014 0000000000000000 > 31 .zdebug_line 0000005b 0000000000000000 > 32 .zdebug_loc 00000014 0000000000000000 > 33 .zdebug_pubtypes 00000014 0000000000000000 > 34 .zdebug_str 00000073 0000000000000000 > 35 .zdebug_ranges 00000014 0000000000000000 > > Decompression and proper handling of debug info sections may be needed > in llvm-dwarfdump and llvm-symbolizer tools. We can implement this by: > 1) Checking if zlib is present in the system during configuration. > 2) Adding zlib decompression to llvm::MemoryBuffer, and section > decompression to LLVMObject (this would require optional linking with -lz). > 3) Using the methods in LLVM tools where needed. > > Does this make sense to you? > > -- > Alexey Samsonov, MSK >I'm not sure MemoryBuffer is the right place to do this either. I'm also not sure if we want debug info decompression to be transparent in LLVMObject or not. I'm leaning towards no since it's not part of the standard yet, unless gold is actually using the SHF_COMPRESSED flag. I think it should be part of Object, but as an external API that is used when you find a section you know from external factors (the name matches some list) is compressed. - Michael Spencer -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130416/31b18535/attachment.html>
Alexey Samsonov
2013-Apr-16 16:37 UTC
[LLVMdev] RFC: Using zlib to decompress debug info sections.
On Tue, Apr 16, 2013 at 8:31 PM, Michael Spencer <bigcheesegs at gmail.com>wrote:> On Tue, Apr 16, 2013 at 2:37 AM, Alexey Samsonov <samsonov at google.com>wrote: > >> Hi! >> >> TL;DR WDYT of adding zlib decompression capabilities to LLVMObject >> library? >> > >> ld.gold from GNU binutils has --compress-debug-sections=zlib option, >> which uses zlib to compress .debug_xxx sections and renames them to >> .zdebug_xxx. >> binutils (and GDB) support this properly, while LLVM command line tools >> don't: >> >> $ ld --version >> GNU gold (GNU Binutils for Ubuntu 2.22) 1.11 >> $ ./bin/clang++ -g a.cc -Wl,--compress-debug-sections=zlib >> $ objdump -h a.out | grep debug >> 26 .debug_info 00000066 0000000000000000 0000000000000000 00002010 >> 2**0 >> 27 .debug_abbrev 00000048 0000000000000000 0000000000000000 00002068 >> 2**0 >> 28 .debug_aranges 00000000 0000000000000000 0000000000000000 000020bb >> 2**0 >> 29 .debug_macinfo 00000000 0000000000000000 0000000000000000 000020cf >> 2**0 >> 30 .debug_line 00000053 0000000000000000 0000000000000000 000020e3 >> 2**0 >> 31 .debug_loc 00000000 0000000000000000 0000000000000000 0000213e >> 2**0 >> 32 .debug_pubtypes 00000000 0000000000000000 0000000000000000 >> 00002152 2**0 >> 33 .debug_str 00000069 0000000000000000 0000000000000000 00002166 >> 2**0 >> 34 .debug_ranges 00000000 0000000000000000 0000000000000000 000021d9 >> 2**0 >> $ ./bin/llvm-objdump -h a.out | grep debug >> 27 .zdebug_info 00000058 0000000000000000 >> 28 .zdebug_abbrev 00000053 0000000000000000 >> 29 .zdebug_aranges 00000014 0000000000000000 >> 30 .zdebug_macinfo 00000014 0000000000000000 >> 31 .zdebug_line 0000005b 0000000000000000 >> 32 .zdebug_loc 00000014 0000000000000000 >> 33 .zdebug_pubtypes 00000014 0000000000000000 >> 34 .zdebug_str 00000073 0000000000000000 >> 35 .zdebug_ranges 00000014 0000000000000000 >> >> Decompression and proper handling of debug info sections may be needed >> in llvm-dwarfdump and llvm-symbolizer tools. We can implement this by: >> 1) Checking if zlib is present in the system during configuration. >> 2) Adding zlib decompression to llvm::MemoryBuffer, and section >> decompression to LLVMObject (this would require optional linking with -lz). >> 3) Using the methods in LLVM tools where needed. >> >> Does this make sense to you? >> >> -- >> Alexey Samsonov, MSK >> > > I'm not sure MemoryBuffer is the right place to do this either. I'm also > not sure if we want debug info decompression to be transparent in > LLVMObject or not. I'm leaning towards no since it's not part of the > standard yet, >Yeah, I also think that decompression should be explicitly requested by the user of LLVMObject.> unless gold is actually using the SHF_COMPRESSED flag. >> I think it should be part of Object, but as an external API that is used > when you find a section you know from external factors (the name matches > some list) is compressed. > > - Michael Spencer > >-- Alexey Samsonov, MSK -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130416/db863f0a/attachment.html>
Maybe Matching Threads
- [LLVMdev] RFC: Using zlib to decompress debug info sections.
- [LLVMdev] RFC: Using zlib to decompress debug info sections.
- [LLVMdev] RFC: Using zlib to decompress debug info sections.
- [LLVMdev] RFC: Using zlib to decompress debug info sections.
- [LLVMdev] RFC: Using zlib to decompress debug info sections.