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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>gcc as of 4.2.4 generates the debuginfo even with “.file” (as did clang 6.0.0). I’ll check a modern gcc.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> David Blaikie <dblaikie@gmail.com> <br><b>Sent:</b> Friday, August 24, 2018 11:10 AM<br><b>To:</b> paul.robinson@sony.com<br><b>Cc:</b> bcain@codeaurora.org; llvm-dev@lists.llvm.org<br><b>Subject:</b> Re: [llvm-dev] [assembler + debuginfo] interaction with .file directive and debuginfo<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>What does gcc do?<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Fri, Aug 24, 2018 at 9:05 AM via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>There are two forms of the .file directive. One is simply</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> .file "path"</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>and the other is</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> .file <file-number> [ "dir"] "path" [ …. other stuff ]</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>The latter is sometimes referred to as the "DWARF" form of the .file directive. I don't know the history about the different forms. I have certainly messed with the latter form to accommodate the needs of DWARF v5.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>I think it's pretty certain that the DWARF form of .file means that the .s file was generated with debug info, and therefore the correct behavior of "clang –g foo.s" in that case is to ignore the –g and assume the assembler source has all the right stuff.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>If the older form of .file can mean nothing more than "emit a file symbol" and not imply that the assembler source file itself already contains debug info, then seeing that form should not cause the assembler to ignore –g. But as I said, I don't know the history and I don't understand how the first form is generally used.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>I'm quite willing to believe I did not understand the (largely unstated) specification for the non-DWARF form of .file, and if others agree that it should not imply that debug info already exists, then reporting that as a bug is appropriate. I can't say I'd be able to find time to try to *fix* it before October, as I'm already over-committed, but I'd anticipate getting to it around that time.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#1F497D'>--paulr</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><a name="m_1784710761661091587__MailEndCompose"><span style='color:#1F497D'> </span></a><o:p></o:p></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span style='font-size:10.0pt;font-family:"Tahoma",sans-serif'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma",sans-serif'> <a href="mailto:bcain@codeaurora.org" target="_blank">bcain@codeaurora.org</a> [mailto:<a href="mailto:bcain@codeaurora.org" target="_blank">bcain@codeaurora.org</a>] <br><b>Sent:</b> Thursday, August 23, 2018 3:18 PM<br><b>To:</b> <a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br><b>Cc:</b> Robinson, Paul<br><b>Subject:</b> [assembler + debuginfo] interaction with .file directive and debuginfo </span><o:p></o:p></p></div></div></div></div></div><div><div><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>[ I discussed this briefly with Paul off list and he suggested it would be better here. ]<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Among the changes in 7.0.0 are some that were added to support DWARFv5’s .debug_line. <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>The presence of “.file” mutes debug info generated by the assembler as of r328208 – logic in AsmParser::enabledGenDwarfForAssembly().<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>The comment there states: “If we haven't encountered any .file directives (which would imply that the assembler source was produced with debug info already) then emit one describing the assembler source file itself.”<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Does .file imply that the assembly source was already produced with debug info? Perhaps not in all cases. If you wanted to emit an ELF::STT_FILE into your object, for example, you might add ```.file "foo.s"```.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I think we should change this behavior to the previous – check for “-g” but ignore “.file” directives. Or maybe there’s a compromise to be found among the different versions of “.file” with various args? Thoughts?<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>-Brian<o:p></o:p></p></div></div></div><p class=MsoNormal>_______________________________________________<br>LLVM Developers mailing list<br><a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></p></blockquote></div></div></div></body></html>