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<p class="MsoNormal">FTR, the absence of an attribute from a list in Appendix A does not mean it’s forbidden; just that it’s not usual.<o:p></o:p></p>
<p class="MsoNormal">The argument that neither gdb nor lldb look for it is more compelling, as well as observing that the flag was invariably zero.<o:p></o:p></p>
<p class="MsoNormal">(I have no objection to its removal.)<o:p></o:p></p>
<p class="MsoNormal">--paulr<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> Fāng-ruì Sòng <maskray@google.com> <br>
<b>Sent:</b> Tuesday, May 26, 2020 5:53 PM<br>
<b>To:</b> David Blaikie <dblaikie@gmail.com><br>
<b>Cc:</b> Fangrui Song <llvmlistbot@llvm.org>; Robinson, Paul <paul.robinson@sony.com>; llvm-commits <llvm-commits@lists.llvm.org>; Adrian Prantl <aprantl@apple.com><br>
<b>Subject:</b> Re: [llvm] 20e9fc5 - [MCDwarf] Delete unneeded DW_AT_prototyped for DW_TAG_label<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">DWARF v5 Appendix A. Attributes by Tag (Informative) does not say DW_AT_prototyped is applicable for DW_TAG_label.<o:p></o:p></p>
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<p class="MsoNormal">I have checked that neither gdb nor lldb reads DW_AT_prototyped.<o:p></o:p></p>
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<p class="MsoNormal">So I deleted DW_AT_prototyped.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">(I have also checked GNU as' behavior: it generates a single DW_TAG_compile_unit, There is no DW_TAG_label. However, I guess there might be some low value having DW_TAG_label.)<o:p></o:p></p>
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<p class="MsoNormal">On Tue, May 26, 2020 at 2:28 PM Adrian Prantl <<a href="mailto:aprantl@apple.com">aprantl@apple.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">I think I replied a little too early. This *is* MCDwarf.cpp so my comment doesn't really add any new information.<o:p></o:p></p>
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<p class="MsoNormal">To actually contribute something useful, it looks like your hunch was correct:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif;color:#AAAB25">commit f7d77069ca47cab8f629e1cbe71265f035281329<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif">Author: Kevin Enderby <<a href="mailto:enderby@apple.com" target="_blank">enderby@apple.com</a>><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif">Date: Tue Jan 10 21:12:34 2012 +0000<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif"> This is the matching change for the data structure name changes for the<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif"> functional change in r147860 to use DW_TAG_<span style="color:white;background:black">label</span>'s instead TAG_subprogram's.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif"> This only changes names and updates comments. No functional change.<o:p></o:p></span></p>
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<p style="margin:0in;margin-bottom:.0001pt;font-stretch:normal;min-height:16px"><span style="font-family:"Menlo",serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Menlo",serif"> llvm-svn: 147877<o:p></o:p></span></p>
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<p class="MsoNormal">On May 26, 2020, at 2:09 PM, David Blaikie <<a href="mailto:dblaikie@gmail.com" target="_blank">dblaikie@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">On Tue, May 26, 2020 at 2:02 PM Adrian Prantl <<a href="mailto:aprantl@apple.com" target="_blank">aprantl@apple.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Prior to the patch that added DW_TAG_label for C labels inside of functions, I have only seen DW_TAG_label inside object files compiled from assembler. I guess there that makes the same amount of sense (though I probably would have left
it unspecified).<o:p></o:p></p>
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<p class="MsoNormal">Not sure I follow your comment, sorry - could you rephrase/describe your perspective in more detail?<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">-- adrian<o:p></o:p></p>
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<p class="MsoNormal">On May 26, 2020, at 1:57 PM, David Blaikie <<a href="mailto:dblaikie@gmail.com" target="_blank">dblaikie@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Any sense of the history of this? I'm guessing at some point these were emitted as subprograms rather than labels, and as subprograms it made sense to include teh prototyped=false attribute? <o:p></o:p></p>
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<p class="MsoNormal">On Mon, May 25, 2020 at 3:00 PM Fangrui Song via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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Author: Fangrui Song<br>
Date: 2020-05-24T22:24:24-07:00<br>
New Revision: 20e9fc55feb58dd1f766a494c530684011291ff3<br>
<br>
URL: <a href="https://urldefense.com/v3/__https:/github.com/llvm/llvm-project/commit/20e9fc55feb58dd1f766a494c530684011291ff3__;!!JmoZiZGBv3RvKRSx!oFY6rn6q7NLaL_YAxDThAs3yQWxPJ2yZAjofKkDP62ej1h-xh78EGsykA1fF5ewvZQ$" target="_blank">
https://github.com/llvm/llvm-project/commit/20e9fc55feb58dd1f766a494c530684011291ff3</a><br>
DIFF: <a href="https://urldefense.com/v3/__https:/github.com/llvm/llvm-project/commit/20e9fc55feb58dd1f766a494c530684011291ff3.diff__;!!JmoZiZGBv3RvKRSx!oFY6rn6q7NLaL_YAxDThAs3yQWxPJ2yZAjofKkDP62ej1h-xh78EGsykA1d1z55HUg$" target="_blank">
https://github.com/llvm/llvm-project/commit/20e9fc55feb58dd1f766a494c530684011291ff3.diff</a><br>
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LOG: [MCDwarf] Delete unneeded DW_AT_prototyped for DW_TAG_label<br>
<br>
Added: <br>
<br>
<br>
Modified: <br>
llvm/lib/MC/MCDwarf.cpp<br>
llvm/test/MC/MachO/gen-dwarf.s<br>
<br>
Removed: <br>
<br>
<br>
<br>
################################################################################<br>
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp<br>
index 0b7fc4554018..71b8f0e28e1c 100644<br>
--- a/llvm/lib/MC/MCDwarf.cpp<br>
+++ b/llvm/lib/MC/MCDwarf.cpp<br>
@@ -846,7 +846,6 @@ static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {<br>
EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);<br>
EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);<br>
EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);<br>
- EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);<br>
EmitAbbrev(MCOS, 0, 0);<br>
<br>
// DW_TAG_unspecified_parameters DIE abbrev (3).<br>
@@ -1087,9 +1086,6 @@ static void EmitGenDwarfInfo(MCStreamer *MCOS,<br>
MCSymbolRefExpr::VK_None, context);<br>
MCOS->emitValue(AT_low_pc, AddrSize);<br>
<br>
- // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.<br>
- MCOS->emitInt8(0);<br>
-<br>
// The DW_TAG_unspecified_parameters DIE abbrev (3).<br>
MCOS->emitULEB128IntValue(3);<br>
<br>
<br>
diff --git a/llvm/test/MC/MachO/gen-dwarf.s b/llvm/test/MC/MachO/gen-dwarf.s<br>
index 6d39d278e818..58f8a7ccf899 100644<br>
--- a/llvm/test/MC/MachO/gen-dwarf.s<br>
+++ b/llvm/test/MC/MachO/gen-dwarf.s<br>
@@ -30,7 +30,6 @@ _x: .long 1<br>
// CHECK: DW_AT_decl_file DW_FORM_data4<br>
// CHECK: DW_AT_decl_line DW_FORM_data4<br>
// CHECK: DW_AT_low_pc DW_FORM_addr<br>
-// CHECK: DW_AT_prototyped DW_FORM_flag<br>
<br>
// CHECK: [3] DW_TAG_unspecified_parameters DW_CHILDREN_no<br>
<br>
@@ -53,7 +52,6 @@ _x: .long 1<br>
// CHECK: DW_AT_decl_file ([[FILE:%22.*gen-dwarf.s%22]])<br>
// CHECK: DW_AT_decl_line (5)<br>
// CHECK: DW_AT_low_pc (0x0000000000000000)<br>
-// CHECK: DW_AT_prototyped (0x00)<br>
<br>
// CHECK: DW_TAG_unspecified_parameters<br>
<br>
@@ -64,7 +62,6 @@ _x: .long 1<br>
// CHECK: DW_AT_decl_file ([[FILE]])<br>
// CHECK: DW_AT_decl_line (9)<br>
// CHECK: DW_AT_low_pc (0x0000000000000007)<br>
-// CHECK: DW_AT_prototyped (0x00)<br>
<br>
// CHECK: DW_TAG_unspecified_parameters<br>
<br>
@@ -75,7 +72,6 @@ _x: .long 1<br>
// CHECK: DW_AT_decl_file ([[FILE]])<br>
// CHECK: DW_AT_decl_line (10)<br>
// CHECK: DW_AT_low_pc (0x0000000000000007)<br>
-// CHECK: DW_AT_prototyped (0x00)<br>
<br>
// CHECK: DW_TAG_unspecified_parameters<br>
<br>
<br>
<br>
<br>
_______________________________________________<br>
llvm-commits mailing list<br>
<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a><br>
<a href="https://urldefense.com/v3/__https:/lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits__;!!JmoZiZGBv3RvKRSx!oFY6rn6q7NLaL_YAxDThAs3yQWxPJ2yZAjofKkDP62ej1h-xh78EGsykA1dGGL2dAQ$" target="_blank">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</a><o:p></o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"MS Gothic"">宋方睿</span><o:p></o:p></p>
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