[llvm] r204795 - Follow-up to r204790: don't try to emit line tables if there are no functions with DI in the TU

[Eric Christopher]

But how do you know where/etc they are?

-eric

On Wed, Mar 26, 2014 at 1:33 PM, Timur Iskhodzhanov <timurrrr at google.com> wrote:
> 1 file/line number entry for a single jmp instruction.
>
>
> 2014-03-27 0:22 GMT+04:00 Eric Christopher <echristo at gmail.com>:
>
>> On Wed, Mar 26, 2014 at 1:20 PM, Timur Iskhodzhanov <timurrrr at google.com>
>> wrote:
>> >
>> >
>> >
>> > 2014-03-27 0:14 GMT+04:00 Eric Christopher <echristo at gmail.com>:
>> >
>> >> On Wed, Mar 26, 2014 at 1:00 PM, Timur Iskhodzhanov
>> >> <timurrrr at google.com>
>> >> wrote:
>> >> >
>> >> >
>> >> >
>> >> > 2014-03-26 19:24 GMT+04:00 David Blaikie <dblaikie at gmail.com>:
>> >> >
>> >> >> On Wed, Mar 26, 2014 at 4:24 AM, Timur Iskhodzhanov
>> >> >> <timurrrr at google.com>
>> >> >> wrote:
>> >> >> > Author: timurrrr
>> >> >> > Date: Wed Mar 26 06:24:36 2014
>> >> >> > New Revision: 204795
>> >> >> >
>> >> >> > URL: http://llvm.org/viewvc/llvm-project?rev=204795&view=rev
>> >> >> > Log:
>> >> >> > Follow-up to r204790: don't try to emit line tables if there are
>> >> >> > no
>> >> >> > functions with DI in the TU
>> >> >>
>> >> >> Hmm - is there any better way to do this? Should we only be building
>> >> >> line tables for those functions with DI? Then we'd just emit line
>> >> >> tables if we have any (non-empty) line tables to emit, right?
>> >> >
>> >> >
>> >> > Is there a handy function available for that? :)
>> >> >
>> >>
>> >> From DwarfDebug::beginFunction:
>> >>
>> >>   // If there's no debug info for the function we're not going to do
>> >> anything.
>> >>   if (!MMI->hasDebugInfo())
>> >>     return;
>> >>
>> >>   // Grab the lexical scopes for the function, if we don't have any of
>> >> those
>> >>   // then we're not going to be able to do anything.
>> >>   LScopes.initialize(*MF);
>> >>   if (LScopes.empty())
>> >>     return;
>> >>
>> >> -eric
>> >
>> >
>> > This is almost exactly the beginning of
>> > WinCodeViewLineTables::beginFunction() as of yesterday :)
>> > So yes, I'm aware of this and I do/did use it.
>> >
>> > However, IIUC it turns out that "if we don't have any [lexical scopes]
>> > then
>> > we're not going to be able to do anything" we still can emit minimal DI
>> > for
>> > a function. [see r204790 + r204791]
>>
>> Without looking (my backlog is insane) what's the info you're emitting for
>> it?
>>
>> -eric
>>
>> >
>> >> >> I assume these COFF line tables don't actually get referenced from
>> >> >> any
>> >> >> other debug info (since the rest of our info is DWARF), but I've
>> >> >> been
>> >> >> thinking of cleaning up our other line table handling code a bit so
>> >> >> that it's a bit more structured - letting the line table object
>> >> >> itself
>> >> >> decide whether it should be emitted (by virtue of being non-empty)
>> >> >> and
>> >> >> then having line table clients (CUs in DwarfDebug - no analogy for
>> >> >> COFF which has no line table client) query the line table to see if
>> >> >> it'll be there and attach the DW_AT_stmt_list if there will be a
>> >> >> line
>> >> >> table.
>> >> >>
>> >> >> - David
>> >> >>
>> >> >> >
>> >> >> > Added:
>> >> >> >     llvm/trunk/test/DebugInfo/COFF/asan2.ll
>> >> >> > Modified:
>> >> >> >     llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
>> >> >> >
>> >> >> > Modified:
>> >> >> > llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
>> >> >> > URL:
>> >> >> >
>> >> >> >
>> >> >> > http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp?rev=204795&r1=204794&r2=204795&view=diff
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > ==============================================================================
>> >> >> > --- llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
>> >> >> > (original)
>> >> >> > +++ llvm/trunk/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
>> >> >> > Wed
>> >> >> > Mar
>> >> >> > 26 06:24:36 2014
>> >> >> > @@ -304,11 +304,18 @@ void WinCodeViewLineTables::beginFunctio
>> >> >> >    }
>> >> >> >  }
>> >> >> >
>> >> >> > -void WinCodeViewLineTables::endFunction(const MachineFunction *)
>> >> >> > {
>> >> >> > +void WinCodeViewLineTables::endFunction(const MachineFunction
>> >> >> > *MF) {
>> >> >> >    if (!Asm || !CurFn)  // We haven't created any debug info for
>> >> >> > this
>> >> >> > function.
>> >> >> >      return;
>> >> >> >
>> >> >> > -  if (!CurFn->Instrs.empty()) {
>> >> >> > +  const Function *GV = MF->getFunction();
>> >> >> > +  assert(FnDebugInfo.count(GV) == true);
>> >> >>
>> >> >> "count == true" seems a bit confusing for a few reasons. Should that
>> >> >> be either just "assert(x.count(y))" or "assert(x.count(y) != 0)" (or
>> >> >> greater than zero or 1 or whatever). "== true" always reads as
>> >> >> weird/redundant to me.
>> >> >>
>> >> >> > +  assert(CurFn == &FnDebugInfo[GV]);
>> >> >> > +
>> >> >> > +  if (CurFn->Instrs.empty()) {
>> >> >> > +    FnDebugInfo.erase(GV);
>> >> >> > +    VisitedFunctions.pop_back();
>> >> >> > +  } else {
>> >> >> >      // Define end label for subprogram.
>> >> >> >      MCSymbol *FunctionEndSym =
>> >> >> > Asm->OutStreamer.getContext().CreateTempSymbol();
>> >> >> >      Asm->OutStreamer.EmitLabel(FunctionEndSym);
>> >> >> >
>> >> >> > Added: llvm/trunk/test/DebugInfo/COFF/asan2.ll
>> >> >> > URL:
>> >> >> >
>> >> >> >
>> >> >> > http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/COFF/asan2.ll?rev=204795&view=auto
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > ==============================================================================
>> >> >> > --- llvm/trunk/test/DebugInfo/COFF/asan2.ll (added)
>> >> >> > +++ llvm/trunk/test/DebugInfo/COFF/asan2.ll Wed Mar 26 06:24:36
>> >> >> > 2014
>> >> >> > @@ -0,0 +1,52 @@
>> >> >> > +; RUN: llc -mcpu=core2 -mtriple=i686-pc-win32 -O0 < %s |
>> >> >> > FileCheck
>> >> >> > --check-prefix=X86 %s
>> >> >> > +
>> >> >> > +; This LL file was generated by running clang on the following
>> >> >> > code
>> >> >> > with
>> >> >> > +; -fsanitize=address
>> >> >> > +; D:\asan.c:
>> >> >> > +; 1 unsigned char c = 42;
>> >> >> > +
>> >> >> > +; Just make sure we don't try to emit the line table.
>> >> >> > +; X86-NOT: .section        .debug$S,"rn"
>> >> >> > +
>> >> >> > +; ModuleID = 'asan.c'
>> >> >> > +target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
>> >> >> > +target triple = "i686-pc-win32"
>> >> >> > +
>> >> >> > + at c = global { i8, [63 x i8] } { i8 42, [63 x i8] zeroinitializer
>> >> >> > },
>> >> >> > align 32
>> >> >> > + at llvm.global_ctors = appending global [1 x { i32, void ()* }] [{
>> >> >> > i32,
>> >> >> > void ()* } { i32 1, void ()* @asan.module_ctor }]
>> >> >> > + at __asan_gen_ = private constant [7 x i8] c"asan.c\00", align 1
>> >> >> > + at __asan_gen_1 = private unnamed_addr constant [2 x i8] c"c\00",
>> >> >> > align 1
>> >> >> > + at 0 = internal global [1 x { i32, i32, i32, i32, i32, i32 }] [{
>> >> >> > i32,
>> >> >> > i32, i32, i32, i32, i32 } { i32 ptrtoint ({ i8, [63 x i8] }* @c to
>> >> >> > i32), i32
>> >> >> > 1, i32 64, i32 ptrtoint ([2 x i8]* @__asan_gen_1 to i32), i32
>> >> >> > ptrtoint ([7 x
>> >> >> > i8]* @__asan_gen_ to i32), i32 0 }]
>> >> >> > + at llvm.global_dtors = appending global [1 x { i32, void ()* }] [{
>> >> >> > i32,
>> >> >> > void ()* } { i32 1, void ()* @asan.module_dtor }]
>> >> >> > +
>> >> >> > +define internal void @asan.module_ctor() {
>> >> >> > +  call void @__asan_init_v3()
>> >> >> > +  call void @__asan_register_globals(i32 ptrtoint ([1 x { i32,
>> >> >> > i32,
>> >> >> > i32, i32, i32, i32 }]* @0 to i32), i32 1)
>> >> >> > +  ret void
>> >> >> > +}
>> >> >> > +
>> >> >> > +declare void @__asan_init_v3()
>> >> >> > +
>> >> >> > +declare void @__asan_before_dynamic_init(i32)
>> >> >> > +
>> >> >> > +declare void @__asan_after_dynamic_init()
>> >> >> > +
>> >> >> > +declare void @__asan_register_globals(i32, i32)
>> >> >> > +
>> >> >> > +declare void @__asan_unregister_globals(i32, i32)
>> >> >> > +
>> >> >> > +define internal void @asan.module_dtor() {
>> >> >> > +  call void @__asan_unregister_globals(i32 ptrtoint ([1 x { i32,
>> >> >> > i32,
>> >> >> > i32, i32, i32, i32 }]* @0 to i32), i32 1)
>> >> >> > +  ret void
>> >> >> > +}
>> >> >> > +
>> >> >> > +!llvm.dbg.cu = !{!0}
>> >> >> > +!llvm.module.flags = !{!3, !4}
>> >> >> > +!llvm.ident = !{!5}
>> >> >> > +
>> >> >> > +!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"clang
>> >> >> > version 3.5.0 ", i1 false, metadata !"", i32 0, metadata !2,
>> >> >> > metadata
>> >> >> > !2,
>> >> >> > metadata !2, metadata !2, metadata !2, metadata !"", i32 2} ; [
>> >> >> > DW_TAG_compile_unit ] [D:\/asan.c] [DW_LANG_C99]
>> >> >> > +!1 = metadata !{metadata !"asan.c", metadata !"D:\5C"}
>> >> >> > +!2 = metadata !{}
>> >> >> > +!3 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
>> >> >> > +!4 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
>> >> >> > +!5 = metadata !{metadata !"clang version 3.5.0 "}
>> >> >> >
>> >> >> >
>> >> >> > _______________________________________________
>> >> >> > llvm-commits mailing list
>> >> >> > llvm-commits at cs.uiuc.edu
>> >> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> >> >
>> >> >
>> >> >
>> >> > _______________________________________________
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>> >> > llvm-commits at cs.uiuc.edu
>> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> >> >
>> >
>> >
>
>