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

Tue Apr 1 10:02:59 PDT 2014

Sounds good.

On Tue, Apr 1, 2014 at 3:08 AM, Timur Iskhodzhanov <timurrrr at google.com> wrote:
> Let's continue the discussion on the r204790 commit thread.
>
> 2014-04-01 13:55 GMT+04:00 Timur Iskhodzhanov <timurrrr at google.com>:
>> 2014-04-01 4:07 GMT+04:00 Eric Christopher <echristo at gmail.com>:
>>> The MI has a DebugLoc and none of the IR do?
>>
>> Frankly, I'm confused by all this stuff myself :)
>>
>> Looking at
>>   test/DebugInfo/COFF/tail-call-without-lexical-scopes.ll
>> I think the case is that IR *has* !dbg tags, yet
>> LexicalScopes::empty() actually returned "true" for this MF.
>>
>>> Otherwise a function is considered a lexical scope for purposes of the
>>> other check.
>>>
>>> -eric
>>>
>>> On Wed, Mar 26, 2014 at 1:47 PM, Timur Iskhodzhanov <timurrrr at google.com> wrote:
>>>> the WinCodeViewLineTables::beginInstruction is called and the MI happens to
>>>> have a DebugLoc.
>>>>
>>>> That's in fact exactly the scenario r204790 has fixed - processing of a
>>>> function without a lexical scope but with at least one MI having DL.
>>>>
>>>> 2014-03-27 0:36 GMT+04:00 Eric Christopher <echristo at gmail.com>:
>>>>
>>>>> 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
>>>>> >> >> >
>>>>> >> >> >
>>>>> >> >> >
>>>>> >> >> > _______________________________________________
>>>>> >> >> > llvm-commits mailing list
>>>>> >> >> > llvm-commits at cs.uiuc.edu
>>>>> >> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>>>> >> >> >
>>>>> >> >
>>>>> >> >
>>>>> >
>>>>> >
>>>>
>>>>