[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 echristo at gmail.com
Wed Mar 26 13:14:57 PDT 2014


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

>>
>> 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 "}
>> >
>> >
>> > _______________________________________________
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>> > llvm-commits at cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
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