[llvm] r204795 - Follow-up to r204790: don't try to emit line tables if there are no functions with DI in the TU
Timur Iskhodzhanov
timurrrr at google.com
Wed Mar 26 13:20:43 PDT 2014
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]
>> 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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