[llvm] r200422 - Turn on CU ranges if we've got multiple compile units in the same

[David Blaikie]

On Wed, Jan 29, 2014 at 2:26 PM, Eric Christopher <echristo at gmail.com>wrote:

> On Wed, Jan 29, 2014 at 2:23 PM, David Blaikie <dblaikie at gmail.com> wrote:
> >
> >
> >
> > On Wed, Jan 29, 2014 at 2:06 PM, Eric Christopher <echristo at gmail.com>
> > wrote:
> >>
> >> Author: echristo
> >> Date: Wed Jan 29 16:06:27 2014
> >> New Revision: 200422
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=200422&view=rev
> >> Log:
> >> Turn on CU ranges if we've got multiple compile units in the same
> >> module since there's no range guarantee that we could make given
> >> output order. This also fixes up the testcases that have multiple
> >> CUs to have the correct range offset.
> >
> >
> > What if LTO together a debug and non-debug module together? We'll still
> have
> > one CU, but we'll have functions that aren't in that CU - and incorrectly
> > describe that using an "all text" range?
> >
>
> ... Short of saying "always use DW_AT_ranges" I don't have a good
> solution for this. I'm somewhat down with that, but...
>

Perhaps you were addressing this with the "there's no range guarantee that
we could make given output order" (I'm not /quite/ sure how to parse that
sentence) - but I thought we'd settled on the idea that we could rely on
output order and just coalesce functions/ranges that came one after the
other. Or did you come up with some cases that breaks down for/that we care
about?

That way we'd still get high/low whenever it's contiguous, and otherwise
we'd use ranges.


>
> -eric
>
> >>
> >>
> >> Modified:
> >>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> >>     llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
> >>
> >> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=200422&r1=200421&r2=200422&view=diff
> >>
> >>
> ==============================================================================
> >> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> >> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Jan 29 16:06:27
> >> 2014
> >> @@ -1119,10 +1119,12 @@ void DwarfDebug::endSections() {
> >>    }
> >>
> >>    // For now only turn on CU ranges if we've explicitly asked for it,
> >> -  // we have -ffunction-sections enabled, or we've emitted a function
> >> -  // into a unique section. At this point all sections should be
> >> finalized
> >> -  // except for dwarf sections.
> >> -  HasCURanges = DwarfCURanges || UsedNonDefaultText ||
> >> +  // we have -ffunction-sections enabled, we've emitted a function
> >> +  // into a unique section, or we're using LTO. If we're using LTO then
> >> +  // we can't know that any particular function in the module is
> >> correlated
> >> +  // to a particular CU and so we need to be conservative. At this
> point
> >> all
> >> +  // sections should be finalized except for dwarf sections.
> >> +  HasCURanges = DwarfCURanges || UsedNonDefaultText || (CUMap.size() >
> 1)
> >> ||
> >>                  TargetMachine::getFunctionSections();
> >>  }
> >>
> >>
> >> Modified:
> >> llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll?rev=200422&r1=200421&r2=200422&view=diff
> >>
> >>
> ==============================================================================
> >> --- llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
> >> (original)
> >> +++ llvm/trunk/test/DebugInfo/X86/stmt-list-multiple-compile-units.ll
> Wed
> >> Jan 29 16:06:27 2014
> >> @@ -8,11 +8,11 @@
> >>  ; CHECK: .debug_info contents:
> >>  ; CHECK: DW_TAG_compile_unit
> >>  ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x00000000)
> >> -; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
> >> +; CHECK: DW_AT_ranges [DW_FORM_sec_offset]      (0x00000000)
> >>
> >>  ; CHECK: DW_TAG_compile_unit
> >>  ; CHECK: DW_AT_stmt_list [DW_FORM_sec_offset]   (0x0000003c)
> >> -; CHECK: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
> >> +; CHECK: DW_AT_ranges [DW_FORM_sec_offset]      (0x00000020)
> >>
> >>  ; CHECK: .debug_line contents:
> >>  ; CHECK-NEXT: Line table prologue:
> >> @@ -25,12 +25,12 @@
> >>
> >>  ; DWARF3: .debug_info contents:
> >>  ; DWARF3: DW_TAG_compile_unit
> >> -; DWARF3: DW_AT_stmt_list [DW_FORM_data4]   (0x00000000)
> >> -; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
> >> +; DWARF3: DW_AT_stmt_list [DW_FORM_data4]    (0x00000000)
> >> +; DWARF3: DW_AT_ranges [DW_FORM_data4]       (0x00000000)
> >>
> >>  ; DWARF3: DW_TAG_compile_unit
> >>  ; DWARF3: DW_AT_stmt_list [DW_FORM_data4]   (0x0000003c)
> >> -; DWARF3: DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
> >> +; DWARF3: DW_AT_ranges [DW_FORM_data4]      (0x00000020)
> >>
> >>  ; DWARF3: .debug_line contents:
> >>  ; DWARF3-NEXT: Line table prologue:
> >>
> >>
> >> _______________________________________________
> >> llvm-commits mailing list
> >> llvm-commits at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140129/5733c14a/attachment.html>