[PATCH] D95518: [Debug-Info][XCOFF] support dwarf for XCOFF for assembly output

[Jason Liu via Phabricator via llvm-commits]

jasonliu added inline comments.


================
Comment at: llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp:1804-1807
+  // When -function-sections is enabled, generating function section end symbol
+  // to tell debug line section where is the end of current function section.
+  if (TM.getFunctionSections() && !MAI->usesDwarfFileAndLocDirectives() &&
+      MMI->hasDebugInfo())
----------------
shchenz wrote:
> hubert.reinterpretcast wrote:
> > @jasonliu, I'd like your analysis of how this interacts with explicit sections.
> `explicit sections` are generated when `-fdata-sections` is enabled? If so, I think debugging functionality should not be impacted. We only need to worry about the "text" section for debug line. For `explicit sections` functionality, I guess it should not be impacted too as we only add new labels, not data, like `vbyte`, `byte`
> 
> Anyway, your input is appreciated @jasonliu 
It seems that we want to generate a section end label on every text csect here.
If that's the case, then it doesn't seem like we are generating them correctly when explicit section for text section is enabled. An example would be:
```
int bar() {return 1;}
int __attribute__((section ("explicit_main_sec"))) main() {
  return bar();
}
```
I don't see a `L..sec_end` for `.text[PR]`.

A side note when I was trying things: it seems we have a subtle bug when we enables -function-sections and specify an explicit section for a function. We don't generate a label for the function entry point in this case, and we don't have the correct function entry point stored in the function descriptor section. 
The bug is not related to this patch, and we need to fix it in another patch. But it affects how we want to construct a test case in this patch.


================
Comment at: llvm/test/DebugInfo/XCOFF/empty.ll:2
+
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff < %s | \
+; RUN:   FileCheck %s --check-prefix=ASM32
----------------
We should add test for -ffunction-sections, and possible explicit sections as well.


================
Comment at: llvm/test/DebugInfo/XCOFF/empty.ll:51
+; ASM32-NEXT:   li 4, 0
+; ASM32-NEXT:  L..tmp1:
+; ASM32-NEXT:  L..tmp2:
----------------
It might not be big deal, but it seems we are generating an extra label for no reason?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95518/new/

https://reviews.llvm.org/D95518