[PATCH] D31905: Exit early from start line search for FunctionNameKind::None

[Brian Cain via llvm-commits]

The resulting breakage is only to the feature that’s new as of r294231, or does it impact more than that?  

 

Could we do this partial revert first and then in a subsequent commit add the code to support both use cases?

 

-Brian

 

From: David Blaikie [mailto:dblaikie at gmail.com] 
Sent: Monday, April 10, 2017 3:53 PM
To: reviews+D31905+public+410e06a7b468ba68 at reviews.llvm.org; bcain at codeaurora.org; sque at google.com; echristo at gmail.com
Cc: llvm-commits at lists.llvm.org
Subject: Re: [PATCH] D31905: Exit early from start line search for FunctionNameKind::None

 

I would guess this would then cause the line to not be retrieved when it might be desired? But I haven't thought about it too hard (hopefully Simon can chime in).

If that's the case & the existing functionality needs to be preserved, then maybe two functions will be needed or some other way to communicate "actually I don't need the line" (pass it by pointer instead of reference - null pointer indicates "not needed")

 

On Mon, Apr 10, 2017 at 1:46 PM Brian Cain via Phabricator <reviews at reviews.llvm.org <mailto:reviews at reviews.llvm.org> > wrote:

bcain created this revision.

https://reviews.llvm.org/rL294231 introduced a regression -- memory consumption for llvm-objdump during disassembly of ~500MB hexagon elf file was ~1.5GiB higher after that commit.

This change restores the previous behavior -- exit the search early for FunctionNameKind::None, saving some memory allocation.


Repository:
  rL LLVM

https://reviews.llvm.org/D31905

Files:
  lib/DebugInfo/DWARF/DWARFContext.cpp


Index: lib/DebugInfo/DWARF/DWARFContext.cpp
===================================================================
--- lib/DebugInfo/DWARF/DWARFContext.cpp
+++ lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -466,6 +466,9 @@
                                                   FunctionNameKind Kind,
                                                   std::string &FunctionName,
                                                   uint32_t &StartLine) {
+  if (Kind == FunctionNameKind::None)
+    return false;
+
   // The address may correspond to instruction in some inlined function,
   // so we have to build the chain of inlined functions and take the
   // name of the topmost function in it.
@@ -477,7 +480,7 @@
   const DWARFDie &DIE = InlinedChain[0];
   bool FoundResult = false;
   const char *Name = nullptr;
-  if (Kind != FunctionNameKind::None && (Name = DIE.getSubroutineName(Kind))) {
+  if ((Name = DIE.getSubroutineName(Kind))) {
     FunctionName = Name;
     FoundResult = true;
   }



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