[llvm-dev] RFC: Cleaning up the Itanium demangler

[Joerg Sonnenberger via llvm-dev]

On Thu, Jun 22, 2017 at 08:34:02AM -0700, Erik Pilkington wrote:
> 
> 
> On 6/22/17 7:50 AM, Joerg Sonnenberger via llvm-dev wrote:
> > On Wed, Jun 21, 2017 at 04:42:40PM -0700, Erik Pilkington via llvm-dev wrote:
> > > I've been working on fixing this by parsing first into an AST structure, and
> > > then traversing that AST to produce a demangled string. This provides a
> > > significant performance improvement and also make the demangler somewhat
> > > more clean.
> > How does it far in terms of code size? One of the big problems with the
> > libcxxabi demangler is its size. It's at least twice as large as the one
> > in elftoolchain, even ignoring some possible feature differences.
> Looks pretty good, I'm guessing this is because all the string operations
> aren't getting inlined into the parser anymore.
> Before this patch:
> __TEXT    __DATA  __OBJC    others  dec       hex
> 247293    0       0         1248    248541    3cadd
> libc++abi.a(cxa_demangle.cpp.o)
> 
> After this patch:
> __TEXT    __DATA  __OBJC    others  dec       hex
> 137723    4216    0         6016    147955    241f3
> libc++abi.a(cxa_demangle.cpp.o)

Better, but still huge compared to:

   text    data     bss     dec     hex filename
  44560       0       0   44560    ae10 rt_libelftc_dem_gnu3.pico

Joerg