[llvm-dev] LLVMTargetMachine with optimization level passed from clang.

[Robinson, Paul via llvm-dev]

> -----Original Message-----
> From: mehdi.amini at apple.com [mailto:mehdi.amini at apple.com]
> Sent: Friday, January 06, 2017 12:49 PM
> To: Robinson, Paul
> Cc: Sumanth Gundapaneni; llvm-dev at lists.llvm.org
> Subject: Re: [llvm-dev] LLVMTargetMachine with optimization level passed
> from clang.
> 
> 
> > On Jan 6, 2017, at 12:41 PM, Robinson, Paul <paul.robinson at sony.com>
> wrote:
> >
> >
> >
> >> -----Original Message-----
> >> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
> Mehdi
> >> Amini via llvm-dev
> >> Sent: Friday, January 06, 2017 11:10 AM
> >> To: Sumanth Gundapaneni
> >> Cc: LLVM Developers
> >> Subject: Re: [llvm-dev] LLVMTargetMachine with optimization level
> passed
> >> from clang.
> >>
> >>
> >>> On Jan 6, 2017, at 10:56 AM, Sumanth Gundapaneni
> >> <sgundapa at codeaurora.org> wrote:
> >>>
> >>> Here is a problem scenario.
> >>>
> >>> I want to enable a backend pass at -O2 or above.
> >>> if (TM->getOptLevel() >= CodeGenOpt::Default)
> >>>   addPass(&xxxxx);
> >>>
> >>> This pass will be run at -O1 too since clang is creating the
> >> TargetMachine with CodeGenOpt::Default for -O1.
> >>
> >> Right, you can’t.
> >
> > Can somebody explain why it's not a bug that -O1 and -O2 are identical?
> 
> This is only a CodegenOpts, I don’t think it *has to* be a bug that this
> option is the same between O1 and O2. There are many other diff between
> O1/O2
> 
> However I clearly don’t like that `llc -O1` and `clang -O1` are not using
> the same settings here: https://reviews.llvm.org/D28409

Awesome, thanks!
--paulr

> 
> 
> 
> —
> Mehdi