lebedev.ri added inline comments.
================
Comment at: cfe/trunk/lib/CodeGen/BackendUtil.cpp:1426-1431
EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
if (CGOpts.ExperimentalNewPassManager)
AsmHelper.EmitAssemblyWithNewPassManager(Action, std::move(OS));
else
AsmHelper.EmitAssembly(Action, std::move(OS));
----------------
anton-afanasyev wrote:
> lebedev.ri wrote:
> > anton-afanasyev wrote:
> > > anton-afanasyev wrote:
> > > > lebedev.ri wrote:
> > > > > This isn't covered by any timer; if you look in `BackendUtil.cpp`,
> > > > > `EmitAssemblyHelper` actually has `CodeGenerationTime("codegen",
> > > > > "Code Generation Time")` timer.
> > > > Thanks, I'm to add it.
> > > Hmm, I've figured out this isn't needed: such new timer mostly coincides
> > > with "Backend" timer (above). Legacy `Timer CodeGenerationTime(...)` is
> > > bad example of doing right timing.
> > "Mostly coincides" may not be the best way to approach fine-grained
> > timings, i think? :)
> >
> > I have noticed this because when i looked at the produced time flame graph,
> > there's large section in the end that is covered only by `"Backend"` timer,
> > but nothing else. Now, i'm not going to say whether or not that extra
> > section
> > should or should not be within `"Backend"` timer, but it certainly should
> > *also*
> > be within `"codegen"` timer. Or is there no codegen time spent there?
> > {F10062322}
> > {F10062316}
> "Mostly coincides" here means "identical" I believe, the difference is
> auxiliary stuff.
> Please look at `clang::EmitBackendOutput()`, `"Backend"` timer is outer for
> `"codegen"` one.
Then we are talking about different things using the same name.
There are two distinct codegen steps:
1. clang AST -> LLVM IR codegen
(after that, all the opt passes run)
2. LLVM IR -> final assembly. This happens after all the opt middle-end passes.
Those are *different* codegen's.
Repository:
rL LLVM
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D58675/new/
https://reviews.llvm.org/D58675
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