> On Aug 6, 2017, at 16:16, Michael Gottesman <mgottes...@apple.com> wrote:
>> On Aug 6, 2017, at 11:11 AM, David Zarzycki via swift-dev
>> <email@example.com> wrote:
>> Unless I’m missing a build-script flag, it seems to me that compiling the
>> Swift stdlib with the unoptimized debug swift compiler takes about 15
>> minutes on a fast machine.
> I am assuming that you mean a debug swift compiler building an optimized
I’m building the debug swift compiler via ./utils/build-script -r —debug-swift.
I assume, perhaps wrongly, that implies a debug stdlib.
>> Other than forcing the type checker to be optimized, what if any tricks can
>> I use to building the stdlib faster with the debug compiler? Is there a way
>> to tell Clang to enable the inliner and only the inliner during -O0 builds?
>> I have an anecdotal experiment that suggests that this would yield
>> appreciably faster Swift stdlib builds with the debug compiler (and
>> selfishly speaking, I can tolerate the minor impact on debugging that
>> inlining does to otherwise unoptimized code).
> Are building LLVM in release + Swift in debug? I.e.:
> —release-debuginfo --debug-swift --force-optimized-typechecker
Yes, with the exception that I cannot use —force-optimized-typechecker because
I’m hacking on the type checker. Otherwise, this is what I’m doing to make
debug builds go as fast as possible:
--llvm-targets-to-build X86 \
--skip-ios --skip-tvos --skip-watchos \
--skip-build-benchmarks true \
--build-swift-static-stdlib false \
--build-swift-static-sdk-overlay false \
--build-swift-dynamic-sdk-overlay false \
--build-swift-stdlib-unittest-extra false \
--extra-cmake-options \\-DCMAKE_CXX_FLAGS=-Werror=switch \
>>  – If one force inlines LLVM’s casting logic and associated callbacks
>> (like classof() and getKind()), then the Swift stdlib builds 18% faster on
>> my machine with the debug Swift compiler. One can imagine how much faster
>> the whole stdlib would compile if all trivial functions were inlined
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