`build_detect_platform` seems to detect incorrect features for iOS

rajivshah3 commented 2 years ago

I'm having trouble building for iOS. I think I was able to get one of the recent 6.x releases to build a while ago, but it seems like something may have changed in 7.x that's causing problems for iOS.

Following the instructions in INSTALL.md, I first run TARGET_OS=IOS make static_lib -j8: https://github.com/facebook/rocksdb/blob/9454e744ed0ca4bb27ebcd8d4f79c59ef723adcf/INSTALL.md?plain=1#L180-L181

I get two groups of errors:

./util/fastrange.h:62:5: error: unknown type name '__uint128_t'
    __uint128_t wide = __uint128_t{range} * hash;
    ^
./util/fastrange.h:62:24: error: use of undeclared identifier '__uint128_t'
    __uint128_t wide = __uint128_t{range} * hash;
                       ^
./util/fastrange.h:62:35: error: expected ';' at end of declaration
    __uint128_t wide = __uint128_t{range} * hash;
                                  ^
                                  ;
./util/fastrange.h:55:35: error: unused parameter 'hash' [-Werror,-Wunused-parameter]
  static inline Range Fn(uint64_t hash, Range range) {
                                  ^
./util/fastrange.h:55:47: error: unused parameter 'range' [-Werror,-Wunused-parameter]
  static inline Range Fn(uint64_t hash, Range range) {
                                              ^

In file included from cache/lru_cache.cc:10:
./cache/lru_cache.h:290:11: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
  virtual ~LRUCacheShard() override = default;
          ^
cache/lru_cache.cc:673:18: note: in defaulted destructor for 'rocksdb::LRUCacheShard' first required here
      shards_[i].~LRUCacheShard();
                 ^
./cache/lru_cache.h:290:11: note: if you supply your own aligned allocation functions, use -faligned-allocation to silence this diagnostic
  virtual ~LRUCacheShard() override = default;
          ^

(the second one looks similar to #4064)

I noticed that in the generated make_config.mk, -DHAVE_UINT128_EXTENSION is in PLATFORM_CCFLAGS and PLATFORM_CXXFLAGS:

PLATFORM_CCFLAGS= -DROCKSDB_PLATFORM_POSIX -DROCKSDB_LIB_IO_POSIX  -DOS_MACOSX -DIOS_CROSS_COMPILE -DROCKSDB_LITE -Wshorten-64-to-32  -DHAVE_BMI -DHAVE_UINT128_EXTENSION -DROCKSDB_SUPPORT_THREAD_LOCAL -DHAVE_FULLFSYNC
PLATFORM_CXXFLAGS=-std=c++17  -DROCKSDB_PLATFORM_POSIX -DROCKSDB_LIB_IO_POSIX  -DOS_MACOSX -DIOS_CROSS_COMPILE -DROCKSDB_LITE -Wshorten-64-to-32  -DHAVE_BMI -DHAVE_UINT128_EXTENSION -DROCKSDB_SUPPORT_THREAD_LOCAL -DHAVE_FULLFSYNC

Confused as to why I got the error when it seems like the __uint128 test in build_tools/build_detect_platform must have passed, I tried compiling that test by itself in a separate file:

The following command works:

g++ test.cc -o test.o

But I noticed that the Makefile will run this when targeting iOS: https://github.com/facebook/rocksdb/blob/4f9c0fd083d00bacd86b723f7789658ccfd3f108/Makefile#L2423 So I tried something similar:

xcrun -sdk iphonesimulator g++ -isysroot $(xcrun --sdk iphonesimulator --show-sdk-path) -arch i686 -arch x86_64 test.cc -o test.o

It seems like targeting i686 causes this to fail, because it succeeds if I only pass -arch x86_64:

$ xcrun -sdk iphonesimulator g++ -isysroot $(xcrun --sdk iphonesimulator --show-sdk-path) -arch i686 test.cc -o test.o 
test.cc:4:5: error: unknown type name '__uint128_t'
    __uint128_t b = __uint128_t(a) * a;
    ^
test.cc:4:21: error: use of undeclared identifier '__uint128_t'
    __uint128_t b = __uint128_t(a) * a;
                    ^
2 errors generated.

The same error is shown when targeting armv7 for iOS (xcrun -sdk iphoneos g++ -isysroot $(xcrun --sdk iphoneos --show-sdk-path) -arch armv7 test.cc -o test.o), but targeting arm64 alone succeeds.

I don't personally don't need support for any of the 32-bit architectures, but it seems like the Makefile tries to target them: https://github.com/facebook/rocksdb/blob/4f9c0fd083d00bacd86b723f7789658ccfd3f108/Makefile#L2421-L2433

Expected behavior

RocksDB compiles successfully for iOS

Actual behavior

Errors are shown

Steps to reproduce the behavior

TARGET_IOS make static_lib -j8

Here's my output of clang -v (I have Xcode 13.4 installed) :

Apple clang version 13.1.6 (clang-1316.0.21.2.5)
Target: x86_64-apple-darwin21.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

I'm on macOS Monterey 12.4 with an Intel-based Mac, using the macOS 12.3 SDK and iOS 15.5 SDK

rajivshah3 commented 2 years ago

It seems like it compiles successfully if I remove -arch i686 and -arch armv6 -arch armv7 -arch armv7s from the Makefile

siying commented 2 years ago

CC several people who has contributed to PRs related to building on ARM: @siddontang @etherond @adamretter

adamretter commented 2 years ago

@siying I'm afraid I don't have any knowledge of IOS or the equipment to test for it. Regards the comment about 32 bit support, if I recall we support Linux on Intel and ARM currently for this

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