<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Apr 5, 2017, at 3:13 PM, Felipe Cypriano via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
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<div class=""><div style="font-family:Arial;" class="">Hello,<br class=""></div>
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<div style="font-family:Arial;" class="">We have updated our codebase to Xcode 8.3 and to my knowledge that means we are now using Swift 3.1 compiler. Our first release using it - almost no change to code since we release very often - had a huge increase in crashes related to memory all over the codebase. The solution was to turn off all Swift optimizations. This forum thread is related to the problem: <a href="https://forums.developer.apple.com/message/219236#219236" class="">https://forums.developer.apple.com/message/219236#219236</a><br class=""></div>
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<div style="font-family:Arial;" class="">I have never debugged an compiler related problem so I'm looking into advice on how to pin point what the problem really is. Why our code works with -Onone but crashes with both -O and -Owholemodule? Any tips would be appreciated.<br class=""></div></div></div></blockquote><div><br class=""></div><div>So this is happening with just -O (i.e. no whole module). In that case I would do this. Take the main command line that you are passing to swiftc and add the option -###. This causes the driver to dump the subcommands that it is going to run. So for instance if I have the following command line:</div><div><br class=""></div><div> xcrun swiftc test.swift test2.swift main.swift -module-name Test -O -###</div><div><br class=""></div><div>I get the following output:</div><div><br class=""></div><div><div><div>/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c -primary-file test.swift test2.swift main.swift -target x86_64-apple-macosx10.9 -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -color-diagnostics -O -module-name Test -o /var/folders/z0/zl5mqfcj25db895ldcgpzdxm0000gn/T/test-00eef5.o</div><div>/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c test.swift -primary-file test2.swift main.swift -target x86_64-apple-macosx10.9 -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -color-diagnostics -O -module-name Test -o /var/folders/z0/zl5mqfcj25db895ldcgpzdxm0000gn/T/test2-a29a57.o</div><div>/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c test.swift test2.swift -primary-file main.swift -target x86_64-apple-macosx10.9 -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -color-diagnostics -O -module-name Test -o /var/folders/z0/zl5mqfcj25db895ldcgpzdxm0000gn/T/main-bfcad6.o</div><div>/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld /var/folders/z0/zl5mqfcj25db895ldcgpzdxm0000gn/T/test-00eef5.o /var/folders/z0/zl5mqfcj25db895ldcgpzdxm0000gn/T/test2-a29a57.o /var/folders/z0/zl5mqfcj25db895ldcgpzdxm0000gn/T/main-bfcad6.o -force_load /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/arc/libarclite_macosx.a -framework CoreFoundation -syslibroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -lobjc -lSystem -arch x86_64 -L /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/macosx -rpath /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/macosx -macosx_version_min 10.9.0 -no_objc_category_merging -o Test</div><div class=""><br class=""></div></div><div class="">Notice how the -O is on each line. This is the flag that ensures that optimizations are being run. To disable optimizations on a specific swift file, you can add to the -c line the flag:</div><div class=""><br class=""></div><div class=""> -disable-sil-perf-optzns</div><div class=""><br class=""></div><div class="">This will disable sil performance optimizations while ensuring that everything else is exactly as if one is running with optimizations enabled.</div><div class=""><br class=""></div><div class="">Then I would create a little script that takes in these command lines and puts -disable-sil-perf-optzns on all such .o command lines except for 1. This will then allow you to figure out which specific compilation invocation is causing the miscompile.</div><div class=""><br class=""></div></div><div>Why don't you try that and respond back if it works for you?</div><div><br class=""></div><div>Michael</div><br class=""><blockquote type="cite" class=""><div class=""><div class="">
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<div style="font-family:Arial;" class="">Thanks,<br class=""></div>
<div style="font-family:Arial;" class="">Felipe Cypriano</div>
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