Bad unwind info generated on macOS for methods with stackalloc

[MichalStrehovsky]

There are two buckets:

• linkerscript, file was built for unsupported file format
• could not create compact unwind for X: does not use RBP or RSP based frame

The linkerscript one should go away when we get rid of the linkerscript (see comment on #1417).

ld: warning: ignoring file /Users/jonathan/Downloads/corert-master/tests/../bin/Product/OSX.x64.Debug/packaging/publish1/sdk/linkerscript, file was built for unsupported file format ( 0x2F 0x2A 0x0A 0x4C 0x69 0x63 0x65 0x6E 0x73 0x65 0x64 0x20 0x74 0x6F 0x20 0x74 ) which is not the architecture being linked (x86_64): /Users/jonathan/Downloads/corert-master/tests/../bin/Product/OSX.x64.Debug/packaging/publish1/sdk/linkerscript
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Runtime_EH__UnhandledExceptionFailFastViaClasslib: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__Int64ToDecStr: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__Int32ToDecStr: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__UInt32ToDecStr: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__UInt64ToDecStr: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__FormatExponent: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__FormatFixed: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_Globalization_FormatProvider_Number__DoubleToNumber: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Console_Interop_Sys__StrError: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_System_String__IndexOfAny_1: does not use RBP or RSP based frame
ld: warning: could not create compact unwind for _System_Private_CoreLib_Internal_Runtime_Augments_RuntimeAugments__NewMultiDimArray: does not use RBP or RSP based frame
ld: warning: can't parse dwarf compilation unit info in /Users/jonathan/Downloads/corert-master/tests/src/Simple/Reflection/obj/Debug/dnxcore50/native/Reflection.obj

[jkotas]

This is a real problem that leaks to broken stacks under debugger. I have run into it while working on #2157.

Repro:

• int Main() { throw new Exception("My exception"); }
• Compile it and run it on Mac under lldb

Result: The stacktrace of the crash is incomplete because of it contains one of these methods with broken unwind info. Thus, you cannot actually see where the crash is coming from.

It seems to have something to do with stackalloc.

[sandreenko]

Can anybody compile next program on OSX:
internal class Program { static unsafe int Main() { int bufferSize = 10; char* tmpBuffer = stackalloc char[bufferSize]; return tmpBuffer[0]; } }
with --codegenopt NgenDump=Main and paste output here?