[Mono] Fix Mono Windows x86 build and runtime crash. #74639
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Tagging subscribers to this area: @dotnet/area-system-runtime-intrinsics Issue DetailsWhen trying to validate a fix on Mono Windows x86, runtime crashed with stack overflow. After some investigation it turns out that Mono Windows x86 have SIMD disabled, but S.P.C was still build with causing a stack overflow when called at runtime. There was already a fallback implemented in Mono to handle case where runtime is build without SIMD support but code calls There was also a warning in NOTE, Mono Windows x86 is not an official supported configuration, but can still be used for testing and validation of x86 codegen and runtime behaviors (Mono x86 is still supported on other platforms), so there is still a value fixing it when needed.
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Trying to validate a fix on x86 Windows Mono crashed runtime with
stack overflow. After some investigation it turns out that Mono
Windows x86 have SIMD disabled, but S.P.C was still build with
System.Runtime.Intrinsics support and implementation of methods
like get_IsSupported is implemented as follow:
.method public hidebysig specialname static
bool get_IsSupported() cil managed
{
// Code size 6 (0x6)
.maxstack 8
IL_0000: call bool System.Runtime.Intrinsics.X86.Popcnt::get_IsSupported()
IL_0005: ret
} // end of method Popcnt::get_IsSupported
causing a stack overflow when called at runtime.
There was already a fallback implemented in Mono runtime to handle
case where runtime is build without SIMD support but code calls
get_IsHardwareAccelerated, fix extends that check to include
get_IsSuppored as well. Fix also make sure we won't add support for
System.Runtime.Intrinsics in S.P.C for Mono Windows x86 builds.
There was also a warning in debugger-agent.c when building debug
that caused build to fail, including fix for that as well.
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Looks like we have configurations that assumes fallback through runtime code, so can't add get_IsSupported check in this PR, so PR will only make sure Mono Windows x86 build includes the not supported source files into its build of affected System.Numerics classes. |
Several CI landes like llvmfullaot Linux x64 depends on fallback.
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Failure in Mono Linux argm64 Debug lane appears on other PR's and not related to changes done in this PR. |
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When trying to validate a fix on Mono Windows x86, runtime crashed with stack overflow. After some investigation it turns out that Mono Windows x86 have SIMD disabled, but S.P.C was still build with
System.Runtime.Intrinsicssupport and implementation of methods likeget_IsSupportedis implemented as follow:causing a stack overflow when called at runtime.
Fix make sure we won't add support for
System.Runtime.Intrinsicsin S.P.C for Mono Windows x86 builds.There was also a warning in
debugger-agent.cwhen building debug that caused build to fail, including fix for that as well.NOTE, Mono Windows x86 is not an official supported configuration, but can still be used for testing and validation of x86 codegen and runtime behaviors (Mono x86 is still supported on other platforms), so there is still a value fixing it when needed.