OSR method may require kept-alive this in cases where base method didn't

A couple examples in the OSR stress weekend experimental runs.

Because of inlining the reporting of this for generic contexts is needed in an OSR method, but not in the base method. This violates an assumption that both methods would agree on this aspect.

runtime/src/coreclr/jit/lclvars.cpp

Lines 6193 to 6204 in ca7f199

    
           // OSR methods use the original method slot for the cached kept alive this, 
        
           // so don't need to allocate  a slot on the new frame. 
        
           if (opts.IsOSR()) 
        
           { 
        
               if (lvaKeepAliveAndReportThis()) 
        
               { 
        
                   PatchpointInfo* ppInfo = info.compPatchpointInfo; 
        
                   assert(ppInfo->HasKeptAliveThis()); 
        
                   int originalOffset             = ppInfo->KeptAliveThisOffset(); 
        
                   lvaCachedGenericContextArgOffs = originalFrameStkOffs + originalOffset; 
        
               } 
        
           }

Should not be too hard to report the kept-alive this in the OSR method on it's part of the frame. Looks like CodeGen::genReportGenericContextArg might just work for OSR frames, though that needs to be verified.

category:correctness
theme:osr
skill-level:intermediate
cost:small
impact:small

Fixed by #51057.

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OSR method may require kept-alive this in cases where base method didn't #47532

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	// OSR methods use the original method slot for the cached kept alive this,
	// so don't need to allocate a slot on the new frame.
	if (opts.IsOSR())
	{
	if (lvaKeepAliveAndReportThis())
	{
	PatchpointInfo* ppInfo = info.compPatchpointInfo;
	assert(ppInfo->HasKeptAliveThis());
	int originalOffset = ppInfo->KeptAliveThisOffset();
	lvaCachedGenericContextArgOffs = originalFrameStkOffs + originalOffset;
	}
	}

OSR method may require kept-alive this in cases where base method didn't #47532

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AndyAyersMS commented on Apr 27, 2021

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