Inefficient codegen with struct consisting of 2 SIMD vectors. #83749

Activity

1. MichalPetryka

   added

   tenet-performancePerformance related issuePerformance related issue

   on Mar 21, 2023
2. ghost added

   area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMICLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI

   on Mar 21, 2023
3. ghost added

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Mar 21, 2023
5. JulieLeeMSFT

   assigned

   jakobbotsch

   on Mar 27, 2023
6. jakobbotsch commented on Mar 30, 2023

   

   jakobbotsch

   on Mar 30, 2023

   Member

   More actions

   The problem is here:
   

   runtime/src/coreclr/jit/lclvars.cpp

   Lines 2252 to 2270 in e43ddbf

   	#ifdef FEATURE_SIMD
   	// Check to see if this is a SIMD type.
   	// We will only check this if we have already found a SIMD type, which will be true if
   	// we have encountered any SIMD intrinsics.
   	if (compiler->usesSIMDTypes() && (fieldInfo.fldSize == 0) && compiler->isSIMDorHWSIMDClass(fieldInfo.fldTypeHnd))
   	{
   	unsigned simdSize;
   	CorInfoType simdBaseJitType = compiler->getBaseJitTypeAndSizeOfSIMDType(fieldInfo.fldTypeHnd, &simdSize);
   	// We will only promote fields of SIMD types that fit into a SIMD register.
   	if (simdBaseJitType != CORINFO_TYPE_UNDEF)
   	{
   	if ((simdSize >= compiler->minSIMDStructBytes()) && (simdSize <= compiler->maxSIMDStructBytes()))
   	{
   	fieldInfo.fldType = compiler->getSIMDTypeForSize(simdSize);
   	fieldInfo.fldSize = simdSize;
   	}
   	}
   	}
   	#endif // FEATURE_SIMD

   Since B uses no SIMD intrinsics the JIT assumes the fields of Vector2x128 are not SIMD types and we end up skipping promotion due to that.
7. ghost added

   in-prThere is an active PR which will close this issue when it is mergedThere is an active PR which will close this issue when it is merged

   on Mar 30, 2023
8. JulieLeeMSFT

   removed

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Apr 4, 2023
9. JulieLeeMSFT

   added this to the 8.0.0 milestone on Apr 4, 2023
10. ghost removed

    in-prThere is an active PR which will close this issue when it is mergedThere is an active PR which will close this issue when it is merged

    on Jun 1, 2023
11. ghost added

    in-prThere is an active PR which will close this issue when it is mergedThere is an active PR which will close this issue when it is merged

    on Jun 6, 2023
12. jakobbotsch

    added

    Priority:2Work that is important, but not critical for the releaseWork that is important, but not critical for the release

    on Jun 20, 2023
13. jakobbotsch

    closed this as completedin #84122on Jul 5, 2023
14. ghost removed

    in-prThere is an active PR which will close this issue when it is mergedThere is an active PR which will close this issue when it is merged

    on Jul 5, 2023
15. ghost locked as resolved and limited conversation to collaborators on Aug 5, 2023