Treat TZCNT/POPCNT/LZCNT as never negative

[trympet]

Check for population count, trailing zero count, and leading zero count intrinsics when determining integral rage.

This change makes most of these casts redundant:

Closes #64909

[ghost]

Tagging subscribers to this area: @JulieLeeMSFT
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Check for population count, trailing zero count, and leading zero count intrinsics when determining integral rage.

Closes #64909

Author:	trympet
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[dnfadmin]

All CLA requirements met.

[EgorBo]

Looks like this PR found a couple of improvements 👍

Top method improvements (bytes):
          -3 (-0.11 % of base) : 18228.dasm - HttpParser`1:ParseHeaders(Http1ParsingHandler,byref):bool:this
          -3 (-0.11 % of base) : 19599.dasm - HttpParser`1:ParseHeaders(Http1ParsingHandler,byref):bool:this
          -3 (-0.11 % of base) : 46626.dasm - HttpParser`1:ParseHeaders(Http1ParsingHandler,byref):bool:this
          -3 (-0.12 % of base) : 49052.dasm - HttpParser`1:ParseHeaders(Http1ParsingHandler,byref):bool:this
          -3 (-0.12 % of base) : 52210.dasm - HttpParser`1:ParseHeaders(Http1ParsingHandler,byref):bool:this
          -3 (-0.11 % of base) : 55814.dasm - HttpParser`1:ParseHeaders(Http1ParsingHandler,byref):bool:this
          -3 (-0.14 % of base) : 10768.dasm - HttpParser`1:ParseHeaders(ParsingAdapter,byref):bool:this
          -3 (-0.14 % of base) : 11823.dasm - HttpParser`1:ParseHeaders(ParsingAdapter,byref):bool:this
          -3 (-0.14 % of base) : 12311.dasm - HttpParser`1:ParseHeaders(ParsingAdapter,byref):bool:this
          -3 (-0.08 % of base) : 49311.dasm - HttpParser`1:ParseMultiSpanHeader(Http1ParsingHandler,byref):int:this
          -3 (-0.08 % of base) : 52524.dasm - HttpParser`1:ParseMultiSpanHeader(Http1ParsingHandler,byref):int:this
          -3 (-0.27 % of base) : 39745.dasm - Utf8Utility:GetPointerToFirstInvalidByte(long,int,byref,byref):long
          -3 (-0.19 % of base) : 44609.dasm - Utf8Utility:GetPointerToFirstInvalidByte(long,int,byref,byref):long
          -3 (-0.20 % of base) : 50722.dasm - Utf8Utility:GetPointerToFirstInvalidByte(long,int,byref,byref):long
          -3 (-0.19 % of base) : 63703.dasm - Utf8Utility:GetPointerToFirstInvalidByte(long,int,byref,byref):long
          -2 (-0.15 % of base) : 49316.dasm - BufferExtensions:PositionOfAny(byref,ubyte,ubyte):Nullable`1
          -2 (-0.15 % of base) : 52527.dasm - BufferExtensions:PositionOfAny(byref,ubyte,ubyte):Nullable`1
          -2 (-0.29 % of base) : 10762.dasm - MemoryExtensions:IndexOfAny(ReadOnlySpan`1,ubyte,ubyte):int
          -2 (-0.29 % of base) : 11809.dasm - MemoryExtensions:IndexOfAny(ReadOnlySpan`1,ubyte,ubyte):int
          -2 (-0.29 % of base) : 18229.dasm - MemoryExtensions:IndexOfAny(ReadOnlySpan`1,ubyte,ubyte):int

these functionf are pretty perf sensitive + we won't have to uglify code with uint casts, you can probably even remove some existing uint casts (e.g. I put it in IndexOf) if you want 🙂

[trympet]

these functionf are pretty perf sensitive + we won't have to uglify code with uint casts, you can probably even remove some existing uint casts (e.g. I put it in IndexOf) if you want 🙂

@EgorBo, Are you referring to this, for instance?

runtime/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Byte.cs

Lines 529 to 530 in 3fc8b09

	// Find bitflag offset of first match and add to current offset
	return (int)(offset + (uint)BitOperations.TrailingZeroCount(matches));

[EgorBo]

these functionf are pretty perf sensitive + we won't have to uglify code with uint casts, you can probably even remove some existing uint casts (e.g. I put it in IndexOf) if you want 🙂

@EgorBo, Are you referring to this, for instance?

runtime/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Byte.cs

Lines 529 to 530 in 3fc8b09

	// Find bitflag offset of first match and add to current offset
	return (int)(offset + (uint)BitOperations.TrailingZeroCount(matches));

no, I meant this: https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Char.cs#L612

[trympet]

these functionf are pretty perf sensitive + we won't have to uglify code with uint casts, you can probably even remove some existing uint casts (e.g. I put it in IndexOf) if you want 🙂

@EgorBo, Are you referring to this, for instance?

runtime/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Byte.cs

Lines 529 to 530 in 3fc8b09

	// Find bitflag offset of first match and add to current offset
	return (int)(offset + (uint)BitOperations.TrailingZeroCount(matches));

no, I meant this: https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/SpanHelpers.Char.cs#L612

I'd defer it to a new PR, due to lack of time on my part.

[EgorBo]

@trympet thanks!

[JulieLeeMSFT]

Thanks @trympet for your first contribution to JIT.

[EgorBo]

I didn't realize I forgot to merge :-)