[clang] [llvm] Add length HLSL function to DirectX Backend (PR #101256)

[Farzon Lotfi via cfe-commits]

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@@ -0,0 +1,107 @@
+; RUN: opt -S  -dxil-intrinsic-expansion  < %s | FileCheck %s --check-prefixes=CHECK,EXPCHECK
+; RUN: opt -S  -dxil-op-lower  < %s | FileCheck %s --check-prefixes=CHECK,DOPCHECK
+
+; ModuleID = 'D:\llvm-project\clang\test\CodeGenHLSL\builtins\length.hlsl'
+source_filename = "D:\\llvm-project\\clang\\test\\CodeGenHLSL\\builtins\\length.hlsl"
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farzonl wrote:

That doesn't sound right these are some examples where we doing do it:
- https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/DirectX/clamp.ll
- https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/DirectX/asin.ll

What you need tp do is add  the triple via a flag like so: `-mtriple=dxil-pc-shadermodel6.3-library` 

https://github.com/llvm/llvm-project/pull/101256