[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"
+target datalayout = "e-m:e-p:32:32-i1:32-i8:8-i16:16-i32:32-i64:64-f16:16-f32:32-f64:64-n8:16:32:64"
+target triple = "dxilv1.3-pc-shadermodel6.3-library"
+
+; Function Attrs: convergent noinline nounwind optnone
+define noundef float @"?test_length_half@@YA$halff@$halff@@Z"(float noundef %p0) #0 {
+entry:
+  %p0.addr = alloca float, align 4
+  store float %p0, ptr %p0.addr, align 4
+  %0 = load float, ptr %p0.addr, align 4
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farzonl wrote:

remove lines 12-14 just pass the value `p0` to `@llvm.fabs.f32`

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