[clang] [llvm] [HLSL] Implement the `smoothstep` intrinsic (PR #132288)

[Kaitlin Peng via llvm-commits]

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@@ -0,0 +1,60 @@
+; RUN: llc -O0 -verify-machineinstrs -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val %}
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kmpeng wrote:

Seems like this change produces this error in the SPIR-V tests.
```
error: line 1: Capability Kernel is not allowed by Vulkan 1.2 specification (or requires extension)
  OpCapability Kernel
```
Still kind of new to this—do you know what's going on here?

https://github.com/llvm/llvm-project/pull/132288