[clang] Create `hlsl` directory before generating headers into it (PR #188618)

[Deric C. via cfe-commits]

https://github.com/Icohedron created https://github.com/llvm/llvm-project/pull/188618

This PR should fix an issue reported by https://github.com/llvm/llvm-project/pull/187440#issuecomment-4129823619 and https://github.com/llvm/llvm-project/pull/187610#issuecomment-4129976404 where using `clang_generate_header` to generate a header into a directory that did not exist caused an error.

>From bb24de96c7b67fa85ba71880996b1848447a7655 Mon Sep 17 00:00:00 2001
From: Deric Cheung <cheung.deric at gmail.com>
Date: Wed, 25 Mar 2026 14:43:57 -0700
Subject: [PATCH] Create hlsl directory before generating header

---
 clang/lib/Headers/CMakeLists.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/lib/Headers/CMakeLists.txt b/clang/lib/Headers/CMakeLists.txt
index c0a2028e81adc..1335074e5d9f6 100644
--- a/clang/lib/Headers/CMakeLists.txt
+++ b/clang/lib/Headers/CMakeLists.txt
@@ -505,6 +505,7 @@ if(RISCV IN_LIST LLVM_TARGETS_TO_BUILD)
 endif()
 
 # Generate HLSL intrinsic overloads
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/hlsl")
 clang_generate_header(-gen-hlsl-alias-intrinsics HLSLIntrinsics.td
                       hlsl/hlsl_alias_intrinsics_gen.inc)
 clang_generate_header(-gen-hlsl-inline-intrinsics HLSLIntrinsics.td