[clang] [HLSL] set alwaysinline on HLSL functions (PR #106588)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `clang` at step 6 "test-build-unified-tree-check-clang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/7827

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-clang) failure: test (failure)
******************** TEST 'Clang :: CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: /b/1/llvm-x86_64-debian-dylib/build/bin/clang -cc1 -internal-isystem /b/1/llvm-x86_64-debian-dylib/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.0-compute -emit-llvm -o - -O0 /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl
+ /b/1/llvm-x86_64-debian-dylib/build/bin/clang -cc1 -internal-isystem /b/1/llvm-x86_64-debian-dylib/build/lib/clang/20/include -nostdsysteminc -triple dxil-pc-shadermodel6.0-compute -emit-llvm -o - -O0 /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl
/b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl:14:11: error: CHECK: expected string not found in input
// CHECK: define internal void @"?main@@YAXI at Z"
          ^
<stdin>:1:1: note: scanning from here
; ModuleID = '/b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl'
^
<stdin>:12:1: note: possible intended match here
define void @main() #0 {
^

Input file: <stdin>
Check file: /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            1: ; ModuleID = '/b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl' 
check:14'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
            2: source_filename = "/b/1/llvm-x86_64-debian-dylib/llvm-project/clang/test/CodeGenHLSL/builtins/StructuredBuffer-subscript.hlsl" 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            3: 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" 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            4: target triple = "dxilv1.0-pc-shadermodel6.0-compute" 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            5:  
check:14'0     ~
            6: %"class.hlsl::StructuredBuffer" = type { ptr } 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            7:  
check:14'0     ~
            8: @"?In@@3V?$StructuredBuffer at H@hlsl@@A" = global %"class.hlsl::StructuredBuffer" zeroinitializer, align 4 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            9: @"?Out@@3V?$StructuredBuffer at H@hlsl@@A" = global %"class.hlsl::StructuredBuffer" zeroinitializer, align 4 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           10:  
check:14'0     ~
           11: ; Function Attrs: convergent noinline norecurse 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           12: define void @main() #0 { 
check:14'0     ~~~~~~~~~~~~~~~~~~~~~~~~~
check:14'1     ?                         possible intended match
...

```

</details>

https://github.com/llvm/llvm-project/pull/106588