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

[Greg Roth via cfe-commits]

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@@ -414,9 +414,20 @@ void CGHLSLRuntime::emitEntryFunction(const FunctionDecl *FD,
 
 void CGHLSLRuntime::setHLSLFunctionAttributes(const FunctionDecl *FD,
                                               llvm::Function *Fn) {
-  if (FD->isInExportDeclContext()) {
-    const StringRef ExportAttrKindStr = "hlsl.export";
-    Fn->addFnAttr(ExportAttrKindStr);
+  if (FD) { // "explicit" functions with declarations
+    if (FD->isInExportDeclContext()) {
+      const StringRef ExportAttrKindStr = "hlsl.export";
+      Fn->addFnAttr(ExportAttrKindStr);
+    }
+    // Respect noinline if the explicit functions use it
+    // otherwise default to alwaysinline
+    if (!Fn->hasFnAttribute(Attribute::NoInline))
+      Fn->addFnAttr(llvm::Attribute::AlwaysInline);
+  } else { // "implicit" autogenerated functions with no declaration
+    // Implicit functions might get marked as noinline by default
+    // but we override that for HLSL
+    Fn->removeFnAttr(Attribute::NoInline);
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pow3clk wrote:

I was trying not to litter too many `if(getLangOpts().HLSL)` conditionals throughout the code. Something similar to this is done in [ a](https://github.com/llvm/llvm-project/blob/3ebd79751f2d5e1c54047409865c051daba0a21b/clang/lib/CodeGen/CGOpenMPRuntime.cpp#L3222-L3224) [few]( https://github.com/llvm/llvm-project/blob/3ebd79751f2d5e1c54047409865c051daba0a21b/clang/lib/CodeGen/CGOpenMPRuntime.cpp#L1100-L1102) [places](https://github.com/llvm/llvm-project/blob/3ebd79751f2d5e1c54047409865c051daba0a21b/clang/lib/CodeGen/CGStmtOpenMP.cpp#L582-L583) for OpenMP. I don't feel strongly about it though. It's trivial to drop an _if HLSL_ conditional there.

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