[clang] [CIR] Upstream initial function call support (PR #134673)

[Sirui Mu via cfe-commits]

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@@ -466,8 +468,17 @@ CIRGenModule::createCIRFunction(mlir::Location loc, StringRef name,
   {
     mlir::OpBuilder::InsertionGuard guard(builder);
 
+    // Some global emissions are triggered while emitting a function, e.g.
+    // void s() { x.method() }
+    //
+    // Be sure to insert a new function before a current one.
+    if (curCGF)
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Lancern wrote:

I don't see a clear code path that could change `curCGF`, but in case I missed something I updated the code and now it follows the incubator approach.

https://github.com/llvm/llvm-project/pull/134673