[clang] [llvm] [clang][SPIR-V] Implement -fspv-preserve-interface (PR #196404)

[Diego Novillo via cfe-commits]

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@@ -592,6 +593,18 @@ void CGHLSLRuntime::finishCodeGen() {
     M.setModuleFlag(llvm::Module::ModFlagBehavior::Error, "dx.nativelowprec",
                     1);
 
+  if (LangOpts.HLSLSpvPreserveInterface && T.isSPIRV()) {
+    // Runs before optimization. Keeps Input/Output globals from GlobalDCE.
+    SmallVector<GlobalValue *, 8> InterfaceVars;
+    for (GlobalVariable &GV : M.globals()) {
+      unsigned AS = GV.getAddressSpace();
+      if (AS == 7 || AS == 8) // addrspace 7 = Input, addrspace 8 = Output
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dnovillo wrote:

Thanks. I'll take a look.

https://github.com/llvm/llvm-project/pull/196404