[clang] [llvm] [AMDGPU] Enable OpenCL hostcall printf (WIP) (PR #72556)

[Matt Arsenault via cfe-commits]

================
@@ -202,12 +207,20 @@ RValue CodeGenFunction::EmitAMDGPUDevicePrintfCallExpr(const CallExpr *E) {
     Args.push_back(Arg);
   }
 
-  llvm::IRBuilder<> IRB(Builder.GetInsertBlock(), Builder.GetInsertPoint());
-  IRB.SetCurrentDebugLocation(Builder.getCurrentDebugLocation());
+  auto PFK = CGM.getTarget().getTargetOpts().AMDGPUPrintfKindVal;
+  bool isBuffered = (PFK == clang::TargetOptions::AMDGPUPrintfKind::Buffered);
+
+  StringRef FmtStr;
+  if (llvm::getConstantStringInfo(Args[0], FmtStr)) {
+    if (FmtStr.empty())
+      FmtStr = StringRef("", 1);
----------------
arsenm wrote:

This is producing an invalid StringRef?

https://github.com/llvm/llvm-project/pull/72556