[offload] defer "---> olInit" trace message

Tracing requires liboffload to be initialized, so calling
isTracingEnabled() before olInit always returns false.
This caused the first trace log to look like:

-> OL_SUCCESS

instead of:

---> olInit() -> OL_SUCCESS

This patch moves the pre-call trace print for olInit so it is emitted
only after initialization.

It would be possible to add extra logic to detect whether liboffload
is already initialized and only postpone the first pre-call print, but
this would add unnecessary complexity, especially since this is
tablegen code. The difference would matter only in the unlikely
case of a crash during a second olInit call.

Author: lplewa

offload/tools/offload-tblgen/EntryPointGen.cpp

@@ -83,13 +83,15 @@ static void EmitEntryPointFunc(const FunctionRec &F, raw_ostream &OS) {
   OS << ") {\n";
 
   // Check offload is initialized
-  if (F.getName() != "olInit")
+  if (F.getName() != "olInit") {
     OS << "if (!llvm::offload::isOffloadInitialized()) return &UninitError;";
 
-  // Emit pre-call prints
-  OS << TAB_1 "if (llvm::offload::isTracingEnabled()) {\n";
-  OS << formatv(TAB_2 "llvm::errs() << \"---> {0}\";\n", F.getName());
-  OS << TAB_1 "}\n\n";
+    // Emit pre-call prints
+    // Postpone pre-calls for olInit as tracing requires liboffload to be initialized
+    OS << TAB_1 "if (llvm::offload::isTracingEnabled()) {\n";
+    OS << formatv(TAB_2 "llvm::errs() << \"---> {0}\";\n", F.getName());
+    OS << TAB_1 "}\n\n";
+  }
 
   // Perform actual function call to the validation wrapper
   ParamNameList = ParamNameList.substr(0, ParamNameList.size() - 2);
@@ -99,6 +101,11 @@ static void EmitEntryPointFunc(const FunctionRec &F, raw_ostream &OS) {
 
   // Emit post-call prints
   OS << TAB_1 "if (llvm::offload::isTracingEnabled()) {\n";
+  // postponed pre-call print for olInit
+  if (F.getName() == "olInit") {
+      OS << formatv(TAB_2 "llvm::errs() << \"---> {0}\";\n", F.getName());
+  }
+
   if (F.getParams().size() > 0) {
     OS << formatv(TAB_2 "{0} Params = {{", F.getParamStructName());
     for (const auto &Param : F.getParams()) {