[llvm] [llvm][rtsan] Add transform pass for sanitize_realtime_unsafe (PR #109543)

[via llvm-commits]

================
@@ -17,47 +17,75 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Module.h"
 
+#include "llvm/Demangle/Demangle.h"
 #include "llvm/Transforms/Instrumentation/RealtimeSanitizer.h"
 
 using namespace llvm;
 
+static SmallVector<Type *> getArgTypes(ArrayRef<Value *> FunctionArgs) {
+  SmallVector<Type *> Types;
+  for (Value *Arg : FunctionArgs)
+    Types.push_back(Arg->getType());
+  return Types;
+}
+
 static void insertCallBeforeInstruction(Function &Fn, Instruction &Instruction,
-                                        const char *FunctionName) {
+                                        const char *FunctionName,
+                                        ArrayRef<Value *> FunctionArgs) {
   LLVMContext &Context = Fn.getContext();
-  FunctionType *FuncType = FunctionType::get(Type::getVoidTy(Context), false);
+  FunctionType *FuncType = FunctionType::get(Type::getVoidTy(Context),
+                                             getArgTypes(FunctionArgs), false);
   FunctionCallee Func =
       Fn.getParent()->getOrInsertFunction(FunctionName, FuncType);
   IRBuilder<> Builder{&Instruction};
-  Builder.CreateCall(Func, {});
+  Builder.CreateCall(Func, FunctionArgs);
 }
 
 static void insertCallAtFunctionEntryPoint(Function &Fn,
-                                           const char *InsertFnName) {
-
-  insertCallBeforeInstruction(Fn, Fn.front().front(), InsertFnName);
+                                           const char *InsertFnName,
+                                           ArrayRef<Value *> FunctionArgs) {
+  insertCallBeforeInstruction(Fn, Fn.front().front(), InsertFnName,
+                              FunctionArgs);
 }
 
 static void insertCallAtAllFunctionExitPoints(Function &Fn,
-                                              const char *InsertFnName) {
+                                              const char *InsertFnName,
+                                              ArrayRef<Value *> FunctionArgs) {
   for (auto &BB : Fn)
     for (auto &I : BB)
       if (isa<ReturnInst>(&I))
-        insertCallBeforeInstruction(Fn, I, InsertFnName);
+        insertCallBeforeInstruction(Fn, I, InsertFnName, FunctionArgs);
+}
+
+static PreservedAnalyses rtsanPreservedCFGAnalyses() {
+  PreservedAnalyses PA;
+  PA.preserveSet<CFGAnalyses>();
+  return PA;
+}
+
+static PreservedAnalyses runSanitizeRealtime(Function &Fn) {
+  insertCallAtFunctionEntryPoint(Fn, "__rtsan_realtime_enter", {});
+  insertCallAtAllFunctionExitPoints(Fn, "__rtsan_realtime_exit", {});
+  return rtsanPreservedCFGAnalyses();
+}
+
+static PreservedAnalyses runSanitizeRealtimeUnsafe(Function &Fn) {
+  IRBuilder<> Builder(&Fn.front().front());
+  Value *Name = Builder.CreateGlobalString(demangle(Fn.getName()));
----------------
davidtrevelyan wrote:

That's a really great question. In all honesty I didn't originally think about the possibility of de-mangling during the report stage. After thinking about it further, I have an idea on which one will probably be less work overall, but I'd need advice on whether the distribution of work is appropriate.

Here's how I see the work involved:

- for demangling in the pass:
   - no run-time work: demangles once at compile time, but
   - could increase compile-time work (marginally?)
 - for demangling in the reporting:
   - adds to run-time work: demangles every time an error is registered (which could be many times if `halt_on_error` is off)
   - won't add to compile-time work 
   
 My very naive intuition is that demangling in the pass is preferable, but very happy to move it to the reporting if I have my priorities a bit upside down. Thanks in advance for any suggestions here.

https://github.com/llvm/llvm-project/pull/109543