Revert "demangle function names in trace files (#87626)"

This reverts commit 0fa20c55b5.

Storing raw symbol names is generally preferred in profile files.
Demangling might lose information. Language frontends might use
demangling schemes not supported by LLVMDemangle
(https://github.com/llvm/llvm-project/issues/45901#issuecomment-2008686663).
In addition, calling `demangle` for each function has a significant
performance overhead (#102222).

I believe that even if we decide to provide a producer-side demangling,
it would not be on by default.

Pull Request: https://github.com/llvm/llvm-project/pull/102274

(cherry picked from commit 72b73e23b6c36537db730ebea00f92798108a6e5)

clang/test/Driver/ftime-trace-sections.py

@@ -19,10 +19,7 @@ def is_before(range1, range2):
 
 log_contents = json.loads(sys.stdin.read())
 events = log_contents["traceEvents"]
-
-instants = [event for event in events if event["name"] == "InstantiateFunction"]
 codegens = [event for event in events if event["name"] == "CodeGen Function"]
-opts = [event for event in events if event["name"] == "OptFunction"]
 frontends = [event for event in events if event["name"] == "Frontend"]
 backends = [event for event in events if event["name"] == "Backend"]
 
@@ -51,11 +48,3 @@ if not all(
     ]
 ):
     sys.exit("Not all Frontend section are before all Backend sections!")
-
-# Check that entries for foo exist and are in a demangled form.
-if not any(e for e in instants if "foo<int>" in e["args"]["detail"]):
-    sys.exit("Missing Instantiate entry for foo!")
-if not any(e for e in codegens if "foo<int>" in e["args"]["detail"]):
-    sys.exit("Missing CodeGen entry for foo!")
-if not any(e for e in opts if "foo<int>" in e["args"]["detail"]):
-    sys.exit("Missing Optimize entry for foo!")

llvm/lib/IR/LegacyPassManager.cpp

@@ -12,7 +12,6 @@
 
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/ADT/MapVector.h"
-#include "llvm/Demangle/Demangle.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
@@ -1416,8 +1415,7 @@ bool FPPassManager::runOnFunction(Function &F) {
 
   // Store name outside of loop to avoid redundant calls.
   const StringRef Name = F.getName();
-  llvm::TimeTraceScope FunctionScope(
-      "OptFunction", [&F]() { return demangle(F.getName().str()); });
+  llvm::TimeTraceScope FunctionScope("OptFunction", Name);
 
   for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
     FunctionPass *FP = getContainedPass(Index);

llvm/lib/Passes/CMakeLists.txt

@@ -21,7 +21,6 @@ add_llvm_component_library(LLVMPasses
   CodeGen
   Core
   Coroutines
-  Demangle
   HipStdPar
   IPO
   InstCombine

llvm/lib/Passes/StandardInstrumentations.cpp

@@ -23,7 +23,6 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineVerifier.h"
-#include "llvm/Demangle/Demangle.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Module.h"
@@ -236,12 +235,12 @@ void printIR(raw_ostream &OS, const MachineFunction *MF) {
   MF->print(OS);
 }
 
-std::string getIRName(Any IR, bool demangled = false) {
+std::string getIRName(Any IR) {
   if (unwrapIR<Module>(IR))
     return "[module]";
 
   if (const auto *F = unwrapIR<Function>(IR))
-    return demangled ? demangle(F->getName()) : F->getName().str();
+    return F->getName().str();
 
   if (const auto *C = unwrapIR<LazyCallGraph::SCC>(IR))
     return C->getName();
@@ -251,7 +250,7 @@ std::string getIRName(Any IR, bool demangled = false) {
            L->getHeader()->getParent()->getName().str();
 
   if (const auto *MF = unwrapIR<MachineFunction>(IR))
-    return demangled ? demangle(MF->getName()) : MF->getName().str();
+    return MF->getName().str();
 
   llvm_unreachable("Unknown wrapped IR type");
 }
@@ -1589,7 +1588,7 @@ void TimeProfilingPassesHandler::registerCallbacks(
 }
 
 void TimeProfilingPassesHandler::runBeforePass(StringRef PassID, Any IR) {
-  timeTraceProfilerBegin(PassID, getIRName(IR, true));
+  timeTraceProfilerBegin(PassID, getIRName(IR));
 }
 
 void TimeProfilingPassesHandler::runAfterPass() { timeTraceProfilerEnd(); }

utils/bazel/llvm-project-overlay/llvm/BUILD.bazel

@@ -2653,7 +2653,6 @@ cc_library(
         ":CodeGen",
         ":Core",
         ":Coroutines",
-        ":Demangle",
         ":HipStdPar",
         ":IPO",
         ":IRPrinter",