[PATCH] D13631: [JIT/llvm-rtdyld] Don't waste cycles invalidating the Instruction cache

[Davide Italiano via llvm-commits]

davide removed rL LLVM as the repository for this revision.
davide updated this revision to Diff 38832.
davide added a comment.

Updated after our discussion on IRC. Thanks!


http://reviews.llvm.org/D13631

Files:
  lib/Support/Unix/Memory.inc
  tools/llvm-rtdyld/llvm-rtdyld.cpp

Index: tools/llvm-rtdyld/llvm-rtdyld.cpp
===================================================================
--- tools/llvm-rtdyld/llvm-rtdyld.cpp
+++ tools/llvm-rtdyld/llvm-rtdyld.cpp
@@ -155,12 +155,6 @@
 
   bool finalizeMemory(std::string *ErrMsg) override { return false; }
 
-  // Invalidate instruction cache for sections with execute permissions.
-  // Some platforms with separate data cache and instruction cache require
-  // explicit cache flush, otherwise JIT code manipulations (like resolved
-  // relocations) will get to the data cache but not to the instruction cache.
-  virtual void invalidateInstructionCache();
-
   void addDummySymbol(const std::string &Name, uint64_t Addr) {
     DummyExterns[Name] = Addr;
   }
@@ -244,14 +238,6 @@
   return (uint8_t*)MB.base();
 }
 
-void TrivialMemoryManager::invalidateInstructionCache() {
-  for (auto &FM : FunctionMemory)
-    sys::Memory::InvalidateInstructionCache(FM.base(), FM.size());
-
-  for (auto &DM : DataMemory)
-    sys::Memory::InvalidateInstructionCache(DM.base(), DM.size());
-}
-
 static const char *ProgramName;
 
 static void Message(const char *Type, const Twine &Msg) {
@@ -424,26 +410,26 @@
     }
   }
 
-  // Resolve all the relocations we can.
-  Dyld.resolveRelocations();
-  // Clear instruction cache before code will be executed.
-  MemMgr.invalidateInstructionCache();
-
+  // Resove all the relocations we can.
   // FIXME: Error out if there are unresolved relocations.
+  Dyld.resolveRelocations();
 
   // Get the address of the entry point (_main by default).
   void *MainAddress = Dyld.getSymbolLocalAddress(EntryPoint);
   if (!MainAddress)
     return Error("no definition for '" + EntryPoint + "'");
 
   // Invalidate the instruction cache for each loaded function.
   for (auto &FM : MemMgr.FunctionMemory) {
+
     // Make sure the memory is executable.
+    // setExecutable will call InvalidateInstructionCache.
     std::string ErrorStr;
-    sys::Memory::InvalidateInstructionCache(FM.base(), FM.size());
     if (!sys::Memory::setExecutable(FM, &ErrorStr))
       return Error("unable to mark function executable: '" + ErrorStr + "'");
   }
+  for (auto &DM : MemMgr.DataMemory)
+    sys::Memory::InvalidateInstructionCache(DM.base(), DM.size());
 
   // Dispatch to _main().
   errs() << "loaded '" << EntryPoint << "' at: " << (void*)MainAddress << "\n";
Index: lib/Support/Unix/Memory.inc
===================================================================
--- lib/Support/Unix/Memory.inc
+++ lib/Support/Unix/Memory.inc
@@ -264,15 +264,12 @@
 }
 
 bool Memory::setExecutable (MemoryBlock &M, std::string *ErrMsg) {
-#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
   if (M.Address == 0 || M.Size == 0) return false;
   Memory::InvalidateInstructionCache(M.Address, M.Size);
+#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
   kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
     (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
   return KERN_SUCCESS == kr;
-#elif defined(__arm__) || defined(__aarch64__)
-  Memory::InvalidateInstructionCache(M.Address, M.Size);
-  return true;
 #else
   return true;
 #endif


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