From accfde3ad612bb30e426b1bc13760549a28fd9df Mon Sep 17 00:00:00 2001
From: Mehdi Amini <mehdi.amini@apple.com>
Date: Wed, 2 Dec 2015 04:34:28 +0000
Subject: [PATCH] Change ModuleLinker to take a set of GlobalValues to import
 instead of a single one

For efficiency reason, when importing multiple functions for the same Module,
we can avoid reparsing it every time.

Differential Revision: http://reviews.llvm.org/D15102

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254486 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Linker/Linker.h          |  2 +-
 lib/Linker/LinkModules.cpp            | 10 +++++-----
 lib/Transforms/IPO/FunctionImport.cpp |  6 +++++-
 tools/llvm-link/llvm-link.cpp         |  5 ++++-
 4 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/include/llvm/Linker/Linker.h b/include/llvm/Linker/Linker.h
index 38fa5562f30..7c24eef7411 100644
--- a/include/llvm/Linker/Linker.h
+++ b/include/llvm/Linker/Linker.h
@@ -82,7 +82,7 @@ public:
   /// Returns true on error.
   bool linkInModule(Module &Src, unsigned Flags = Flags::None,
                     const FunctionInfoIndex *Index = nullptr,
-                    Function *FuncToImport = nullptr);
+                    DenseSet<const GlobalValue *> *FuncToImport = nullptr);
 
   static bool linkModules(Module &Dest, Module &Src,
                           DiagnosticHandlerFunction DiagnosticHandler,
diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index 39ab5db8d6b..fba231100ee 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -406,7 +406,7 @@ class ModuleLinker {
 
   /// Function to import from source module, all other functions are
   /// imported as declarations instead of definitions.
-  Function *ImportFunction;
+  DenseSet<const GlobalValue *> *ImportFunction;
 
   /// Set to true if the given FunctionInfoIndex contains any functions
   /// from this source module, in which case we must conservatively assume
@@ -425,7 +425,7 @@ public:
   ModuleLinker(Module &DstM, Linker::IdentifiedStructTypeSet &Set, Module &SrcM,
                DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
                const FunctionInfoIndex *Index = nullptr,
-               Function *FuncToImport = nullptr)
+               DenseSet<const GlobalValue *> *FuncToImport = nullptr)
       : DstM(DstM), SrcM(SrcM), TypeMap(Set), ValMaterializer(this),
         DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
         ImportFunction(FuncToImport) {
@@ -632,7 +632,7 @@ bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
     return true;
   // Only import the function requested for importing.
   auto *SF = dyn_cast<Function>(SGV);
-  if (SF && SF == ImportFunction)
+  if (SF && ImportFunction->count(SF))
     return true;
   // Otherwise no.
   return false;
@@ -1058,7 +1058,7 @@ bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
     if (isa<Function>(&Src)) {
       // For functions, LinkFromSrc iff this is the function requested
       // for importing. For variables, decide below normally.
-      LinkFromSrc = (&Src == ImportFunction);
+      LinkFromSrc = ImportFunction->count(&Src);
       return false;
     }
 
@@ -2033,7 +2033,7 @@ Linker::Linker(Module &M)
 
 bool Linker::linkInModule(Module &Src, unsigned Flags,
                           const FunctionInfoIndex *Index,
-                          Function *FuncToImport) {
+                          DenseSet<const GlobalValue *> *FuncToImport) {
   ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
                          DiagnosticHandler, Flags, Index, FuncToImport);
   bool RetCode = TheLinker.run();
diff --git a/lib/Transforms/IPO/FunctionImport.cpp b/lib/Transforms/IPO/FunctionImport.cpp
index 92764c9e8c3..8230d64026c 100644
--- a/lib/Transforms/IPO/FunctionImport.cpp
+++ b/lib/Transforms/IPO/FunctionImport.cpp
@@ -182,7 +182,10 @@ bool FunctionImporter::importFunctions(Module &M) {
     }
 
     // Link in the specified function.
-    if (L.linkInModule(Module, Linker::Flags::None, &Index, F))
+    DenseSet<const GlobalValue *> FunctionsToImport;
+    FunctionsToImport.insert(F);
+    if (L.linkInModule(Module, Linker::Flags::None, &Index,
+                       &FunctionsToImport))
       report_fatal_error("Function Import: link error");
 
     // Process the newly imported function and add callees to the worklist.
@@ -194,6 +197,7 @@ bool FunctionImporter::importFunctions(Module &M) {
 
     Changed = true;
   }
+
   return Changed;
 }
 
diff --git a/tools/llvm-link/llvm-link.cpp b/tools/llvm-link/llvm-link.cpp
index 2b63649cec2..9a373c25cc5 100644
--- a/tools/llvm-link/llvm-link.cpp
+++ b/tools/llvm-link/llvm-link.cpp
@@ -198,7 +198,10 @@ static bool importFunctions(const char *argv0, LLVMContext &Context,
     }
 
     // Link in the specified function.
-    if (L.linkInModule(*M, Linker::Flags::None, Index.get(), F))
+    DenseSet<const GlobalValue *> FunctionToImport;
+    FunctionToImport.insert(F);
+    if (L.linkInModule(*M, Linker::Flags::None, Index.get(),
+                       &FunctionToImport))
       return false;
   }
   return true;
-- 
2.34.1