Add custom inliner that handles only functions that are marked as always_inline.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55713 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/InlineAlways.cpp

@@ -0,0 +1,70 @@
+//===- InlineAlways.cpp - Code to perform simple function inlining --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements bottom-up inlining of functions into callees.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "inline"
+#include "llvm/CallingConv.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Module.h"
+#include "llvm/Type.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/InlinerPass.h"
+#include "llvm/Transforms/Utils/InlineCost.h"
+#include "llvm/ADT/SmallPtrSet.h"
+
+using namespace llvm;
+
+namespace {
+
+  // AlwaysInliner only inlines functions that are mark as "always inline".
+  class VISIBILITY_HIDDEN AlwaysInliner : public Inliner {
+    // Functions that are never inlined
+    SmallPtrSet<const Function*, 16> NeverInline; 
+    InlineCostAnalyzer CA;
+  public:
+    // Use extremely low threshold. 
+    AlwaysInliner() : Inliner(&ID, -2000000000) {}
+    static char ID; // Pass identification, replacement for typeid
+    int getInlineCost(CallSite CS) {
+      return CA.getInlineCost(CS, NeverInline);
+    }
+    float getInlineFudgeFactor(CallSite CS) {
+      return CA.getInlineFudgeFactor(CS);
+    }
+    virtual bool doInitialization(CallGraph &CG);
+  };
+}
+
+char AlwaysInliner::ID = 0;
+static RegisterPass<AlwaysInliner>
+X("always-inline", "Inliner that handles always_inline functions");
+
+Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
+
+// doInitialization - Initializes the vector of functions that have not 
+// been annotated with the "always inline" attribute.
+bool AlwaysInliner::doInitialization(CallGraph &CG) {
+  
+  Module &M = CG.getModule();
+  
+  for (Module::iterator I = M.begin(), E = M.end();
+       I != E; ++I)
+    if (!I->isDeclaration() && I->getNotes() != FN_NOTE_AlwaysInline)
+      NeverInline.insert(I);
+
+  return false;
+}
+