Add InlineCost class for represent the estimated cost of inlining a

function.
 - This explicitly models the costs for functions which should
   "always" or "never" be inlined. This fixes bugs where such costs
   were not previously respected.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58450 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 40 insertions, 3 deletions

diff --git a/include/llvm/Transforms/IPO/InlinerPass.h b/include/llvm/Transforms/IPO/InlinerPass.h
index 00950f7..082dd82 100644
--- a/include/llvm/Transforms/IPO/InlinerPass.h
+++ b/include/llvm/Transforms/IPO/InlinerPass.h
@@ -18,6 +18,7 @@
 #define INLINER_H
 
 #include "llvm/CallGraphSCCPass.h"
+#include "llvm/Transforms/Utils/InlineCost.h"
 
 namespace llvm {
   class CallSite;
@@ -53,7 +54,7 @@ struct Inliner : public CallGraphSCCPass {
   /// returned is greater than the current inline threshold, the call site is
   /// not inlined.
   ///
-  virtual int getInlineCost(CallSite CS) = 0;
+  virtual InlineCost getInlineCost(CallSite CS) = 0;
 
   // getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
   // higher threshold to determine if the function call should be inlined.
diff --git a/include/llvm/Transforms/Utils/InlineCost.h b/include/llvm/Transforms/Utils/InlineCost.h
index 154ba1a..1698a81 100644
--- a/include/llvm/Transforms/Utils/InlineCost.h
+++ b/include/llvm/Transforms/Utils/InlineCost.h
@@ -15,6 +15,7 @@
 #define LLVM_TRANSFORMS_UTILS_INLINECOST_H
 
 #include "llvm/ADT/SmallPtrSet.h"
+#include <cassert>
 #include <map>
 #include <vector>
 
@@ -24,6 +25,41 @@ namespace llvm {
   class Function;
   class CallSite;
 
+  /// InlineCost - Represent the cost of inlining a function. This
+  /// supports special values for functions which should "always" or
+  /// "never" be inlined. Otherwise, the cost represents a unitless
+  /// amount; smaller values increase the likelyhood of the function
+  /// being inlined.
+  class InlineCost {
+    enum Kind {
+      Value,
+      Always,
+      Never
+    };
+
+    int Cost : 30;
+    unsigned Type :  2;
+
+    InlineCost(int C, int T) : Cost(C), Type(T) {
+      assert(Cost == C && "Cost exceeds InlineCost precision");
+    }
+  public:
+    static InlineCost get(int Cost) { return InlineCost(Cost, Value); }
+    static InlineCost getAlways() { return InlineCost(0, Always); }
+    static InlineCost getNever() { return InlineCost(0, Never); } 
+
+    bool isVariable() const { return Type == Value; }
+    bool isAlways() const { return Type == Always; }
+    bool isNever() const { return Type == Never; }
+
+    /// getValue() - Return a "variable" inline cost's amount. It is
+    /// an error to call this on an "always" or "never" InlineCost.
+    int getValue() const { 
+      assert(Type == Value && "Invalid access of InlineCost");
+      return Cost;
+    }
+  };
+  
   /// InlineCostAnalyzer - Cost analyzer used by inliner.
   class InlineCostAnalyzer {
     struct ArgInfo {
@@ -83,8 +119,8 @@ namespace llvm {
     /// getInlineCost - The heuristic used to determine if we should inline the
     /// function call or not.
     ///
-    int getInlineCost(CallSite CS,
-                      SmallPtrSet<const Function *, 16> &NeverInline);
+    InlineCost getInlineCost(CallSite CS,
+                             SmallPtrSet<const Function *, 16> &NeverInline);
 
     /// getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
     /// higher threshold to determine if the function call should be inlined.