optimize FastISel::UpdateValueMap to avoid duplicate map lookups,

and make it return the assigned register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68888 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/FastISel.h b/include/llvm/CodeGen/FastISel.h
index 085810aaf116cae2d6e9b4f25754df00a1feccd5..8c23058c3d1d23047ecab9fc6a052c9e92e7ebc2 100644 (file)
--- a/include/llvm/CodeGen/FastISel.h
+++ b/include/llvm/CodeGen/FastISel.h
@@ -279,7 +279,7 @@ protected:
   /// the CFG.
   void FastEmitBranch(MachineBasicBlock *MBB);
 
-  void UpdateValueMap(Value* I, unsigned Reg);
+  unsigned UpdateValueMap(Value* I, unsigned Reg);
 
   unsigned createResultReg(const TargetRegisterClass *RC);
   

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index 8467330bb9b2f4e8d16da985b559906e0d6b5916..7e300536748df60c1647e5ca7f5e7f57a66a34f8 100644 (file)
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -149,16 +149,21 @@ unsigned FastISel::lookUpRegForValue(Value *V) {
 /// NOTE: This is only necessary because we might select a block that uses
 /// a value before we select the block that defines the value.  It might be
 /// possible to fix this by selecting blocks in reverse postorder.
-void FastISel::UpdateValueMap(Value* I, unsigned Reg) {
+unsigned FastISel::UpdateValueMap(Value* I, unsigned Reg) {
   if (!isa<Instruction>(I)) {
     LocalValueMap[I] = Reg;
-    return;
+    return Reg;
+  }
+  
+  unsigned &AssignedReg = ValueMap[I];
+  if (AssignedReg == 0)
+    AssignedReg = Reg;
+  else {
+    const TargetRegisterClass *RegClass = MRI.getRegClass(Reg);
+    TII.copyRegToReg(*MBB, MBB->end(), AssignedReg,
+                     Reg, RegClass, RegClass);
   }
-  if (!ValueMap.count(I))
-    ValueMap[I] = Reg;
-  else
-    TII.copyRegToReg(*MBB, MBB->end(), ValueMap[I],
-                     Reg, MRI.getRegClass(Reg), MRI.getRegClass(Reg));
+  return AssignedReg;
 }
 
 unsigned FastISel::getRegForGEPIndex(Value *Idx) {