Add a few comments.

[oota-llvm.git] / utils / TableGen / RegisterInfoEmitter.cpp

diff --git a/utils/TableGen/RegisterInfoEmitter.cpp b/utils/TableGen/RegisterInfoEmitter.cpp
index 42dccb8eb107d88ce4521063ec1f5114c33471f6..d514bf7deb8fc02e5a7fb0ce9e1725cc9f855dae 100644 (file)
--- a/utils/TableGen/RegisterInfoEmitter.cpp
+++ b/utils/TableGen/RegisterInfoEmitter.cpp
@@ -462,6 +462,82 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
                      RegisterAliases);
     }
   }
+  
+  // Print the SubregHashTable, a simple quadratically probed
+  // hash table for determining if a register is a subregister
+  // of another register.
+  unsigned NumSubRegs = 0;
+  std::map<Record*, unsigned> RegNo;
+  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
+    RegNo[Regs[i].TheDef] = i;
+    NumSubRegs += RegisterSubRegs[Regs[i].TheDef].size();
+  }
+  
+  unsigned SubregHashTableSize = 2 * NextPowerOf2(2 * NumSubRegs);
+  unsigned* SubregHashTable = new unsigned[2 * SubregHashTableSize];
+  std::fill(SubregHashTable, SubregHashTable + 2 * SubregHashTableSize, ~0U);
+  
+  unsigned hashMisses = 0;
+  
+  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
+    Record* R = Regs[i].TheDef;
+    for (std::set<Record*>::iterator I = RegisterSubRegs[R].begin(),
+         E = RegisterSubRegs[R].end(); I != E; ++I) {
+      Record* RJ = *I;
+      // We have to increase the indices of both registers by one when
+      // computing the hash because, in the generated code, there
+      // will be an extra empty slot at register 0.
+      size_t index = ((i+1) + (RegNo[RJ]+1) * 37) & (SubregHashTableSize-1);
+      unsigned ProbeAmt = 2;
+      while (SubregHashTable[index*2] != ~0U &&
+             SubregHashTable[index*2+1] != ~0U) {
+        index = (index + ProbeAmt) & (SubregHashTableSize-1);
+        ProbeAmt += 2;
+        
+        hashMisses++;
+      }
+      
+      SubregHashTable[index*2] = i;
+      SubregHashTable[index*2+1] = RegNo[RJ];
+    }
+  }
+  
+  OS << "\n\n  // Number of hash collisions: " << hashMisses << "\n";
+  
+  if (SubregHashTableSize) {
+    std::string Namespace = Regs[0].TheDef->getValueAsString("Namespace");
+    
+    OS << "  const unsigned SubregHashTable[] = { ";
+    for (unsigned i = 0; i < SubregHashTableSize - 1; ++i) {
+      if (i != 0)
+        // Insert spaces for nice formatting.
+        OS << "                                       ";
+      
+      if (SubregHashTable[2*i] != ~0U) {
+        OS << getQualifiedName(Regs[SubregHashTable[2*i]].TheDef) << ", "
+           << getQualifiedName(Regs[SubregHashTable[2*i+1]].TheDef) << ", \n";
+      } else {
+        OS << Namespace << "::NoRegister, " << Namespace << "::NoRegister, \n";
+      }
+    }
+    
+    unsigned Idx = SubregHashTableSize*2-2;
+    if (SubregHashTable[Idx] != ~0U) {
+      OS << "                                       "
+         << getQualifiedName(Regs[SubregHashTable[Idx]].TheDef) << ", "
+         << getQualifiedName(Regs[SubregHashTable[Idx+1]].TheDef) << " };\n";
+    } else {
+      OS << Namespace << "::NoRegister, " << Namespace << "::NoRegister };\n";
+    }
+    
+    OS << "  const unsigned SubregHashTableSize = "
+       << SubregHashTableSize << ";\n";
+  } else {
+    OS << "  const unsigned SubregHashTable[] = { ~0U, ~0U };\n"
+       << "  const unsigned SubregHashTableSize = 1;\n";
+  }
+  
+  delete [] SubregHashTable;
 
   if (!RegisterAliases.empty())
     OS << "\n\n  // Register Alias Sets...\n";
@@ -536,16 +612,7 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
     else
       OS << Reg.getName();
     OS << "\",\t\"";
-    if (!Reg.TheDef->getValueAsString("Name").empty()) {
-      OS << Reg.TheDef->getValueAsString("Name");
-    } else {
-      // Default to "name".
-      if (!Reg.TheDef->getValueAsString("AsmName").empty())
-        OS << Reg.TheDef->getValueAsString("AsmName");
-      else
-        OS << Reg.getName();
-    }
-    OS << "\",\t";
+    OS << Reg.getName() << "\",\t";
     if (RegisterAliases.count(Reg.TheDef))
       OS << Reg.getName() << "_AliasSet,\t";
     else
@@ -607,7 +674,9 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
      << "(int CallFrameSetupOpcode, int CallFrameDestroyOpcode)\n"
      << "  : TargetRegisterInfo(RegisterDescriptors, " << Registers.size()+1
      << ", RegisterClasses, RegisterClasses+" << RegisterClasses.size() <<",\n "
-     << "                 CallFrameSetupOpcode, CallFrameDestroyOpcode) {}\n\n";
+     << "                 CallFrameSetupOpcode, CallFrameDestroyOpcode,\n"
+     << "                 SubregHashTable, SubregHashTableSize) {\n"
+     << "}\n\n";
 
   // Collect all information about dwarf register numbers