From: Owen Anderson <resistor@mac.com>
Date: Thu, 14 Aug 2008 18:34:18 +0000 (+0000)
Subject: Speed up addRegisterDead by adding more fast checks before performing the expensive
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=22ae99908258dd5631fde7128a94c418ed08eae5;p=oota-llvm.git

Speed up addRegisterDead by adding more fast checks before performing the expensive
subregister query, and by increasing the size of the subregister hashtable so
that there are fewer collisions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54781 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index c952293976e..d602e2442f7 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -834,7 +834,9 @@ bool MachineInstr::addRegisterDead(unsigned IncomingReg,
       // There exists a super-register that's marked dead.
       if (RegInfo->isSuperRegister(IncomingReg, Reg))
         return true;
-      if (RegInfo->isSubRegister(IncomingReg, Reg))
+      if (RegInfo->getSubRegisters(IncomingReg) &&
+          RegInfo->getSuperRegisters(Reg) &&
+          RegInfo->isSubRegister(IncomingReg, Reg))
         DeadOps.push_back(i);
     }
   }
diff --git a/utils/TableGen/RegisterInfoEmitter.cpp b/utils/TableGen/RegisterInfoEmitter.cpp
index 2870c8038bb..d514bf7deb8 100644
--- a/utils/TableGen/RegisterInfoEmitter.cpp
+++ b/utils/TableGen/RegisterInfoEmitter.cpp
@@ -473,10 +473,12 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
     NumSubRegs += RegisterSubRegs[Regs[i].TheDef].size();
   }
   
-  unsigned SubregHashTableSize = NextPowerOf2(2 * NumSubRegs);
+  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(),
@@ -491,6 +493,8 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
              SubregHashTable[index*2+1] != ~0U) {
         index = (index + ProbeAmt) & (SubregHashTableSize-1);
         ProbeAmt += 2;
+        
+        hashMisses++;
       }
       
       SubregHashTable[index*2] = i;
@@ -498,10 +502,12 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
     }
   }
   
+  OS << "\n\n  // Number of hash collisions: " << hashMisses << "\n";
+  
   if (SubregHashTableSize) {
     std::string Namespace = Regs[0].TheDef->getValueAsString("Namespace");
     
-    OS << "\n\n  const unsigned SubregHashTable[] = { ";
+    OS << "  const unsigned SubregHashTable[] = { ";
     for (unsigned i = 0; i < SubregHashTableSize - 1; ++i) {
       if (i != 0)
         // Insert spaces for nice formatting.
@@ -527,7 +533,7 @@ void RegisterInfoEmitter::run(std::ostream &OS) {
     OS << "  const unsigned SubregHashTableSize = "
        << SubregHashTableSize << ";\n";
   } else {
-    OS << "\n\n  const unsigned SubregHashTable[] = { ~0U, ~0U };\n"
+    OS << "  const unsigned SubregHashTable[] = { ~0U, ~0U };\n"
        << "  const unsigned SubregHashTableSize = 1;\n";
   }