RegAlloc superpass: includes phi elimination, coalescing, and scheduling.

[oota-llvm.git] / lib / CodeGen / LiveVariables.cpp

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 96d36c8e56a1c44a12a9f243f847f7b8d928b03a..7d98935a7e632fde3d95fca76919ccb76404aa62 100644 (file)
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallSet.h"
@@ -41,6 +42,7 @@
 using namespace llvm;
 
 char LiveVariables::ID = 0;
+char &llvm::LiveVariablesID = LiveVariables::ID;
 INITIALIZE_PASS_BEGIN(LiveVariables, "livevars",
                 "Live Variable Analysis", false, false)
 INITIALIZE_PASS_DEPENDENCY(UnreachableMachineBlockElim)
@@ -90,7 +92,7 @@ void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo,
                                             MachineBasicBlock *MBB,
                                     std::vector<MachineBasicBlock*> &WorkList) {
   unsigned BBNum = MBB->getNumber();
-  
+
   // Check to see if this basic block is one of the killing blocks.  If so,
   // remove it.
   for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i)
@@ -98,7 +100,7 @@ void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo,
       VRInfo.Kills.erase(VRInfo.Kills.begin()+i);  // Erase entry
       break;
     }
-  
+
   if (MBB == DefBlock) return;  // Terminate recursion
 
   if (VRInfo.AliveBlocks.test(BBNum))
@@ -130,7 +132,6 @@ void LiveVariables::HandleVirtRegUse(unsigned reg, MachineBasicBlock *MBB,
   unsigned BBNum = MBB->getNumber();
 
   VarInfo& VRInfo = getVarInfo(reg);
-  VRInfo.NumUses++;
 
   // Check to see if this basic block is already a kill block.
   if (!VRInfo.Kills.empty() && VRInfo.Kills.back()->getParent() == MBB) {
@@ -330,7 +331,7 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
   // Or whole register is defined, but only partly used.
   // AX<dead> = AL<imp-def>
   //    = AL<kill>
-  // AX = 
+  // AX =
   MachineInstr *LastPartDef = 0;
   unsigned LastPartDefDist = 0;
   SmallSet<unsigned, 8> PartUses;
@@ -418,6 +419,27 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
   return true;
 }
 
+void LiveVariables::HandleRegMask(const MachineOperand &MO) {
+  // Call HandlePhysRegKill() for all live registers clobbered by Mask.
+  // Clobbered registers are always dead, sp there is no need to use
+  // HandlePhysRegDef().
+  for (unsigned Reg = 1, NumRegs = TRI->getNumRegs(); Reg != NumRegs; ++Reg) {
+    // Skip dead regs.
+    if (!PhysRegDef[Reg] && !PhysRegUse[Reg])
+      continue;
+    // Skip mask-preserved regs.
+    if (!MO.clobbersPhysReg(Reg))
+      continue;
+    // Kill the largest clobbered super-register.
+    // This avoids needless implicit operands.
+    unsigned Super = Reg;
+    for (const unsigned *SR = TRI->getSuperRegisters(Reg); *SR; ++SR)
+      if ((PhysRegDef[*SR] || PhysRegUse[*SR]) && MO.clobbersPhysReg(*SR))
+        Super = *SR;
+    HandlePhysRegKill(Super, 0);
+  }
+}
+
 void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI,
                                      SmallVector<unsigned, 4> &Defs) {
   // What parts of the register are previously defined?
@@ -491,6 +513,12 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
   std::fill(PhysRegUse,  PhysRegUse  + NumRegs, (MachineInstr*)0);
   PHIJoins.clear();
 
+  // FIXME: LiveIntervals will be updated to remove its dependence on
+  // LiveVariables to improve compilation time and eliminate bizarre pass
+  // dependencies. Until then, we can't change much in -O0.
+  if (!MRI->isSSA())
+    report_fatal_error("regalloc=... not currently supported with -O0");
+
   analyzePHINodes(mf);
 
   // Calculate live variable information in depth first order on the CFG of the
@@ -535,8 +563,13 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
       // Clear kill and dead markers. LV will recompute them.
       SmallVector<unsigned, 4> UseRegs;
       SmallVector<unsigned, 4> DefRegs;
+      SmallVector<unsigned, 1> RegMasks;
       for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
         MachineOperand &MO = MI->getOperand(i);
+        if (MO.isRegMask()) {
+          RegMasks.push_back(i);
+          continue;
+        }
         if (!MO.isReg() || MO.getReg() == 0)
           continue;
         unsigned MOReg = MO.getReg();
@@ -558,6 +591,10 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
           HandlePhysRegUse(MOReg, MI);
       }
 
+      // Process all masked registers. (Call clobbers).
+      for (unsigned i = 0, e = RegMasks.size(); i != e; ++i)
+        HandleRegMask(MI->getOperand(RegMasks[i]));
+
       // Process all defs.
       for (unsigned i = 0, e = DefRegs.size(); i != e; ++i) {
         unsigned MOReg = DefRegs[i];