[llvm-commits] [llvm] r148589 - /llvm/trunk/lib/CodeGen/MachineLICM.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Fri Jan 20 16:27:12 2012
New Revision: 148589

URL: http://llvm.org/viewvc/llvm-project?rev=148589&view=rev
Log:
Support register masks in MachineLICM.

Only PostRA LICM is affected.

Modified:
    llvm/trunk/lib/CodeGen/MachineLICM.cpp

Modified: llvm/trunk/lib/CodeGen/MachineLICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineLICM.cpp?rev=148589&r1=148588&r2=148589&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineLICM.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineLICM.cpp Fri Jan 20 16:27:12 2012
@@ -163,7 +163,9 @@
 
     /// ProcessMI - Examine the instruction for potentai LICM candidate. Also
     /// gather register def and frame object update information.
-    void ProcessMI(MachineInstr *MI, unsigned *PhysRegDefs,
+    void ProcessMI(MachineInstr *MI,
+                   BitVector &PhysRegDefs,
+                   BitVector &PhysRegClobbers,
                    SmallSet<int, 32> &StoredFIs,
                    SmallVector<CandidateInfo, 32> &Candidates);
 
@@ -392,7 +394,8 @@
 /// ProcessMI - Examine the instruction for potentai LICM candidate. Also
 /// gather register def and frame object update information.
 void MachineLICM::ProcessMI(MachineInstr *MI,
-                            unsigned *PhysRegDefs,
+                            BitVector &PhysRegDefs,
+                            BitVector &PhysRegClobbers,
                             SmallSet<int, 32> &StoredFIs,
                             SmallVector<CandidateInfo, 32> &Candidates) {
   bool RuledOut = false;
@@ -411,6 +414,16 @@
       continue;
     }
 
+    // We can't hoist an instruction defining a physreg that is clobbered in
+    // the loop.
+    if (MO.isRegMask()) {
+      if (const uint32_t *Mask = MO.getRegMask())
+        PhysRegClobbers.setBitsNotInMask(Mask);
+      else
+        PhysRegClobbers.set();
+      continue;
+    }
+
     if (!MO.isReg())
       continue;
     unsigned Reg = MO.getReg();
@@ -420,7 +433,7 @@
            "Not expecting virtual register!");
 
     if (!MO.isDef()) {
-      if (Reg && PhysRegDefs[Reg])
+      if (Reg && (PhysRegDefs.test(Reg) || PhysRegClobbers.test(Reg)))
         // If it's using a non-loop-invariant register, then it's obviously not
         // safe to hoist.
         HasNonInvariantUse = true;
@@ -428,9 +441,8 @@
     }
 
     if (MO.isImplicit()) {
-      ++PhysRegDefs[Reg];
-      for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
-        ++PhysRegDefs[*AS];
+      for (const unsigned *AS = TRI->getOverlaps(Reg); *AS; ++AS)
+        PhysRegClobbers.set(*AS);
       if (!MO.isDead())
         // Non-dead implicit def? This cannot be hoisted.
         RuledOut = true;
@@ -447,14 +459,17 @@
       Def = Reg;
 
     // If we have already seen another instruction that defines the same
-    // register, then this is not safe.
-    if (++PhysRegDefs[Reg] > 1)
-      // MI defined register is seen defined by another instruction in
-      // the loop, it cannot be a LICM candidate.
-      RuledOut = true;
-    for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
-      if (++PhysRegDefs[*AS] > 1)
+    // register, then this is not safe.  Two defs is indicated by setting a
+    // PhysRegClobbers bit.
+    for (const unsigned *AS = TRI->getOverlaps(Reg); *AS; ++AS) {
+      if (PhysRegDefs.test(Reg))
+        PhysRegClobbers.set(Reg);
+      if (PhysRegClobbers.test(Reg))
+        // MI defined register is seen defined by another instruction in
+        // the loop, it cannot be a LICM candidate.
         RuledOut = true;
+      PhysRegDefs.set(Reg);
+    }
   }
 
   // Only consider reloads for now and remats which do not have register
@@ -471,8 +486,8 @@
 /// invariants out to the preheader.
 void MachineLICM::HoistRegionPostRA() {
   unsigned NumRegs = TRI->getNumRegs();
-  unsigned *PhysRegDefs = new unsigned[NumRegs];
-  std::fill(PhysRegDefs, PhysRegDefs + NumRegs, 0);
+  BitVector PhysRegDefs(NumRegs); // Regs defined once in the loop.
+  BitVector PhysRegClobbers(NumRegs); // Regs defined more than once.
 
   SmallVector<CandidateInfo, 32> Candidates;
   SmallSet<int, 32> StoredFIs;
@@ -494,16 +509,15 @@
     for (MachineBasicBlock::livein_iterator I = BB->livein_begin(),
            E = BB->livein_end(); I != E; ++I) {
       unsigned Reg = *I;
-      ++PhysRegDefs[Reg];
-      for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
-        ++PhysRegDefs[*AS];
+      for (const unsigned *AS = TRI->getOverlaps(Reg); *AS; ++AS)
+        PhysRegDefs.set(*AS);
     }
 
     SpeculationState = SpeculateUnknown;
     for (MachineBasicBlock::iterator
            MII = BB->begin(), E = BB->end(); MII != E; ++MII) {
       MachineInstr *MI = &*MII;
-      ProcessMI(MI, PhysRegDefs, StoredFIs, Candidates);
+      ProcessMI(MI, PhysRegDefs, PhysRegClobbers, StoredFIs, Candidates);
     }
   }
 
@@ -517,14 +531,15 @@
         StoredFIs.count(Candidates[i].FI))
       continue;
 
-    if (PhysRegDefs[Candidates[i].Def] == 1) {
+    if (!PhysRegClobbers.test(Candidates[i].Def)) {
       bool Safe = true;
       MachineInstr *MI = Candidates[i].MI;
       for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
         const MachineOperand &MO = MI->getOperand(j);
         if (!MO.isReg() || MO.isDef() || !MO.getReg())
           continue;
-        if (PhysRegDefs[MO.getReg()]) {
+        if (PhysRegDefs.test(MO.getReg()) ||
+            PhysRegClobbers.test(MO.getReg())) {
           // If it's using a non-loop-invariant register, then it's obviously
           // not safe to hoist.
           Safe = false;
@@ -535,8 +550,6 @@
         HoistPostRA(MI, Candidates[i].Def);
     }
   }
-
-  delete[] PhysRegDefs;
 }
 
 /// AddToLiveIns - Add register 'Reg' to the livein sets of BBs in the current