[RDA] Attempt to make RDA subreg aware

This attempts to make more of RDA aware of potentially overlapping
subregisters. Some of this was already in place, with it iterating
through MCRegUnitIterators. This also replaces calls to
LiveRegs.contains(..) with !LiveRegs.available(..), and updates the
isValidRegUseOf and isValidRegDefOf to search subregs.

Differential Revision: https://reviews.llvm.org/D107351

1 files changed, 30 insertions, 14 deletions

diff --git a/llvm/lib/CodeGen/ReachingDefAnalysis.cpp b/llvm/lib/CodeGen/ReachingDefAnalysis.cpp
index c850571..34e9a2f 100644
--- a/llvm/lib/CodeGen/ReachingDefAnalysis.cpp
+++ b/llvm/lib/CodeGen/ReachingDefAnalysis.cpp
@@ -30,16 +30,32 @@ static bool isValidRegUse(const MachineOperand &MO) {
   return isValidReg(MO) && MO.isUse();
 }
 
-static bool isValidRegUseOf(const MachineOperand &MO, MCRegister PhysReg) {
-  return isValidRegUse(MO) && MO.getReg() == PhysReg;
+static bool isValidRegUseOf(const MachineOperand &MO, MCRegister PhysReg,
+                            const TargetRegisterInfo *TRI) {
+  if (!isValidRegUse(MO))
+    return false;
+  if (MO.getReg() == PhysReg)
+    return true;
+  for (MCRegAliasIterator R(PhysReg, TRI, false); R.isValid(); ++R)
+    if (MO.getReg() == *R)
+      return true;
+  return false;
 }
 
 static bool isValidRegDef(const MachineOperand &MO) {
   return isValidReg(MO) && MO.isDef();
 }
 
-static bool isValidRegDefOf(const MachineOperand &MO, MCRegister PhysReg) {
-  return isValidRegDef(MO) && MO.getReg() == PhysReg;
+static bool isValidRegDefOf(const MachineOperand &MO, MCRegister PhysReg,
+                            const TargetRegisterInfo *TRI) {
+  if (!isValidRegDef(MO))
+    return false;
+  if (MO.getReg() == PhysReg)
+    return true;
+  for (MCRegAliasIterator R(PhysReg, TRI, false); R.isValid(); ++R)
+    if (MO.getReg() == *R)
+      return true;
+  return false;
 }
 
 void ReachingDefAnalysis::enterBasicBlock(MachineBasicBlock *MBB) {
@@ -337,7 +353,7 @@ void ReachingDefAnalysis::getReachingLocalUses(MachineInstr *Def,
       return;
 
     for (auto &MO : MI->operands()) {
-      if (!isValidRegUseOf(MO, PhysReg))
+      if (!isValidRegUseOf(MO, PhysReg, TRI))
         continue;
 
       Uses.insert(&*MI);
@@ -353,7 +369,7 @@ bool ReachingDefAnalysis::getLiveInUses(MachineBasicBlock *MBB,
   for (MachineInstr &MI :
        instructionsWithoutDebug(MBB->instr_begin(), MBB->instr_end())) {
     for (auto &MO : MI.operands()) {
-      if (!isValidRegUseOf(MO, PhysReg))
+      if (!isValidRegUseOf(MO, PhysReg, TRI))
         continue;
       if (getReachingDef(&MI, PhysReg) >= 0)
         return false;
@@ -419,7 +435,7 @@ void ReachingDefAnalysis::getLiveOuts(MachineBasicBlock *MBB,
   VisitedBBs.insert(MBB);
   LivePhysRegs LiveRegs(*TRI);
   LiveRegs.addLiveOuts(*MBB);
-  if (!LiveRegs.contains(PhysReg))
+  if (LiveRegs.available(MBB->getParent()->getRegInfo(), PhysReg))
     return;
 
   if (auto *Def = getLocalLiveOutMIDef(MBB, PhysReg))
@@ -469,7 +485,7 @@ bool ReachingDefAnalysis::isRegUsedAfter(MachineInstr *MI,
   LiveRegs.addLiveOuts(*MBB);
 
   // Yes if the register is live out of the basic block.
-  if (LiveRegs.contains(PhysReg))
+  if (!LiveRegs.available(MBB->getParent()->getRegInfo(), PhysReg))
     return true;
 
   // Walk backwards through the block to see if the register is live at some
@@ -477,7 +493,7 @@ bool ReachingDefAnalysis::isRegUsedAfter(MachineInstr *MI,
   for (MachineInstr &Last :
        instructionsWithoutDebug(MBB->instr_rbegin(), MBB->instr_rend())) {
     LiveRegs.stepBackward(Last);
-    if (LiveRegs.contains(PhysReg))
+    if (!LiveRegs.available(MBB->getParent()->getRegInfo(), PhysReg))
       return InstIds.lookup(&Last) > InstIds.lookup(MI);
   }
   return false;
@@ -502,7 +518,7 @@ bool ReachingDefAnalysis::isReachingDefLiveOut(MachineInstr *MI,
   MachineBasicBlock *MBB = MI->getParent();
   LivePhysRegs LiveRegs(*TRI);
   LiveRegs.addLiveOuts(*MBB);
-  if (!LiveRegs.contains(PhysReg))
+  if (LiveRegs.available(MBB->getParent()->getRegInfo(), PhysReg))
     return false;
 
   auto Last = MBB->getLastNonDebugInstr();
@@ -512,7 +528,7 @@ bool ReachingDefAnalysis::isReachingDefLiveOut(MachineInstr *MI,
 
   // Finally check that the last instruction doesn't redefine the register.
   for (auto &MO : Last->operands())
-    if (isValidRegDefOf(MO, PhysReg))
+    if (isValidRegDefOf(MO, PhysReg, TRI))
       return false;
 
   return true;
@@ -523,7 +539,7 @@ ReachingDefAnalysis::getLocalLiveOutMIDef(MachineBasicBlock *MBB,
                                           MCRegister PhysReg) const {
   LivePhysRegs LiveRegs(*TRI);
   LiveRegs.addLiveOuts(*MBB);
-  if (!LiveRegs.contains(PhysReg))
+  if (LiveRegs.available(MBB->getParent()->getRegInfo(), PhysReg))
     return nullptr;
 
   auto Last = MBB->getLastNonDebugInstr();
@@ -532,7 +548,7 @@ ReachingDefAnalysis::getLocalLiveOutMIDef(MachineBasicBlock *MBB,
 
   int Def = getReachingDef(&*Last, PhysReg);
   for (auto &MO : Last->operands())
-    if (isValidRegDefOf(MO, PhysReg))
+    if (isValidRegDefOf(MO, PhysReg, TRI))
       return &*Last;
 
   return Def < 0 ? nullptr : getInstFromId(MBB, Def);
@@ -700,7 +716,7 @@ bool ReachingDefAnalysis::isSafeToDefRegAt(MachineInstr *MI, MCRegister PhysReg,
       if (Ignore.count(&*I))
         continue;
       for (auto &MO : I->operands())
-        if (isValidRegDefOf(MO, PhysReg))
+        if (isValidRegDefOf(MO, PhysReg, TRI))
           return false;
     }
   }