Use TRI->regsOverlap() in MachineBasicBlock::computeRegisterLiveness

Summary:
For the loop that used MCRegAliasIterator this should be NFC.

For the loop that previously used MCSubRegIterator we should
now detect more cases where the register is actually live out that
we previously missed.

Reviewers: MatzeB, arsenm

Reviewed By: MatzeB

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D52410

llvm-svn: 342944

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 49181e3..6a242d8 100644 (file)
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -1404,9 +1404,8 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
   // no successor has it live in.
   if (I == end()) {
     for (MachineBasicBlock *S : successors()) {
-      for (MCSubRegIterator SubReg(Reg, TRI, /*IncludeSelf*/true);
-           SubReg.isValid(); ++SubReg) {
-        if (S->isLiveIn(*SubReg))
+      for (const MachineBasicBlock::RegisterMaskPair &LI : S->liveins()) {
+        if (TRI->regsOverlap(LI.PhysReg, Reg))
           return LQR_Live;
       }
     }
@@ -1460,9 +1459,8 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
   // Did we get to the start of the block?
   if (I == begin()) {
     // If so, the register's state is definitely defined by the live-in state.
-    for (MCRegAliasIterator RAI(Reg, TRI, /*IncludeSelf=*/true); RAI.isValid();
-         ++RAI)
-      if (isLiveIn(*RAI))
+    for (const MachineBasicBlock::RegisterMaskPair &LI : liveins())
+      if (TRI->regsOverlap(LI.PhysReg, Reg))
         return LQR_Live;
 
     return LQR_Dead;