[PATCH] D10914: Allow BranchFolding to operate on instructions with virtual registers

[Dan Gohman]

sunfish created this revision.
sunfish added a subscriber: llvm-commits-list.

By observing that virtual registers don't have aliases or subregisters in the way physical registers do, BranchFolding can work on instructions with virtual registers too.

http://reviews.llvm.org/D10914

Files:
  lib/CodeGen/BranchFolding.cpp

Index: lib/CodeGen/BranchFolding.cpp
===================================================================
--- lib/CodeGen/BranchFolding.cpp
+++ lib/CodeGen/BranchFolding.cpp
@@ -1598,8 +1598,11 @@
     if (!Reg)
       continue;
     if (MO.isUse()) {
-      for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
-        Uses.insert(*AI);
+      if (TargetRegisterInfo::isVirtualRegister(Reg))
+        Uses.insert(Reg);
+      else
+        for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+          Uses.insert(*AI);
     } else {
       if (!MO.isDead())
         // Don't try to hoist code in the rare case the terminator defines a
@@ -1608,8 +1611,11 @@
 
       // If the terminator defines a register, make sure we don't hoist
       // the instruction whose def might be clobbered by the terminator.
-      for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
-        Defs.insert(*AI);
+      if (TargetRegisterInfo::isVirtualRegister(Reg))
+        Defs.insert(Reg);
+      else
+        for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+          Defs.insert(*AI);
     }
   }
 
@@ -1669,11 +1675,17 @@
         Uses.insert(*AI);
     } else {
       if (Uses.erase(Reg)) {
-        for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
-          Uses.erase(*SubRegs); // Use sub-registers to be conservative
+        if (TargetRegisterInfo::isVirtualRegister(Reg))
+          Uses.erase(Reg);
+        else
+          for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs)
+            Uses.erase(*SubRegs); // Use sub-registers to be conservative
       }
-      for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
-        Defs.insert(*AI);
+      if (TargetRegisterInfo::isVirtualRegister(Reg))
+        Defs.insert(Reg);
+      else
+        for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+          Defs.insert(*AI);
     }
   }
 


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