[llvm-commits] [llvm] r47395 - /llvm/trunk/lib/CodeGen/LiveVariables.cpp

[Bill Wendling]

Author: void
Date: Wed Feb 20 13:35:34 2008
New Revision: 47395

URL: http://llvm.org/viewvc/llvm-project?rev=47395&view=rev
Log:
Improve some comments explaining the "handle kills" stuff better.

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

Modified: llvm/trunk/lib/CodeGen/LiveVariables.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveVariables.cpp?rev=47395&r1=47394&r2=47395&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/LiveVariables.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveVariables.cpp Wed Feb 20 13:35:34 2008
@@ -296,6 +296,7 @@
 ///     last def/use of the register, or
 ///   - The register has sub-registers and none of them are killed elsewhere.
 ///
+/// SubKills is filled with the set of sub-registers that are killed elsewhere.
 bool LiveVariables::HandlePhysRegKill(unsigned Reg, const MachineInstr *RefMI,
                                       SmallSet<unsigned, 4> &SubKills) {
   const unsigned *SubRegs = RegInfo->getImmediateSubRegisters(Reg);
@@ -320,8 +321,9 @@
   return false;
 }
 
-/// HandlePhysRegKill - Calls the recursive version of HandlePhysRegKill. (See
-/// above for details.)
+/// HandlePhysRegKill - Returns true if the whole register is killed in the
+/// machine instruction. If only some of its sub-registers are killed in this
+/// machine instruction, then mark those as killed and return false.
 bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *RefMI) {
   SmallSet<unsigned, 4> SubKills;