From cf2d1aa485e1164e28eb1aa2e258659f69b6b173 Mon Sep 17 00:00:00 2001 From: Bill Wendling Date: Wed, 20 Feb 2008 19:35:34 +0000 Subject: Improve some comments explaining the "handle kills" stuff better. llvm-svn: 47395 --- llvm/lib/CodeGen/LiveVariables.cpp | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'llvm/lib/CodeGen/LiveVariables.cpp') diff --git a/llvm/lib/CodeGen/LiveVariables.cpp b/llvm/lib/CodeGen/LiveVariables.cpp index ea27b2e08e0..809048e8ef7 100644 --- a/llvm/lib/CodeGen/LiveVariables.cpp +++ b/llvm/lib/CodeGen/LiveVariables.cpp @@ -296,6 +296,7 @@ void LiveVariables::addRegisterKills(unsigned Reg, MachineInstr *MI, /// 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 &SubKills) { const unsigned *SubRegs = RegInfo->getImmediateSubRegisters(Reg); @@ -320,8 +321,9 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, const MachineInstr *RefMI, 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 SubKills; -- cgit v1.2.3