From b4e090dffc4bed40cee22b94560aa8dd3b4af013 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Wed, 29 Aug 2012 23:52:55 +0000 Subject: [PATCH] Add a bit of documentation to copyPhysReg. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162879 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Target/TargetInstrInfo.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/include/llvm/Target/TargetInstrInfo.h b/include/llvm/Target/TargetInstrInfo.h index 44953a287ad..d7cc1cf45a6 100644 --- a/include/llvm/Target/TargetInstrInfo.h +++ b/include/llvm/Target/TargetInstrInfo.h @@ -459,6 +459,13 @@ public: } /// copyPhysReg - Emit instructions to copy a pair of physical registers. + /// + /// This function should support copies within any legal register class as + /// well as any cross-class copies created during instruction selection. + /// + /// The source and destination registers may overlap, which may require a + /// careful implementation when multiple copy instructions are required for + /// large registers. See for example the ARM target. virtual void copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, DebugLoc DL, unsigned DestReg, unsigned SrcReg, -- 2.34.1