Clarify and doxygen-ify comments

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185030 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 8 deletions

diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index 0e1e50e..6a9bfc3 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -72,17 +72,21 @@ ARMBaseRegisterInfo::getCallPreservedMask(CallingConv::ID) const {
 }
 
 const uint32_t*
-ARMBaseRegisterInfo::getThisReturnPreservedMask(CallingConv::ID) const {
-  return (STI.isTargetIOS() && !STI.isAAPCS_ABI())
-    ? CSR_iOS_ThisReturn_RegMask : CSR_AAPCS_ThisReturn_RegMask;
-  // This should return NULL in the case of any calling convention that does
-  // not use the same register for an i32 first argument and an i32 return
-  // value
+ARMBaseRegisterInfo::getNoPreservedMask() const {
+  return CSR_NoRegs_RegMask;
 }
 
 const uint32_t*
-ARMBaseRegisterInfo::getNoPreservedMask() const {
-  return CSR_NoRegs_RegMask;
+ARMBaseRegisterInfo::getThisReturnPreservedMask(CallingConv::ID) const {
+  // This should return a register mask that is the same as that returned by
+  // getCallPreservedMask but that additionally preserves the register used for
+  // the first i32 argument (which must also be the register used to return a
+  // single i32 return value)
+  //
+  // In case that the calling convention does not use the same register for
+  // both, the function should return NULL (does not currently apply)
+  return (STI.isTargetIOS() && !STI.isAAPCS_ABI())
+    ? CSR_iOS_ThisReturn_RegMask : CSR_AAPCS_ThisReturn_RegMask;
 }
 
 BitVector ARMBaseRegisterInfo::