diff options
| -rw-r--r-- | include/llvm/CodeGen/MachineRegisterInfo.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/llvm/CodeGen/MachineRegisterInfo.h b/include/llvm/CodeGen/MachineRegisterInfo.h index 3866b2650d..bd674d2b96 100644 --- a/include/llvm/CodeGen/MachineRegisterInfo.h +++ b/include/llvm/CodeGen/MachineRegisterInfo.h @@ -171,6 +171,14 @@ public: /// replaceRegWith - Replace all instances of FromReg with ToReg in the /// machine function. This is like llvm-level X->replaceAllUsesWith(Y), /// except that it also changes any definitions of the register as well. + /// + /// Note that it is usually necessary to first constrain ToReg's register + /// class to match the FromReg constraints using: + /// + /// constrainRegClass(ToReg, getRegClass(FromReg)) + /// + /// That function will return NULL if the virtual registers have incompatible + /// constraints. void replaceRegWith(unsigned FromReg, unsigned ToReg); /// getRegUseDefListHead - Return the head pointer for the register use/def |