Displaying 1 result from an estimated 1 matches for "isphyregwritten".
2013 Jan 27
1
[LLVMdev] Clarification about callee saved regs and MachineRegisterInfo::isPhyRegUsed
...true if the register is read or written in the function.
If
this is right, why do we save a register if it is only read in the
function ?? I would have expected that calculateCalleeSavedRegisters use
another function which would return true only when the register is
written, something like "isPhyRegWritten".
You may ask why a function
would only read a callee saved register ?? The case I have in mind is
the link register, like LR in ARM: a typical return instruction is BX
LR. BX instruction only reads LR, no need to push/pop LR just because a
function ends by BX LR...
The ARM backend don'...