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When a function call occurs, caller-saved registers are typically invalidated since the callee may clobber them. However, DWARF debug info provides location ranges that indicate exactly where a variable is valid in a register. Track the DWARF location range end address in type_state_reg and use it to determine if a caller-saved register should be preserved across a call. If the current call address is within the DWARF-specified lifetime of the variable, keep the register state valid instead of invalidating it. This improves type annotation for code where the compiler knows a register value survives across calls (e.g., when the callee is known not to clobber certain registers or when the value is reloaded after the call at the same logical location). Changes: - Add `end` and `has_range` fields to die_var_type to capture DWARF location range information - Add `lifetime_active` and `lifetime_end` fields to type_state_reg - Check location lifetime before invalidating caller-saved registers Signed-off-by: Zecheng Li <zli94@ncsu.edu> Signed-off-by: Namhyung Kim <namhyung@kernel.org>