/data/llvm-project/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp:2390:19: error: loop variable '[Reg, N]' creates a copy from type 'std::pair<unsigned int, llvm::SDValue> const' [-Werror,-Wrange-loop-construct]
  for (const auto [Reg, N] : RegsToPass) {
                  ^
/data/llvm-project/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp:2390:8: note: use reference type 'std::pair<unsigned int, llvm::SDValue> const &' to prevent copying
  for (const auto [Reg, N] : RegsToPass) {
       ^~~~~~~~~~~~~~~~~~~~~
                  &
/data/llvm-project/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp:2402:19: error: loop variable '[Reg, N]' creates a copy from type 'std::pair<unsigned int, llvm::SDValue> const' [-Werror,-Wrange-loop-construct]
  for (const auto [Reg, N] : RegsToPass)
                  ^
/data/llvm-project/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp:2402:8: note: use reference type 'std::pair<unsigned int, llvm::SDValue> const &' to prevent copying
  for (const auto [Reg, N] : RegsToPass)
       ^~~~~~~~~~~~~~~~~~~~~
                  &
2 errors generated.

This avoids using report_fatal_error and standardizes the error
message in a subset of the error conditions.

RuntimeLibcallInfo needs to be correct outside of codegen contexts.

This matches the underlying function in MachineMemOperand and how it is
printed when BaseAlign differs from Align.

Add a DAGCombine for FCOPYSIGN that removes the rounding which is never
needed as the sign bit is already in the correct place. This helps in particular the
rounding to f16 case which needs a libcall.

Also remove the roundings for other FP VTs and simplify the CPSDR
patterns correspondingly.

fp-copysign-03.ll test updated, now also covering the other FP VT
combinations.