Now we have default abi lp64 for rv64if and ilp32 for rv32if, which is
different with riscv-gnu-toolchain. In
8e9fb09a0c/configure (L3385)
when have f and not d, it prefers lp64f/ilp32f but no soft float. This
patch tries to make their behaviors consistent.
We don't have very many compressible FP instructions, just load and store.
These instruction require the FP register to be f8-f15.
This patch changes the FP allocation order to prioritize f10-f15 first.
These are also the FP argument registers. So I allocated them in reverse
order starting at f15 to avoid taking the first argument registers.
This appears to match gcc allocation order.
Reviewed By: asb
Differential Revision: https://reviews.llvm.org/D146488
Lowering certain float vectors without legal vector types could cause a
crash due to a bad interaction between passing floats via GPRs and
argument splitting. Split vector floats appear just like scalar floats.
Under certain situations we choose to pass these float arguments via
GPRs and use an XLenVT location and set the 'BCvt' info to track how
they must be converted back to floating-point values. However, later
logic for handling split arguments may take over, in which case we lose
the previous information and set the 'Indirect' info, thus incorrectly
lowering to integer types.
I don't believe that we would have come across the notion of split
floating-point arguments before. This patch addresses the issue by
updating the lowering so that split arguments are only passed indirectly
when they are scalar integer types.
This has some change to how we lower some larger illegal float vectors,
as can be seen in 'fastcc-float.ll' where the vector is now passed
partly in registers and partly on the stack.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D102852
