This fixes a problem originally reported at
https://github.com/riscv/riscv-binutils-gdb/issues/173
If you have code linked at address zero, you can have a lui instruction
loading a value 0x800 which gets relaxed to a c.lui which is valid (c.lui 0x1
followed by addi -0x800). Relaxation can reduce the value below 0x800 at which
point the c.lui 0x0 is no longer valid. We can fix this by converting the
c.lui to a c.li which can load 0.
bfd/
* elfnn-riscv.c (perform_relocation) <R_RISCV_RVC_LUI>: If
RISCV_CONST_HIGH_PART (value) is zero, then convert c.lui instruction
to c.li instruction, and use ENCODE_RVC_IMM to set value.
ld/
* testsuite/ld-riscv-elf/c-lui-2.d: New.
* testsuite/ld-riscv-elf/c-lui-2.ld: New.
* testsuite/ld-riscv-elf/c-lui-2.s: New.
* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Run the c-lui-2 test.
