I'm confused about the RISC-V ABI Register Names. For example, Table 18.2 in the "RISC-V Instruction Set Manual, Volume I: User-Level ISA, Version 2.0" at page 85 specifies that the stack pointer
sp is register
x14. However, the instruction
is compiled to 0x00000113 by riscv64-unknown-elf-as (
-m32 does not make a difference). In binary:
000000000000 00000 000 00010 0010011 ^imm ^rs1 ^f3 ^rd ^opcode
sp seems to be
x2. Then I googled a bit and found the RISC-V Linux User's Manual. This document states that
So what is it? Are there different ABIs? Can I set the ABI with a command line option to
riscv64-unknown-elf-*? Is there a comprehensive table somewhere?
The stack pointer is now
The ABI was modified to better accommodate the new RISC-V compressed spec, which puts the 8 most-used registers next to each other in x8-x15.
Note: do not trust ANY non riscv.org webpage. Quan Nguyen makes this clear in his introduction that the "RISC-V Linux User's Manual" is for documenting the porting process and that accuracy is NOT guaranteed.
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