diff options
| author | Andrew Waterman <andrew@sifive.com> | 2018-12-20 01:00:04 -0800 |
|---|---|---|
| committer | Andrew Waterman <andrew@sifive.com> | 2018-12-20 01:00:04 -0800 |
| commit | e47bcb818e312aa04d99b6cd3781539a45db965e (patch) | |
| tree | 4aafe0846efc59b097a7a66c7183d63d51f1b07b | |
| parent | 87e4ae880bb3169a1128ad9fa2bcdac91a1219e4 (diff) | |
| download | riscv-isa-manual-e47bcb818e312aa04d99b6cd3781539a45db965e.zip riscv-isa-manual-e47bcb818e312aa04d99b6cd3781539a45db965e.tar.gz riscv-isa-manual-e47bcb818e312aa04d99b6cd3781539a45db965e.tar.bz2 | |
ABIs could dedicate other JALR base registers
Closes #309
| -rw-r--r-- | src/rv32.tex | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/rv32.tex b/src/rv32.tex index a29fc66..ee8ed4f 100644 --- a/src/rv32.tex +++ b/src/rv32.tex @@ -769,7 +769,9 @@ address will usually quickly raise an exception. When used with a base {\em rs1}$=${\tt x0}, JALR can be used to implement a single instruction subroutine call to the lowest \wunits{2}{KiB} or highest \wunits{2}{KiB} address region from anywhere in the address space, which could -be used to implement fast calls to a small runtime library. +be used to implement fast calls to a small runtime library. Alternatively, +an ABI could dedicate a general-purpose register to point to a library +elsewhere in the address space. \end{commentary} The JAL and JALR instructions will generate an |