The previous implementation translated from names like sifive-7-series
to sifive-7-rv32 or sifive-7-rv64. This also required sifive-7-rv32
and sifive-7-rv64 to be valid CPU names. As those are not real
CPUs it doesn't make sense to accept them in -mcpu.
This patch does away with the translation and adds sifive-7-series
directly to RISCV.td. Removing sifive-7-rv32 and sifive-7-rv64.
sifive-7-series is only allowed in -mtune.
I've also added "rocket" to RISCV.td but have not removed rocket-rv32
or rocket-rv64.
To prevent -mcpu=sifive-7-series or -mcpu=rocket being used with llc,
I've added a Feature32Bit to all rv32 CPUs. And made it an error to
have an rv32 triple without Feature32Bit. sifive-7-series and rocket
do not have Feature32Bit or Feature64Bit set so the user would need
to provide -mattr=+32bit or -mattr=+64bit along with the -mcpu to
avoid the error.
SiFive no longer names their newer products with 3, 5, or 7 series.
Instead we have p200 series, x200 series, p500 series, and p600 series.
Following the previous behavior would require a sifive-p500-rv32 and
sifive-p500-rv64 in order to support -mtune=sifive-p500-series. There
is currently no p500 product, but it could start getting confusing if
there was in the future.
I'm open to hearing alternatives for how to achieve my main goal
of removing sifive-7-rv32/rv64 as a CPU name.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D131708
- The goal of this patch is improve option compatible with RISCV-V GCC,
-mcpu support on GCC side will sent patch in next few days.
- -mtune only affect the pipeline model and non-arch/extension related
target feature, e.g. instruction fusion; in td file it called
TuneFeatures, which is introduced by X86 back-end[1].
- -mtune accept all valid option for -mcpu and extra alias processor
option, e.g. `generic`, `rocket` and `sifive-7-series`, the purpose is
option compatible with RISCV-V GCC.
- Processor alias for -mtune will resolve according the current target arch,
rv32 or rv64, e.g. `rocket` will resolve to `rocket-rv32` or `rocket-rv64`.
- Interaction between -mcpu and -mtune:
* -mtune has higher priority than -mcpu for pipeline model and
TuneFeatures.
[1] https://reviews.llvm.org/D85165
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D89025
Summary:
1. gcc uses `-march` and `-mtune` flag to chose arch and
pipeline model, but clang does not have `-mtune` flag,
we uses `-mcpu` to chose both infos.
2. Add SiFive e31 and u54 cpu which have default march
and pipeline model.
3. Specific `-mcpu` with rocket-rv[32|64] would select
pipeline model only, and use the driver's arch choosing
logic to get default arch.
Reviewers: lenary, asb, evandro, HsiangKai
Reviewed By: lenary, asb, evandro
Tags: #llvm, #clang
Differential Revision: https://reviews.llvm.org/D71124
Craig Topper