[llvm-dev] [RISCV] Does "V" Extention come with "F" "D" "Zfh" Extentions?

Kai Wang via llvm-dev llvm-dev at lists.llvm.org
Mon Mar 29 06:32:07 PDT 2021


Hi,

There is no such implication between V and F/D/Zfh. If you want to use the
vector unit to process float/double/fp16 data, you need to specify F, D and
Zfh accordingly.

Kai

On Mon, Mar 29, 2021 at 5:58 PM DriveLife via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi all,
> When I tried to run "opt -loop-vectorize" on a testcase, an "UNREACHABLE
> executed" error was received.
> The full command is "./build/bin/opt -loop-vectorize -dce -instcombine
> -mtriple riscv64-linux-gnu -mattr=+experimental-v
> -debug-only=loop-vectorize -S
> llvm/test/Transforms/LoopVectorize/RISCV/basic-vec.ll"(basic-vec.ll as
> attachment).
> Missing "+f" in "-mattr" is the reason of "UNREACHABLE executed" error.
> The command "./build/bin/opt -loop-vectorize -dce -instcombine -mtriple
> riscv64-linux-gnu -mattr=+experimental-v,+f -debug-only=loop-vectorize -S
> llvm/test/Transforms/LoopVectorize/RISCV/basic-vec.ll" works well.
> So can we assume that if a target has StdExtF, it also has StdExtF,
> StdExtD and StdExtZfh?
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