From ee7627ee409b1f2a3ebbf6c868adbc0d75a1f43b Mon Sep 17 00:00:00 2001 From: Tsukasa OI Date: Tue, 19 Aug 2025 01:37:35 +0000 Subject: [PATCH] std_detect: RISC-V: implement implication to "C" Just like we implemented relatively complex rules to imply other extensions **from** "C" (and some others), this commit implements implication **to** the "C" extension from others, complying the following text in the ISA Manual (although there's no direct imply/depend references). > The C extension is the superset of the following extensions: > > - Zca > - Zcf if F is specified (RV32 only) > - Zcd if D is specified This is formally verified so that no other extension combinations (*not* in this implementation) can (currently) imply the "C" extension. --- library/std_detect/src/detect/os/riscv.rs | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/library/std_detect/src/detect/os/riscv.rs b/library/std_detect/src/detect/os/riscv.rs index c6acbd3525bd3..9b9e0cba09d1c 100644 --- a/library/std_detect/src/detect/os/riscv.rs +++ b/library/std_detect/src/detect/os/riscv.rs @@ -119,11 +119,31 @@ pub(crate) fn imply_features(mut value: cache::Initializer) -> cache::Initialize imply!(d | zfhmin | zfa => f); imply!(zfbfmin => f); // and some of (not all) "Zfh" instructions. - // Relatively complex implication rules from the "C" extension. + // Relatively complex implication rules around the "C" extension. + // (from "C" and some others) imply!(c => zca); imply!(c & d => zcd); #[cfg(target_arch = "riscv32")] imply!(c & f => zcf); + // (to "C"; defined as superset) + cfg_select! { + target_arch = "riscv32" => { + if value.test(Feature::d as u32) { + imply!(zcf & zcd => c); + } else if value.test(Feature::f as u32) { + imply!(zcf => c); + } else { + imply!(zca => c); + } + } + _ => { + if value.test(Feature::d as u32) { + imply!(zcd => c); + } else { + imply!(zca => c); + } + } + } imply!(zicntr | zihpm | f | zfinx | zve32x => zicsr);