ARM64: Detect some arm features and let LLVM know if they are or aren't present via attributes

- On x86, LLVM has robust detection for the CPU name. If a CPU like skylake has AVX disabled, it will fall back to something without AVX (nehalem)
- On ARM, detection is not as robust. For instance, on my snapdragon 8 gen 2, it assumes that we have SVE support, as the cortex-x3 supports SVE.
- If an ARM cpu is paired with other cpus from another generation which doesn't support the same instructions as the cortex-x3, or if the cortex-x3 just has SVE disabled for no apparant reason (in the case of the snapdragon 8 gen 2)
- We need to actually detect that ourselves.
- Beyond SVE also detect support for some instructions that might be useful SPU LLVM when optimized with intrinsics.
This commit is contained in:
Malcolm
2026-02-01 03:00:09 +00:00
committed by Elad
parent 8f066541a3
commit b2469039af
3 changed files with 148 additions and 1 deletions
+25
View File
@@ -688,6 +688,30 @@ jit_compiler::jit_compiler(const std::unordered_map<std::string, u64>& _link, co
mem = std::make_unique<MemoryManager1>(std::move(symbols_cement));
}
std::vector<std::string> attributes;
#if defined(ARCH_ARM64)
if (utils::has_sha3())
attributes.push_back("+sha3");
else
attributes.push_back("-sha3");
if (utils::has_dotprod())
attributes.push_back("+dotprod");
else
attributes.push_back("-dotprod");
if (utils::has_sve())
attributes.push_back("+sve");
else
attributes.push_back("-sve");
if (utils::has_sve2())
attributes.push_back("+sve2");
else
attributes.push_back("-sve2");
#endif
{
m_engine.reset(llvm::EngineBuilder(std::move(null_mod))
.setErrorStr(&result)
@@ -699,6 +723,7 @@ jit_compiler::jit_compiler(const std::unordered_map<std::string, u64>& _link, co
//.setCodeModel(llvm::CodeModel::Large)
#endif
.setRelocationModel(llvm::Reloc::Model::PIC_)
.setMAttrs(attributes)
.setMCPU(m_cpu)
.create());
}