IdeaWell

Project ideas from Hacker News discussions.

C Is Not a Low-Level Language (2018)

Original Article

Hacker News Discussion

📝 Discussion Summary (Click to expand)

Theme 1 – What “low‑level” really means is debated
Many commenters argue that the term is ambiguous: it can refer to proximity to the ISA, lack of runtime indirection, or the ability to control hardware directly.

  • “To me the definition of low‑level vs high‑level strictly comes from the indirection the language runtime provides for you. If the language compiles down to asm, it's low level.” – rfgplk
  • “I think that would be confusing. Intuitively ‘low level language’ describes the language. Your definition actually describes the nature of the compiler implementation.” – bee_rider
  • “Really a better title would be something like ‘a modern x86 processor is not a PDP‑11.’” – bee_rider

Theme 2 – C (and even assembly) hides modern CPU features
Several participants point out that contemporary CPUs rely on out‑of‑order execution, speculative execution, microcode, and deep pipelines, which are not exposed by C or standard assembly, making them poor “close‑to‑the‑metal” languages for today’s hardware.

  • “C does not expose modern CPU features like speculative execution… therefore C is not low‑level.” – applfanboysbgon (quoting the article)
  • “Even vp2intersectd … takes >1 cycle with 6 levels of pipelining… if literally not even a chip's ISA is 'low level' then the term is effectively meaningless.” – weitendorf
  • “Assembly expose instructions that C was never meant to work with… LLMV intermediate representation is probably more low level (closer to the real compute model it runs on).” – aDyslecticCrow

Theme 3 – Alternatives exist for truly low‑level control
Commenters suggest ways to get nearer to the hardware: using intrinsics/assembly blocks, GPU kernels (CUDA, shaders), languages with explicit SIMD or LLVM IR access, or hardware‑description languages for FPGAs.

  • “Better control over the async nature of the hardware is part of what makes GPU kernels efficient… I think most languages lack good (i.e. non‑intrinsic‑based) support for wide registers or anything SIMD related.” – legobmw99
  • “Probably Mojo, it doesnt just talk to your CPU it also will talk to your GPU bypassing the need for CUDA.” – giancarlostoro
  • “You can take python and write an LLVM frontend for it and it would instantly become a low‑level language.” – rfgplk
  • “Verilog is very much NOT a low level language… it’s a hardware description language.” – stephen_cagle (showing the contrast)
  • “If you can quickly and easily drop into machine‑level instructions to provide explicit implementation semantics… that sure seems ‘low level’ to me.” – weitendorf (referring to intrinsics)

🚀 Project Ideas

Generating project ideas…

MicroSpec DSL

Summary

  • A domain‑specific language that lets programmers express explicit microarchitectural controls (speculative execution barriers, prefetch hints, SIMD width, cache‑level directives) and compiles to LLVM IR with the appropriate intrinsics.
  • Core value proposition: gives developers a “true low‑level” way to target modern superscalar CPUs without wrestling with compiler‑specific intrinsics or inline assembly.

Details

Key Value
Target Audience Systems programmers, performance engineers, compiler researchers
Core Feature Language constructs for out‑of‑order execution fences, hardware prefetch, cache‑level hints, and SIMD width selection
Tech Stack Rust (parser + codegen), LLVM‑C API, optional WebAssembly playground
Difficulty Medium
Monetization Hobby

Notes

  • HN users lamented that “C doesn't expose modern CPU features like speculative execution” and wished for a language that “expose[s] the async nature of the hardware” (legobmw99, Mustache_kimono). MicroSpec directly answers that request.
  • Provides a concrete target for discussion about what a low‑level language for out‑of‑order CPUs should look like, potentially sparking new compiler extensions or ISA proposals.

PipelineProfiler

Summary

  • An interactive web‑based tool that visualizes pipeline stalls, branch mispredictions, cache hits/misses, and execution unit utilization in real time, tied back to source lines via hardware performance counters (perf/eBPF).
  • Core value proposition: lets developers see exactly where the CPU deviates from the simple PDP‑11 model and experiment with code or compiler flags to regain control.

Details

Key Value
Target Audience Performance‑focused developers, students, researchers, console/game engine teams
Core Feature Live microarchitectural heatmap (pipeline, cache, branch) overlaid on source code; ability to inject annotations (e.g., prefetch) and see impact
Tech Stack Electron/React frontend, Rust backend using perf/eBPF, perfetto for tracing, WebGPU for GPU‑accelerated graphs
Difficulty High
Monetization Hobby

Notes

  • Commenters noted that “the ISA no longer maintains 1:1 instruction‑level implementation” and wanted ways to “control precisely which kernels stay in which cache levels” (veqq, legobmw99). PipelineProfiler makes those hidden effects visible.
  • Enables practical experimentation: users can try inserting prefetch or lfence and instantly measure the effect, feeding back into language or compiler design discussions.

SIMDx Portable Width Control

Summary

  • A header‑only C++ library (with Rust crate equivalent) that provides generic SIMD vectors where the bit‑width (128, 256, 512, 1024) is a template parameter; the library maps to the best available intrinsics (SSE, AVX, AVX‑512, SVE, NEON) or falls back to loop‑based code.
  • Core value proposition: write SIMD code once, explicitly choose the width you want to target, and get portable, high‑performance execution without intrinsics hell.

Details

Key Value
Target Audience Game developers, HPC engineers, ML library authors, anyone needing data‑parallel kernels
Core Feature Width‑parameterized SIMD types with aligned load/store, prefetch, and reduction ops; automatic ISA dispatch
Tech Stack C++20 (concepts, consteval), Rust optional bindings, CMake, CI with GCC/Clang/MSVC
Difficulty Medium
Monetization Hobby

Notes

  • Many HN participants complained that “most languages lack good … support for wide registers or anything SIMD related” (legobmw99). SIMDx gives that support in a portable, explicit‑control fashion.
  • By exposing the width as a compile‑time choice, it lets programmers reason about the hardware’s parallel capabilities—addressing the desire for “better control over the async nature of the hardware” while staying usable across CPUs.

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