emscripten build

[jedbrown]

I can build and run the pure libceed examples, which means we could embed them in a static web page that would run simulations in the user's browser.

This now builds cleanly:

$ emmake make STATIC=1 OPT=-O build/ex2-surface.wasm
[...]
$ wasmer run build/ex2-surface.wasm -- -s 32767
[...]
Exact mesh surface area    :  6
Computed mesh surface area :  5.9548265118955
Surface area error         : -0.04517348810445

Increasing the size causes calloc to fail, likely to do some default memory limits that I haven't worked out yet.

Emscripten docs: https://emscripten.org/docs/compiling/Building-Projects.html#building-projects

[jeremylt]

Do we want to include this in the release? The above suggestion would be a ~15 minute commit that I could put together.

[jedbrown]

I think it would be wonderful if we can, and then add a cursory emscripten build (just the base library) to CI.

[jedbrown]

I don't think it was intended to close this PR, though this PR should be rebased (by someone, maybe me).

[jeremylt]

I can do a quick rebase

[jeremylt]

$ emmake make STATIC=1 OPT=-O build/ex2-surface.wasm -j
make: make STATIC=1 OPT=-O build/ex2-surface.wasm -j
make: 'lib' with optional backends: 
          CC build/interface/ceed-basis.o
          CC build/interface/ceed.o
          CC build/interface/ceed-elemrestriction.o
          CC build/interface/ceed-fortran.o
          CC build/interface/ceed-jit-source-root-default.o
          CC build/interface/ceed-jit-tools.o
          CC build/interface/ceed-operator.o
          CC build/interface/ceed-preconditioning.o
          CC build/interface/ceed-qfunction.o
          CC build/interface/ceed-qfunctioncontext.o
          CC build/interface/ceed-qfunction-register.o
          CC build/interface/ceed-register.o
          CC build/interface/ceed-tensor.o
          CC build/interface/ceed-types.o
          CC build/interface/ceed-vector.o
          CC build/gallery/identity/ceed-identity.o
          CC build/gallery/mass/ceed-mass1dbuild.o
          CC build/gallery/mass/ceed-mass2dbuild.o
          CC build/gallery/mass/ceed-mass3dbuild.o
          CC build/gallery/mass/ceed-massapply.o
          CC build/gallery/mass-vector/ceed-vectormassapply.o
          CC build/gallery/poisson/ceed-poisson1dapply.o
          CC build/gallery/poisson/ceed-poisson1dbuild.o
          CC build/gallery/poisson/ceed-poisson2dapply.o
          CC build/gallery/poisson/ceed-poisson2dbuild.o
          CC build/gallery/poisson/ceed-poisson3dapply.o
          CC build/gallery/poisson/ceed-poisson3dbuild.o
          CC build/gallery/poisson-vector/ceed-vectorpoisson1dapply.o
          CC build/gallery/poisson-vector/ceed-vectorpoisson2dapply.o
          CC build/gallery/poisson-vector/ceed-vectorpoisson3dapply.o
          CC build/gallery/scale/ceed-scale.o
          CC build/backends/ref/ceed-ref-basis.o
          CC build/backends/ref/ceed-ref-operator.o
          CC build/backends/ref/ceed-ref-qfunction.o
          CC build/backends/ref/ceed-ref-qfunctioncontext.o
          CC build/backends/ref/ceed-ref-restriction.o
          CC build/backends/ref/ceed-ref-tensor.o
          CC build/backends/ref/ceed-ref-vector.o
          CC build/backends/ref/ceed-ref.o
          CC build/backends/blocked/ceed-blocked-operator.o
          CC build/backends/blocked/ceed-blocked.o
          CC build/backends/opt/ceed-opt-blocked.o
          CC build/backends/opt/ceed-opt-operator.o
          CC build/backends/opt/ceed-opt-serial.o
          CC build/backends/opt/ceed-opt-tensor.o
          CC build/backends/ceed-backend-weak.o
          CC build/gallery/ceed-gallery-weak.o
          AR lib/libceed.a
      LINK.c build/ex2-surface.wasm

$ wasmer run build/ex2-surface.wasm -- -s 32767
Selected options: [command line option] : <current value>
  Ceed specification [-c] : /cpu/self
  Mesh dimension     [-d] : 3
  Mesh degree        [-m] : 4
  Solution degree    [-p] : 4
  Num. 1D quadr. pts [-q] : 6
  Approx. # unknowns [-s] : 32767
  QFunction source   [-g] : header

Mesh size: nx = 8, ny = 8, nz = 4
Number of mesh nodes     : 18513
Number of solution nodes : 18513
 done.
Exact mesh surface area    :  6
Computed mesh surface area :  5.9548265118955
Surface area error         : -0.04517348810445

[jeremylt]

Did you want to add this to the docs here or in a follow-up?

[jedbrown]

Thanks. I think this can be a sleeper feature until we figure out the size limit and get it in CI, at which point we can announce it.