[experiment] remove the portable simd f16 patch

[folkertdev]

I believe this will fail but let's see what happens.

[folkertdev]

As expected

https://triage.rust-lang.org/gha-logs/rust-lang/rustc_codegen_cranelift/86638749132?pr=1675

  = note: C:/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: D:\a\rustc_codegen_cranelift\rustc_codegen_cranelift\build\portable-simd_target\x86_64-pc-windows-gnu\debug\deps\libproptest-f4ca5451e39982af.rlib(proptest-f4ca5451e39982af.proptest.26d0c0f6a929e698-cgu.05.rcgu.o):proptest.26d0c0f6a929e698-cgu.05.o:(.rdata$.refptr+0x0): undefined reference to `floorf16'
          C:/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: D:\a\rustc_codegen_cranelift\rustc_codegen_cranelift\build\portable-simd_target\x86_64-pc-windows-gnu\debug\deps\libproptest-f4ca5451e39982af.rlib(proptest-f4ca5451e39982af.proptest.26d0c0f6a929e698-cgu.05.rcgu.o):proptest.26d0c0f6a929e698-cgu.05.o:(.rdata$.refptr+0x0): undefined reference to `ceilf16'
          collect2.exe: error: ld returned 1 exit status

So that means we additionally need fallbacks for floorf16 and ceilf16. I'll look into that, seems straightforward.

[folkertdev]

This is still missing the return false, // has a fallback via f32s that #1674 adds for some of the other functions

[folkertdev]

Hmm, the changes here are good, but I think we need the the additional gates I added. those are merged into portable_simd but not yet synced.

[folkertdev]

I think this needs one more sync, rust-lang/rust#159582 should be in today's nightly.

[bjorn3]

I've done a sync again.

[folkertdev]

Hmm, this fails on non-windows now because it tries to perform f16 SIMD operations. For f32 and f64 this performs libcalls

            simd_for_each_lane(fx, a, ret, &|fx, lane_ty, _ret_lane_ty, lane| {
                let lane_ty = match lane_ty.kind() {
                    ty::Float(FloatTy::F32) => types::F32,
                    ty::Float(FloatTy::F64) => types::F64,
                    _ => unreachable!("{:?}", lane_ty),
                };
                let name = match (intrinsic, lane_ty) {
                    (sym::simd_fsin, types::F32) => "sinf",
                    (sym::simd_fsin, types::F64) => "sin",
                    (sym::simd_fcos, types::F32) => "cosf",
                    (sym::simd_fcos, types::F64) => "cos",
                    (sym::simd_fexp, types::F32) => "expf",
                    (sym::simd_fexp, types::F64) => "exp",
                    (sym::simd_fexp2, types::F32) => "exp2f",
                    (sym::simd_fexp2, types::F64) => "exp2",
                    (sym::simd_flog, types::F32) => "logf",
                    (sym::simd_flog, types::F64) => "log",
                    (sym::simd_flog10, types::F32) => "log10f",
                    (sym::simd_flog10, types::F64) => "log10",
                    (sym::simd_flog2, types::F32) => "log2f",
                    (sym::simd_flog2, types::F64) => "log2",
                    (sym::simd_round, types::F32) => "roundf",
                    (sym::simd_round, types::F64) => "round",
                    (sym::simd_round_ties_even, types::F32) => "rintf",
                    (sym::simd_round_ties_even, types::F64) => "rint",
                    _ => unreachable!("{:?}", intrinsic),
                };
                fx.lib_call(
                    name,
                    vec![AbiParam::new(lane_ty)],
                    vec![AbiParam::new(lane_ty)],
                    &[lane],
                )[0]
            });

But for f16 we want to instead call the fallback body. In fact, perhaps we always want to call the fallback body now, given that it exists. Is there any way to do that from within this code?