Remove dependence of C softfloat code on Sail model. #340
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The flags and result for a softfloat operation are currently pushed to the Sail code from C like this:
// C
zfloat_result = res.v;
zfloat_fflags = (mach_bits)softfloat_exceptionFlags
// Sail
register float_result : bits(64)
register float_fflags : bits(64)
This changes it to pull the flags from the Sail side with a callback:
// C
mach_bits softfloat_float_flags(unit u)
{
return (mach_bits)softfloat_exceptionFlags;
}
// Sail
val extern_float_flags = {c: "softfloat_float_flags", ocaml: "Softfloat.float_flags", lem: "softfloat_float_flags"} : (unit) -> bits_LU
The `float_result` is changed to just be the return value of all of the functions.
The benefits are:
1. It uses the official FFI system instead of hackily reaching into the generated C code.
2. It removes the two-way dependence between the C softfloat code and the Sail model. The C softfloat code no longer has any references to the Sail model.
Tested with `run_fp_tests.sh` - all 82 tests pass.
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The flags and result for a softfloat operation are currently pushed to the Sail code from C like this:
This changes it to pull the flags from the Sail side with a callback:
The
float_resultis changed to just be the return value of all of the functions.The benefits are:
Tested with
run_fp_tests.sh- all 82 tests pass.