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2e66995c01
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Fix the I/O routines for floats so that can roundtrip.
library/string.m:
Ensure that string__float_to_string returns a float that is
round-trippable. On the C backend we do that by starting at the min
precision required and increasing it until the float roundtrips.
This functionality is provided by ML_sprintf_float, so that it can
be reused in io.m. On the IL backend the R flag guarantees that a
double will be round-trippable, so we just use that.
Change string__to_float so that it uses the format string for the
precision float that we are using, and export this predicate for use
by the trace system.
Delete the unused string__float_to_f_string.
library/io.m:
Print round-tripable floats in io__write_float.
For the C backend use ML_sprintf_float to avoid unnecessary string
allocation. For other backends use string__float_to_string to
generate a valid float.
trace/mercury_trace_util.c:
Rather than duplicating the code from the library, call the code in
the library.
tests/general/Mmakefile:
tests/general/float_roundtrip.exp:
tests/general/float_roundtrip.m:
Test that floats roundtrip for different required miniumum
precisions.
This directory holds the trace subsystem, i.e. the part of the Mercury debugger that is written in C code. Notes on interfacing with other subsystems ------------------------------------------ If tracing is enabled, the compiler includes calls to MR_trace() in the generated C code. The trace subsystem in this directory is therefore called directly from Mercury code, via MR_trace() in runtime/mercury_trace_base.c. One of the first things it does is to save the original values of the Mercury registers in a variable called `saved_regs'. The reason it needs to do this is that the code here may modify registers, e.g. by allocating memory using incr_hp or by calling Mercury code. Once the original values of the registers have been saved, the trace subsystem is free to modify the Mercury registers. So for all code in this directory, the usual convention is that the original values of the Mercury registers are in `saved_regs', while the current (scratch) values for the normal non-transient Mercury registers etc. are in their normal locations, not in the fake_reg copies, and the transient (register window) registers, if any, are in the fake_reg copies. Any code which uses macros such as incr_hp(), list_cons(), make_aligned_string(), etc. that modify the heap pointer must call restore_transient_regs() beforehand and must call save_transient_regs() afterwards. The simplest way to do this is to use the macro MR_TRACE_USE_HP() in trace/mercury_trace_util.h. The tracer may invoke Mercury code defined in the browser or library directories if that code is exported to C using `pragma export'. But any calls from functions here to code defined in Mercury and exported using `pragma export', i.e. functions starting with `ML_' prefixes, must be preceded by a call to save_registers() and followed by a call to restore_registers(). The simplest way to do this is to use the macro MR_TRACE_CALL_MERCURY() in trace/mercury_trace_util.h.