mirror of
https://github.com/Mercury-Language/mercury.git
synced 2026-04-15 01:13:30 +00:00
72f174b4e2
The majority of calls to MR_fatal_error do not follow an operation that sets errno, so printing out an error message unrelated to the reason for the fatal error will lead to confusion. It can also cause test failures if errno happens to be set to non-zero some time prior to an expected call to MR_fatal_error. Fixes bug #464. runtime/mercury_misc.c: Don't print value of errno in MR_fatal_error. runtime/mercury_context.c: runtime/mercury_thread.c: Pass strerror strings to MR_fatal_error where appropriate. runtime/mercury_memory_zones.c: runtime/mercury_memory_zones.h: Pass strerror strings to MR_fatal_error following failures of MR_protect_pages. Document that this assumes MR_protect_pages sets errno on error. Skip unnecessary call to sprintf before MR_fatal_error. runtime/mercury_deep_profiling.c: Skip unnecessary call to sprintf before MR_fatal_error. Reduce size of some buffers. runtime/mercury_overflow.c: runtime/mercury_stack_trace.c: Pass a fixed format string to MR_fatal_error just in case the message string may contain percentage signs. runtime/mercury_tabling.c: Skip unnecessary call to sprintf before MR_fatal_error. deep_profiler/timeout.m: library/thread.m: mdbcomp/shared_utilities.m: Pass strerror strings to MR_fatal_error where appropriate. trace/mercury_trace.c: Skip unnecessary call to sprintf before MR_fatal_error. trace/mercury_trace_external.c: Pass a fixed format string to MR_fatal_error just in case.
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.