Compiling mex files with XCode - Error using mex

I am using Matlab R2020a in conjunction with Miranda & Fackler’s CompEcon library ( https://pfackler.wordpress.ncsu.edu/compecon/154-2/ ) on a macOS Catalina operating system.

I am currently working on a Matlab script that, while it does deliver the desired results, takes an awfully long time to run through. As I was told that some functions in the CompEcon library have a C-version meant to optimize speed and memory efficiency, I figured that it would be worthwhile to make use of that.

In particular, CompEcon contains a function named mexall that is designed to compile all available mex files. So, in order to be able to run mexall, I downloaded and installed Xcode 12 as a compiler such that when I type

mex -setup C 

Matlab says

MEX configured to use 'Xcode with Clang' for C language compilation.

Running the actual mexall function, however, generates a fair amount of warnings and finally an error to the effect that:

Error using mex
/Applications/CompEcon/CEtools/lusolve.c:35:13: error: implicitly declaring library function 'memcpy'
with type 'void *(void *, const void *, unsigned long)' [-Werror,-Wimplicit-function-declaration]
  if (x!=b) memcpy(x,b,n*sizeof(double));
            ^
/Applications/CompEcon/CEtools/lusolve.c:35:13: note: include the header <string.h> or explicitly provide
a declaration for 'memcpy'
/Applications/CompEcon/CEtools/lusolve.c:154:7: warning: incompatible pointer types assigning to 'int *'
from 'mwIndex *' (aka 'unsigned long *') [-Wincompatible-pointer-types]
    Ri=mxGetIr(prhs[0]);
      ^~~~~~~~~~~~~~~~~
4 warnings and 1 error generated.

Error in mexall (line 26)
  mex(files(i).name)

Nonetheless, it would seem that running mexall did generate quite a few mexmaci64-file for the m-files that have a corresponding C-version.

So, when I attempt to run my script despite the ocurrence of the error above, it takes a couple of seconds and then Matlab crashes with an error report that reads:

  MATLAB crash file:/Users/username/matlab_crash_dump.4849-4:

--------------------------------------------------------------------------------
         Illegal instruction detected at Sat Sep 26 16:53:40 2020 -0400
--------------------------------------------------------------------------------

Configuration:
  Crash Decoding           : Disabled - No sandbox or build area path
  Crash Mode               : continue (default)
  Default Encoding         : UTF-8
  Deployed                 : false
  Graphics Driver          : Unknown hardware 
  Java Version             : Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
  MATLAB Architecture      : maci64
  MATLAB Entitlement ID    : 1495108
  MATLAB Root              : /Applications/MATLAB_R2020a.app
  MATLAB Version           : 9.8.0.1417392 (R2020a) Update 4
  OpenGL                   : hardware
  Operating System         : Mac OS Version 10.15.6 (Build 19G2021)
  Process ID               : 4849
  Processor ID             : x86 Family 6 Model 142 Stepping 9, GenuineIntel
  Session Key              : 6b43dc2e-7af0-4b10-9041-1f84c68a7111
  Window System            : Quartz

Fault Count: 4


Abnormal termination:
Illegal instruction

Register State (from fault):
  RAX = a7066b851e5d0047  RBX = 00000000ffffffff
  RCX = 00007fff6fb01d2e  RDX = 0000000000001000
  RSP = 0000700010cf6290  RBP = 0000700010cf6290
  RSI = 00000001368b8000  RDI = 0000000000000103

   R8 = 0000000000000000   R9 = 0000000000000000
  R10 = 00000001368b8080  R11 = 0000000000000246
  R12 = 0000600006811798  R13 = 00000000fce74800
  R14 = 000060000665c000  R15 = 0000000110032058

  RIP = 00007fff6fb96f3e  RFL = 0000000000010202

   CS = 000000000000002b   FS = 0000000000000000   GS = 0000000000000000

Stack Trace (from fault):

This error message goes on and on for 34 lines.

I would very much appreciate any pointers as to how I could resolve this issue. Please let me know if you need any additional information.

Many thanks.

Answer 1

[Walter Roberson]

/Applications/CompEcon/CEtools/lusolve.c needs to have

#include <string.h>

added near the top.

/Applications/CompEcon/CEtools/lusolve.c needs to have the declaration for Ri changed from int * to mwIndex *

We can tell that the code was written in the days when 32 bit pointers were used. There might be additional similar problems lurking around.

[Jon B.]

Thank you so much for your reply. Exactly the hint I needed. It would seem that there has been an effort to modify the mex files to be able to run in a 64 bit environment. Downloading the updated package did resolve all my problems.