Bug report and patch to suggest on triggering related to optimizing out a great deal of code

[Jeffrey A Law]

  In message < 200001011409.PAA09183@loewis.home.cs.tu-berlin.de >you write:
  > > attached is compressed mon.i.gz file
  > > 
  > > Here is the patch in action:
  > > 
  > > [david@lucy color_mon]$ cc -I/m/include -I/usr/include -O -c mon.c -o
  > > mon.o -
  > > -save-temps
  > > mon.c: In function `main':
  > > mon.c:839: warning: optimizing out a lot of code: try without -O switch
  > > mon.c:839: Internal compiler error in `build_insn_chain', at
  > > global.c:1758
  > 
  > Thanks again for your bug report. I have simplified your testcase a
  > bit (see below), but I could not figure out how to fix the bug. Please
  > note that it only occurs with -O; it works fine with -O2.
  > 
  > Regards,
  > Martin
  > 
  > main(int na, char* argv[])
  > {
  > 	int wflg = 0, tflg = 0;
  > 	int dflg = 0;
  > 	exit(0);
  > 	while(1)
  > 	{
  > 		switch(argv[1][0])
  > 		{
  > 			help:
  > 				exit(0);
  > 			case 'w':
  > 			case 'W':
  > 				wflg = 1;
  > 				break;
  > 			case 't':
  > 			case 'T':
  > 				tflg = 1;
  > 				break;
  > 			case 'd':
  > 				dflg = 1;
  > 				break;
  > 		}
  > 	}
  > }
FWIW, I put this test into the regression testsuite.

jeff