Labels as values in gcc-2.1

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1 total messages Started by Tony Hosking Tue, 14 Apr 1992 07:58

#393

Author: Tony Hosking
Date: Tue, 14 Apr 1992 07:58

30 lines
1167 bytes

GCC version 2.1 on a DECStation 3100 running Ultrix-4.1 compiles the following
program wrongly when the -O flag is used:

#include <stdio.h>

int main (void) {
  __label__ lab;

  void *try (void) {
    return &&lab;
  }

  goto *try();
  return;
 lab:
  printf ("Hello world!\n");
}

gcc inadvertently eliminates the code at the label "lab" since it believes it
to be dead.  Surely taking the address of a label using && should indicate to
the optimizer that the code is indeed reachable!

Thanks,

		Tony Hosking
Papernet:	Dept. of Computer Science
		University of Massachusetts			 _--_|\
		Amherst, MA 01003				/      \
Voicenet:	(413) 545-0256					\_.--._/    )
Internet:	hosking@cs.umass.edu				      v    /

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