Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!csd4.milw.wisc.edu!indri!eta!nic.MR.NET!umn-d-ub!umn-cs!mmm!manning
From: manning@mmm.UUCP (Arthur T. Manning)
Newsgroups: comp.os.os9
Subject: C compiler 3.0 BUG with inline assembly!
Summary: semicolons DO have a purpose all by themselves
Keywords: #asm, #endasm, crackerjack_compiler
Message-ID: <1248@mmm.UUCP>
Date: 6 Apr 89 03:44:35 GMT
Reply-To: manning@mmm.UUCP (Arthur T. Manning)
Followup-To: flame Microware for not telling you about this
Distribution: usa
Organization: 3M Engineering Systems & Technology Lab, St. Paul MN
Lines: 38

In the following code, the compiler concatenates the two SEPERATE sections
of assembly together as though they were all inside the if statement's
scope.  In the second case (with only a semicolon added) the compiler does
what it is expected to do.  Apparently "}" is not enough for the compiler
to know that the if{} has ended and to put the rest of the assembly code
outside the scope.

Would you believe we found this bug in an interrupt service routine?

We would never have found it without our VMETRO vme bus debugger.

if(foo) {
#asm
        move.l  a1,a2
#endasm
} /* end of if's scope, right? */
/* Wrong! The compiler doesn't think so, and puts these together. */
#asm
        move.l  a2,a3
#endasm

if(foo) {
#asm
        move.l  a1,a2
#endasm
}
; /* REALLY the end of if's scope */
/* the compiler knows now that the semicolon is there... */
#asm
        move.l  a2,a3
#endasm



-- 
Arthur T. Manning                                Phone: 612-733-4401
3M Center  518-1                                 FAX:   612-736-3122
St. Paul  MN  55144-1000   U.S.A.                Email: manning@mmm.uucp