Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!sdd.hp.com!mips!hal!mark From: mark@mips.COM (Mark G. Johnson) Newsgroups: comp.sys.sgi Subject: Re: C compiler bug Summary: Sun SPARCstation 1 and Apollo DN4000 give same "wrong" answer as SGI Iris -- perhaps it isn't actually wrong (??) Message-ID: <40159@mips.mips.COM> Date: 14 Jul 90 19:52:16 GMT References: <9007131953.AA08463@prism> Sender: news@mips.COM Reply-To: mark@mips.COM (Mark G. Johnson) Organization: MIPS Computer Systems, Inc. Lines: 79 In article <9007131953.AA08463@prism> ae504pw@prism.gatech.edu writes: >I believe I may have found a bug in the C compiler on the Iris. >I compiled the following program, taken from the April 1985 >PC Tech Journal ... > > [code for "High Performance CRC Computation Routine" removed] > >Something is definitely amiss here! On a whim I compiled and ran >the identical code on a Sequent S81. The results in that case are >quite different as seen below. > Lint found little to complain about, so I tried the experiment of compiling and running the program on a Sun SPARCstation 1, an Apollo DN4000, and a MIPS RC3240. All three of these produced the same output as the IRIS. So the scorecard thus far is: Printed the result Printed the result that John Forrest wanted John Forrest didn't want --------------------------------------------------------------------------- Sequent S81 DYNIX V3.0.17.9 SGI Iris 4D/120GTX Irix 3.2 Sun SPARCstation 1 SunOs 4.0.3c MIPS RC3240 RISC/os 4.50 Apollo DN4000 BSD 4.2 DOMAIN-IX The "wrong answer" machines contain 4 different CPUs (R2000, Cy7C601, R3000, 68020) and employ 3 different C compilers. Here is the output from the SPARCstation 1. "diff" says it is identical to the DN4000 and the RC3240 output. 00 - 0000 0000 0000 0000 0000 0000 0000 0000 08 - 0000 0000 0000 0000 0000 0000 0000 0000 10 - 0000 0000 0000 0000 0000 0000 0000 0000 18 - 0000 0000 0000 0000 0000 0000 0000 0000 20 - 0000 0000 0000 0000 0000 0000 0000 0000 28 - 0000 0000 0000 0000 0000 0000 0000 0000 30 - 0000 0000 0000 0000 0000 0000 0000 0000 38 - 0000 0000 0000 0000 0000 0000 0000 0000 40 - 0000 0000 0000 0000 0000 0000 0000 0000 48 - 0000 0000 0000 0000 0000 0000 0000 0000 50 - 0000 0000 0000 0000 0000 0000 0000 0000 58 - 0000 0000 0000 0000 0000 0000 0000 0000 60 - 0000 0000 0000 0000 0000 0000 0000 0000 68 - 0000 0000 0000 0000 0000 0000 0000 0000 70 - 0000 0000 0000 0000 0000 0000 0000 0000 78 - 0000 0000 0000 0000 0000 0000 0000 0000 80 - 0000 0000 0000 0000 0000 0000 0000 0000 88 - 0000 0000 0000 0000 0000 0000 0000 0000 90 - 0000 0000 0000 0000 0000 0000 0000 0000 98 - 0000 0000 0000 0000 0000 0000 0000 0000 a0 - 0000 0000 0000 0000 0000 0000 0000 0000 a8 - 0000 0000 0000 0000 0000 0000 0000 0000 b0 - 0000 0000 0000 0000 0000 0000 0000 0000 b8 - 0000 0000 0000 0000 0000 0000 0000 0000 c0 - 0000 0000 0000 0000 0000 0000 0000 0000 c8 - 0000 0000 0000 0000 0000 0000 0000 0000 d0 - 0000 0000 0000 0000 0000 0000 0000 0000 d8 - 0000 0000 0000 0000 0000 0000 0000 0000 e0 - 0000 0000 0000 0000 0000 0000 0000 0000 e8 - 0000 0000 0000 0000 0000 0000 0000 0000 f0 - 0000 0000 0000 0000 0000 0000 0000 0000 f8 - 0000 0000 0000 0000 0000 0000 0000 0000 TestArray1 CRC = 0x0000 TestArray2 CRC = 0x0000 Text = [This is a test message.] CRC = 0000 -- -- Mark Johnson MIPS Computer Systems, 930 E. Arques M/S 2-02, Sunnyvale, CA 94086 (408) 524-8308 mark@mips.com {or ...!decwrl!mips!mark}