Re: Crash when launched -nw on Mac OS X, compiled with gcc 4.0.1

[Peter Dyballa]

Am 25.07.2006 um 14:15 schrieb Nick Roberts:

> > If my understanding of (old) C still stands, d is a local variable
> > inside the function's body. At line #556 a 'print d' tells:
> >
> >         $1 = {<text variable, no debug info>} 0x901aea38 <d>
>
> That's odd because your previous post said you got 527076.

Before I was working in Apple's Terminal. Then more details were  
demanded by RMS, so I needed to see the sources. The only solution  
that came to my mind was gdb in Emacs.app. And it has different  
geometry ... ?

> No.  What value does the GDB command `finish' print if starting from
> extract_float,

        (gdb) step
        extract_float (num=2) at floatfns.c:219
        (gdb) finish
        Run till exit from #0  extract_float (num=2) at floatfns.c:219
        
        Breakpoint 2, extract_float (num=4216608) at floatfns.c:220
        (gdb) finish
        Run till exit from #0  extract_float (num=4216608) at floatfns.c:220
        0x001f27dc in Fsqrt (arg=4216608) at floatfns.c:556
        Value returned is $7 = 527076
        (gdb) finish
	Run till exit from #0  0x001f27dc in Fsqrt (arg=4216608) at  
floatfns.c:556
        
	Program received signal EXC_BAD_INSTRUCTION, Illegal instruction/ 
operand.
        0x001f2828 in Fsqrt (arg=4216608) at floatfns.c:561


> or equivalently, what do you get if you type `print d'
> after
>
>    556    double d = extract_float (arg);

        Breakpoint 1, Fsqrt (arg=4216608) at floatfns.c:556
        (gdb) print d
        $5 = 7.1699012343114344e-308

> i.e at
>
>    561    IN_FLOAT (d = sqrt (d), "sqrt", arg);

        (gdb) n
        Fsqrt (arg=4216608) at floatfns.c:561
        (gdb) print d
        $1 = 527076
        (gdb) fin
        Run till exit from #0  Fsqrt (arg=4216608) at floatfns.c:561
        
	Program received signal EXC_BAD_INSTRUCTION, Illegal instruction/ 
operand.
        0x001f2828 in Fsqrt (arg=4216608) at floatfns.c:561
        (gdb) print d
        $2 = 527076

> What happens if you start Emacs as a graphical application and  
> evaluate
> (sqrt 527076) in the scratch buffer?

        pete 317 /\ ./emacs -Q --debug-init
        Fatal error (4)Illegal instruction

Between these two lines I let the X client compute the square root --  
after some seconds it crashed!

The GCC docs say about -mpowerpc-gpopt:

	The -mpowerpc option allows GCC to generate instructions that are  
found only in the 32-bit subset of the PowerPC architecture.  
Specifying -mpowerpc-gpopt implies -mpowerpc and also allows GCC to  
use the optional PowerPC architecture instructions in the General  
Purpose group, including floating-point square root. Specifying - 
mpowerpc-gfxopt implies -mpowerpc and also allows GCC to use the  
optional PowerPC architecture instructions in the Graphics group,  
including floating-point select.


Freescale documents:

	The MPC7447A processor is a high-performance, low-power, 32-bit  
implementation  of the PowerPC™ RISC architecture. Key architectural  
features include  512 KB of on-chip L2 cache, a 64-bit bus interface  
and a full 128-bit implementation  of Freescale's AltiVec™  
technology. MPC7447A processors are ideal for leading-edge computing,  
embedded network control and signal processing applications.
        
        
        Superscalar Microprocessor
        
	MPC7447A processors feature a high-frequency superscalar PowerPC  
core, capable of issuing four instructions per clock cycle (three  
instructions plus one branch) into 11 independent execution units:
                •        Four integer units (three simple plus one complex)
                •        Double-precision floating point unit
		• 	 Four AltiVec technology units (simple, complex, floating and  
permute)
                •        Load/store unit
                •        Branch processing unit

Since leaving away -mpowerpc-gpopt leads to an executable that runs  
without windows it must be either a bug in the (Apple) compiler or in  
my hardware, isn't it? (Configuring with the Fink supplied tools gcc  
4.1.0, autoconf 2.60, automake 1.9 does not seem to work.)

--
Greetings

  Pete

Math illiteracy affects 7 out of every 5 Americans.