On Thu, Mar 1, 2012 at 12:57 PM, gosplan <gosp...@gmail.com> wrote:
> Can someone explain to me, this is a compilation error in the experimental
> branch MSPGCC, or some feature of the compiler?
Compiler bug, fixed in 20120311.
Peter
> int main(void)
> {
> WDTCTL=WDTPW|WDTTMSEL|WDTSSEL|WDTIS0;
>
> volatile uint8_t a, b, c;
>
> a=0b10000111;
> b=0b10000101;
>
> if((a^b)&0x80) c=0xAA; //checking MSB (a xor b), must be 0
> else c=0xBB;
>
> if(c==0xAA) led_on();
> /*
> In experimental version of GCC (mspgcc-20120224-experimental) this
> condition is TRUE, while should be FALSE.
> Stable version mspgcc-20110716-p20111105 works correctly (condition is
> FALSE)
> */
> }
>
> ASM listing:
>
> ---mspgcc-20120224-experimental:
> a=0b10000111;
> cc8c: f1 40 87 ff mov.b #-121, 2(r1) ;#0xff87, 0x0002(r1)
> cc90: 02 00
> b=0b10000101;
> cc92: f1 40 85 ff mov.b #-123, 1(r1) ;#0xff85, 0x0001(r1)
> cc96: 01 00
>
> if((a^b)&0x80) c=0xAA;
> cc98: 5e 41 02 00 mov.b 2(r1), r14 ;0x0002(r1)
> cc9c: 5f 41 01 00 mov.b 1(r1), r15 ;0x0001(r1)
> cca0: 4f ee xor.b r14, r15
> cca2: 04 34 jge $+10 ;abs 0xccac <---------
> cca4: f1 40 aa ff mov.b #-86, 0(r1) ;#0xffaa, 0x0000(r1)
> cca8: 00 00
> ccaa: 03 3c jmp $+8 ;abs 0xccb2
> else c=0xBB;
> ccac: f1 40 bb ff mov.b #-69, 0(r1) ;#0xffbb, 0x0000(r1)
> ccb0: 00 00
>
> ---mspgcc-20110716-p20111105:
> a=0b10000111;
> ccda: f1 40 87 ff mov.b #-121, 0(r1) ;#0xff87, 0x0000(r1)
> ccde: 00 00
> b=0b10000101;
> cce0: f1 40 85 ff mov.b #-123, 1(r1) ;#0xff85, 0x0001(r1)
> cce4: 01 00
>
> if((a^b)&0x80) c=0xAA;
> cce6: 5f 41 01 00 mov.b 1(r1), r15 ;0x0001(r1)
> ccea: 6f e1 xor.b @r1, r15
> ccec: 4f 93 tst.b r15 <---------
> ccee: 04 34 jge $+10 ;abs 0xccf8
> ccf0: f1 40 aa ff mov.b #-86, 2(r1) ;#0xffaa, 0x0002(r1)
> ccf4: 02 00
> ccf6: 03 3c jmp $+8 ;abs 0xccfe
> else c=0xBB;
> ccf8: f1 40 bb ff mov.b #-69, 2(r1) ;#0xffbb, 0x0002(r1)
> ccfc: 02 00
>
> :: mailto:gosp...@gmail.com
>
>
> ------------------------------------------------------------------------------
> Virtualization & Cloud Management Using Capacity Planning
> Cloud computing makes use of virtualization - but cloud computing
> also focuses on allowing computing to be delivered as a service.
> http://www.accelacomm.com/jaw/sfnl/114/51521223/
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------------------------------------------------------------------------------
Virtualization & Cloud Management Using Capacity Planning
Cloud computing makes use of virtualization - but cloud computing
also focuses on allowing computing to be delivered as a service.
http://www.accelacomm.com/jaw/sfnl/114/51521223/
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