It appears msp430-elf-gcc 4.9.1 defaults to hardware multiply support for the msp430g2553 if you don't provide a choice to the command line. I didn't check other chips that lack hardware multiply. I compiled some code written for the msp430g2553 which worked fine with msp430-gcc. However, when I compiled with msp430-elf-gcc it failed to run properly on the device. Looking at the generated code I noticed it was trying use the multiply hardware.
Here is the code it generates:
0000f088 <__mulhi2>:
f088: 02 12 push r2 ;
f08a: 32 c2 dint
f08c: 03 43 nop
f08e: 82 4c 30 01 mov r12, &0x0130 ;
f092: 82 4d 38 01 mov r13, &0x0138 ;
f096: 1c 42 3a 01 mov &0x013a,r12 ;0x013a
f09a: 00 13 reti
0000f09c <__mulsihi2>:
f09c: 02 12 push r2 ;
f09e: 32 c2 dint
f0a0: 03 43 nop
f0a2: 82 4c 32 01 mov r12, &0x0132 ;
f0a6: 82 4d 38 01 mov r13, &0x0138 ;
f0aa: 1c 42 3a 01 mov &0x013a,r12 ;0x013a
f0ae: 1d 42 3c 01 mov &0x013c,r13 ;0x013c
f0b2: 00 13 reti
0000f0b4 <__umulsihi2>:
f0b4: 02 12 push r2 ;
f0b6: 32 c2 dint
f0b8: 03 43 nop
f0ba: 82 4c 30 01 mov r12, &0x0130 ;
f0be: 82 4d 38 01 mov r13, &0x0138 ;
f0c2: 1c 42 3a 01 mov &0x013a,r12 ;0x013a
f0c6: 1d 42 3c 01 mov &0x013c,r13 ;0x013c
f0ca: 00 13 reti
0000f0cc <__mulsi2>:
f0cc: 02 12 push r2 ;
f0ce: 32 c2 dint
f0d0: 03 43 nop
f0d2: 82 4c 30 01 mov r12, &0x0130 ;
f0d6: 82 4e 38 01 mov r14, &0x0138 ;
f0da: 82 4c 34 01 mov r12, &0x0134 ;
f0de: 1c 42 3a 01 mov &0x013a,r12 ;0x013a
f0e2: 92 42 3c 01 mov &0x013c,&0x013a ;0x013c
f0e6: 3a 01
f0e8: 82 4f 38 01 mov r15, &0x0138 ;
f0ec: 82 4d 34 01 mov r13, &0x0134 ;
f0f0: 82 4e 38 01 mov r14, &0x0138 ;
If I explicitly add the hardware multiply option to the command line argument,
$ msp430-elf-gcc -Wall -Os -g -mmcu=msp430g2553 -mhwmult=none ...
the code works as expected.
I tested with both the CCS supplied msp430-elf-gcc and one I built from source with the same results.
-rick
