Difference between C5502 and C5504 assembly code

Hi Yiyuan,

The core of the C5502 is Rev 3.0 Rev 2.2 [EDIT] and the core of the C5505 is Rev 3.3.

These documents may reveal the difference

C5505 CPU Ref Guide:http://www.ti.com/lit/ug/swpu073e/swpu073e.pdf

C5502 CPU Ref Guide: http://www.ti.com/lit/ug/spru371f/spru371f.pdf

C5505 Mnemonic Instruction Set Reference Guide: http://www.ti.com/lit/ug/swpu067e/swpu067e.pdf

C5502 Mnemonic Instruction Set Reference Guide: http://www.ti.com/lit/ug/spru374g/spru374g.pdf

I can look into it more tomorrow.

Hope this helps,
Mark

 I should also mention that the C5505 is the same as the C5504 in terms of core and instruction set.

-Mark

We already did a comparison between the instructions of the 2 cores, and we can see more instructions for C5504 than C5502, but C5504 is a superset of C5502, and all instructions of C5502 we’re using are in C5504. We didn’t review each instruction to see if the behavior is different although the instructions are the same.

What we need at this point is someone with deep understanding of the cores and their behavior.

The 5502 assembly code should work fine on 5504 since the 5504, as you pointed out, is a superset in terms of its instruction set.  My best guess would be that your original function is not properly observing the C calling conventions, i.e. it fails to properly preserve a register.  You were probably "lucky" that in your 5502 function the parent function did not actually utilize the unpreserved register and so there was no ill effect.  However, it's very easy/likely for the same function to be used elsewhere and have things suddenly fail.

Please see section 6.3 "Register Conventions" of the 55x Compiler Guide.  It tells you for every register whether it should be preserved by the parent function or the child function.