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Re: More methods of reducing the register pressure

On 04/19/2015 09:28 AM, Ajit Kumar Agarwal wrote:
Hello All:

To reduce the register pressure, I am proposing the following methods of reducing the registers.

1. Assigning same registers or sharing same register for the logical registers having the same value.
To determine the logical registers having the same value is the real challenge. Is there is any way in
GCC to determine the logical registers having the same value?
I believe Vlad looked at this 10+ years ago and it was of marginal/no real benefit.

2. For the architecture with the self-modifying instructions the DEF-USE will not overlap and can
Do the better register allocator and thus reclaiming the registers when it's no longer used.
Such self-modifying instructions can assign the same registers.

For example:

OP R1   -------------Definition.
...                                      .
...                                      No used.
OP R1,R1 ----------------self-modifying.
.....                                           .
......                                         Not Used
OP R1, R1 ------------  Self-modifying.
I would think this would be handled by the normal life & conflict analysis which works on pseudos.


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