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Re: More methods of reducing the register pressure
- From: Jeff Law <law at redhat dot com>
- To: Ajit Kumar Agarwal <ajit dot kumar dot agarwal at xilinx dot com>, "vmakarov at redhat dot com" <vmakarov at redhat dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Cc: Vinod Kathail <vinodk at xilinx dot com>, Shail Aditya Gupta <shailadi at xilinx dot com>, Vidhumouli Hunsigida <vidhum at xilinx dot com>, Nagaraju Mekala <nmekala at xilinx dot com>
- Date: Sun, 19 Apr 2015 11:11:11 -0600
- Subject: Re: More methods of reducing the register pressure
- Authentication-results: sourceware.org; auth=none
- References: <5796c43e-1add-48f1-9b1e-63f373eef93f at BL2FFO11OLC007 dot protection dot gbl>
On 04/19/2015 09:28 AM, Ajit Kumar Agarwal wrote:
I believe Vlad looked at this 10+ years ago and it was of marginal/no
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 would think this would be handled by the normal life & conflict
analysis which works on pseudos.
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.
OP R1 -------------Definition.
... No used.
OP R1,R1 ----------------self-modifying.
...... Not Used
OP R1, R1 ------------ Self-modifying.