[m-rev.] for review: instmap_delta_restrict

[Julien Fischer]

On Fri, 1 Apr 2022, Zoltan Somogyi wrote:

> For review by anyone. I am mostly seeking feedback on
> the names of the new library predicates, and whether they
> should be in the documented part of the interface or not.
> If yes, I intend to add an entry to NEWS with the final name.
>
> Julien, if you have a server machine free, you may want to benchmark
> this change. On my laptop, the difference is lost in thermal
> throttling noise.

Results of speedtest -g hlc.gc for a few configurations attached.  They're 
not really any more informative.

Julien.
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EXTRA_MCFLAGS = -O2
GRADE = asm_fast.gc
mercury_compile.01 average of 6 with ignore=1     10.62
EXTRA_MCFLAGS = -O2 --intermod-opt
GRADE = asm_fast.gc
mercury_compile.02 average of 6 with ignore=1      9.74
EXTRA_MCFLAGS = -O2
GRADE = hlc.gc
mercury_compile.03 average of 6 with ignore=1     11.04
EXTRA_MCFLAGS = -O2 --intermod-opt
GRADE = hlc.gc
mercury_compile.04 average of 6 with ignore=1     10.37
-------------- next part --------------
EXTRA_MCFLAGS = -O2
GRADE = asm_fast.gc
mercury_compile.01 average of 6 with ignore=1     10.73
EXTRA_MCFLAGS = -O2 --intermod-opt
GRADE = asm_fast.gc
mercury_compile.02 average of 6 with ignore=1      9.74
EXTRA_MCFLAGS = -O2
GRADE = hlc.gc
mercury_compile.03 average of 6 with ignore=1     10.96
EXTRA_MCFLAGS = -O2 --intermod-opt
GRADE = hlc.gc
mercury_compile.04 average of 6 with ignore=1     10.24