Byte extract and extract bits can be constant

[tautschnig]

When all operands are constants and the extract is fully within bounds of the source object then the result is constant.

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[codecov]

Codecov Report

Base: 78.34% // Head: 78.33% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (2ba7118) compared to base (a53fa0f).
Patch coverage: 89.51% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7331      +/-   ##
===========================================
- Coverage    78.34%   78.33%   -0.01%     
===========================================
  Files         1644     1645       +1     
  Lines       190313   190392      +79     
===========================================
+ Hits        149097   149153      +56     
- Misses       41216    41239      +23     

Impacted Files	Coverage Δ
jbmc/src/janalyzer/janalyzer_parse_options.cpp	48.58% <ø> (ø)
.../src/java_bytecode/character_refine_preprocess.cpp	54.27% <ø> (ø)
...mc/src/java_bytecode/character_refine_preprocess.h	100.00% <ø> (ø)
jbmc/src/java_bytecode/ci_lazy_methods.h	100.00% <ø> (ø)
jbmc/src/java_bytecode/ci_lazy_methods_needed.cpp	98.41% <ø> (ø)
jbmc/src/java_bytecode/ci_lazy_methods_needed.h	100.00% <ø> (ø)
jbmc/src/java_bytecode/code_with_references.cpp	84.61% <ø> (ø)
jbmc/src/java_bytecode/java_bmc_util.cpp	100.00% <ø> (ø)
...mc/src/java_bytecode/java_bytecode_convert_class.h	0.00% <ø> (ø)
...src/java_bytecode/java_bytecode_convert_method.cpp	97.69% <ø> (ø)
... and 420 more

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[kroening]

I'd be curious in which cases these are "considered constant" but not simplified to proper constants?

[tautschnig]

I'd be curious in which cases these are "considered constant" but not simplified to proper constants?

The case motivating this is turning a pointer into a sequence of bytes (as happens with memcpy).

[kroening]

Independently, memcpy should become smarter.