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ITE and binary relations are constant when all operands are constants #7569

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Merged
merged 1 commit into from
Mar 6, 2023
Merged

ITE and binary relations are constant when all operands are constants #7569

merged 1 commit into from
Mar 6, 2023

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tautschnig
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This expands the definition of is_constantt to cover if-then-else as well as binary relations. In many, but not, cases the simplifier will have turned these into simpler constants. The included regression test is derived from Rust code, where the intermediate representation (together with constant propagation) will yield such comparisons.

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@tautschnig tautschnig added aws Bugs or features of importance to AWS CBMC users Kani Bugs or features of importance to Kani Rust Verifier labels Mar 1, 2023
@tautschnig tautschnig mentioned this pull request Mar 1, 2023
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peterschrammel
peterschrammel approved these changes Mar 2, 2023
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Does the same reasoning also apply to further operators such as bitwise and boolean operators?

@peterschrammel peterschrammel removed their assignment Mar 2, 2023
@tautschnig tautschnig assigned tautschnig and unassigned kroening Mar 2, 2023
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Does the same reasoning also apply to further operators such as bitwise and boolean operators?

Good call. Doing something like ptr & 0xF for alignment checks would be such an example that we can safely constant-propagate (once ptr is found to be &object by other constant propagation). Added.

@tautschnig tautschnig force-pushed the feature/more-constants branch from f926d2b to 8f1677a Compare March 2, 2023 20:58
@tautschnig
ITE and binary relations are constant when all operands are constants
0289d31 
This expands the definition of is_constantt to cover if-then-else as
well as binary relations and logic or bit operations. In many, but not,
cases the simplifier will have turned these into simpler constants. The
included regression test is derived from Rust code, where the
intermediate representation (together with constant propagation) will
yield such comparisons.
@tautschnig tautschnig force-pushed the feature/more-constants branch from 8f1677a to 0289d31 Compare March 6, 2023 14:50
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codecov bot commented Mar 6, 2023

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.10 🎉

Comparison is base (e024ecb) 78.39% compared to head (0289d31) 78.50%.

Additional details and impacted files 
@@             Coverage Diff             @@
##           develop    #7569      +/-   ##
===========================================
+ Coverage    78.39%   78.50%   +0.10%     
===========================================
  Files         1670     1670              
  Lines       191760   191764       +4     
===========================================
+ Hits        150337   150544     +207     
+ Misses       41423    41220     -203
Impacted Files Coverage Δ
src/util/expr_util.cpp 91.20% <100.00%> (+0.19%) ⬆️
src/util/bitvector_expr.h 97.41% <0.00%> (+0.46%) ⬆️
src/util/symbol_table.cpp 91.30% <0.00%> (+6.52%) ⬆️
src/util/type.h 100.00% <0.00%> (+7.46%) ⬆️
src/util/string_container.h 100.00% <0.00%> (+9.09%) ⬆️
src/util/ssa_expr.h 100.00% <0.00%> (+11.36%) ⬆️
src/util/validate_expressions.cpp 93.75% <0.00%> (+18.75%) ⬆️
src/big-int/bigint.cc 89.00% <0.00%> (+20.50%) ⬆️
src/util/validate_helpers.h 100.00% <0.00%> (+22.22%) ⬆️
src/util/string_container.cpp 51.85% <0.00%> (+27.77%) ⬆️
... and 3 more

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@tautschnig tautschnig merged commit 014188e into diffblue:develop Mar 6, 2023
@tautschnig tautschnig deleted the feature/more-constants branch March 6, 2023 19:08
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@peterschrammel peterschrammel peterschrammel approved these changes

@TGWDB TGWDB TGWDB approved these changes

@kroening kroening Awaiting requested review from kroening kroening is a code owner

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@tautschnig tautschnig

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