Get rvalue bounds for the value of lvalue expressions from the CheckingState#1183
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September 8, 2021 14:05
…ue and ArrayToPointerDecay casts
… or decrement operator
… compound assignment
… observed bounds of s->a
…ds of q before the decrement q-- in the "false" conditional arm
… compound assignment p += 2 are bounds(p, p + (i - 1))
… expression for certain AbstractSets changed Since getting the observed bounds for expressions that appear on the RHS of assignments happens before updating the observed bounds of expressions that appear on the LHS, an AbstractSet is created for an expression on the RHS of an assignment before the expression on the LHS.
…->a after updating its observed bounds
This was referenced Sep 9, 2021
This was referenced Jan 15, 2022
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This PR modifies the way that rvalue bounds are determined for the value of a member expression, pointer deference, or array subscript to be consistent with the way that rvalue bounds are determined for the value of a variable. The rvalue bounds for the value of a variable, member expression, pointer dereference, or array subscript expression
eare determined by looking at theObservedBoundsmap in the checking state. If theAbstractSetcontainingeis present inObservedBounds, then those are the bounds for the value ofe. Otherwise, the bounds for the value ofedefault to the lvalue target bounds ofe(or the lvalue bounds ofeifeis the subexpression of anArrayToPointerDecaycast.One consequence of this change is that the order of expressions used to get or create an
AbstractSetmay differ, which may affect the representative expression for theAbstractSet. For example, consider the assignment*p = p[0] + 1. The rvalue bounds ofp[0]are determined before modifying the observed bounds of*p. This means thatp[0]is the first expression that is used to create theAbstractSetthat contains*pandp[0], sop[0]is the representative expression for thisAbstractSet.This PR also includes a minor fix in CanonBounds where
ExtVectorElementExprsare compared by address. This prevents anllvm_unreachablethat would otherwise occur when creating anAbstractSetfor a member expression that contains anExtVectorElementExpr.