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Optimise selectorBase, similar to existing work on implicitFieldRead

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This commit is contained in:
Chris Smowton
2021-03-16 14:54:45 +00:00
committed by Owen Mansel-Chan
parent 8cde56dfc2
commit 660ba4e31c
1 changed files with 42 additions and 18 deletions
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60
ql/src/semmle/go/controlflow/IR.qll
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@@ -238,20 +238,13 @@ module IR {
}
}
/**
* Gets the effective base of a selector, index or slice expression, taking implicit dereferences
* and implicit field reads into account.
*
* For a selector expression `b.f`, this could be the implicit dereference `*b`, or the implicit
* field access `b.Embedded.f` if the field `f` is promoted from an embedded type `Embedded`, or
* a combination of both, or simply `b` if neither case applies.
*/
private Instruction selectorBase(Expr e) {
exists(Field field | e.(SelectorExpr).refersTo(field) | result = selectorBase(e, field))
or
private Instruction simpleSelectorBase(Expr e) {
exists(Expr base |
base = e.(SelectorExpr).getBase() and
e.(SelectorExpr).refersTo(any(Method m))
(
e.(SelectorExpr).refersTo(any(Method m)) or
e.(SelectorExpr).refersTo(any(Field f | not f instanceof PromotedField))
) and
base = e.(SelectorExpr).getBase()
or
base = e.(IndexExpr).getBase()
or
@@ -264,11 +257,34 @@ module IR {
)
}
private Instruction selectorBase(SelectorExpr se, Field field) {
exists(Type baseType, StructType baseStructType |
baseType = se.getBase().getType().getUnderlyingType() and
baseStructType = [baseType, baseType.(PointerType).getBaseType().getUnderlyingType()]
|
/**
* Gets the effective base of a selector, index or slice expression, taking implicit dereferences
* and implicit field reads into account.
*
* For a selector expression `b.f`, this could be the implicit dereference `*b`, or the implicit
* field access `b.Embedded.f` if the field `f` is promoted from an embedded type `Embedded`, or
* a combination of both, or simply `b` if neither case applies.
*/
private Instruction selectorBase(Expr e) {
result = promotedFieldSelectorBase(e, _)
or
result = simpleSelectorBase(e)
}
private class PromotedField extends Field {
PromotedField() { this = any(StructType t).getFieldOfEmbedded(_, _, _, _) }
}
private class PromotedFieldSelector extends SelectorExpr {
PromotedFieldSelector() { this.refersTo(any(PromotedField f)) }
}
private Type getSelectedStructType(PromotedFieldSelector e) {
pragma[only_bind_into](result) = e.getBase().getType().getBaseType*().getUnderlyingType()
}
private Instruction promotedFieldSelectorBase(PromotedFieldSelector se, Field field) {
exists(StructType baseStructType | baseStructType = getSelectedStructType(se) |
if field = baseStructType.getOwnField(_, _)
then
result = MkImplicitDeref(se.getBase())
@@ -291,6 +307,14 @@ module IR {
)
}
private Instruction selectorBase(SelectorExpr se, Field field) {
result = promotedFieldSelectorBase(se, field)
or
se.refersTo(field) and
result = simpleSelectorBase(se) and
not field instanceof PromotedField
}
/**
* An IR instruction that reads a component from a composite object.
*