Correctly determine bounds for predefined literals #673
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This is WIP. I will soon add comments and unit tests to this patch. |
mgrang
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Have asked @Machiry to verify whether this fixes the issue he reported. |
added 2 commits
August 23, 2019 11:43
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Added a simple test case. Will add more complex ones soon. |
mgrang
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Run time tests for predefined literals added in checkedc/checkedc#380. |
dtarditi
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Aug 26, 2019
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For a string literal expression, we always bind the result of the expression to a temporary. We then use this temporary in the bounds expression for the string literal expression. Unfortunately, I think you need to do something similar here. Otherwise, a runtime bounds check based on accessing the predefined expression could be incorrect: the base value could be different for the lower and upper bounds.
mgrang
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Sep 27, 2019
Cherry-picked from commit 6252abb Correctly determine bounds for predefined literals. Section 6.4.2.2 of the C11 Standard defines predefined identifiers: the special identifier __func__ evaluates to a string that is the name of the current function. In clang, predefined identifiers are represented using the PredefinedExpr class, which wraps a string literal. The PredefinedExpr class evaluates to an lvalue that is the address of the string literal. To represent bounds information, follow the same pattern that we use for string literals:. Bind the result of the PredefinedExpr class to a temporary and use the temporary in the bounds of the expression. We considered having the class wrap a temporary expression, but that causes existing tests of predefined literals to break and requires more changes to the compiler logic for predefined expressions.
mgrang
pushed a commit
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Sep 27, 2019
Cherry-picked from commit 6252abb Correctly determine bounds for predefined literals. Section 6.4.2.2 of the C11 Standard defines predefined identifiers: the special identifier __func__ evaluates to a string that is the name of the current function. In clang, predefined identifiers are represented using the PredefinedExpr class, which wraps a string literal. The PredefinedExpr class evaluates to an lvalue that is the address of the string literal. To represent bounds information, follow the same pattern that we use for string literals:. Bind the result of the PredefinedExpr class to a temporary and use the temporary in the bounds of the expression. We considered having the class wrap a temporary expression, but that causes existing tests of predefined literals to break and requires more changes to the compiler logic for predefined expressions.
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This fixes issue #650 .