This replaces the old approach of fingerprinting every AST node into a string,
which avoided collisions and was simple to implement, but turned out to be
extremely ineffective with respect to both performance and memory.
The collisions are now dealt with in a separate pass, which no longer causes
performance problems because collisions are rare.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D22515
llvm-svn: 279378
So far macro-generated code was treated by the CloneDetector as normal code.
This caused that some macros where reported as false-positive clones because
large chunks of code coming from otherwise concise macro expansions were treated
as copy-pasted code.
This patch ensures that macros are treated in the same way as literals/function
calls. This prevents macros that expand into multiple statements
from being reported as clones.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D23316
llvm-svn: 279367
For example, code samples `isa<Stmt>(S)' and `isa<Expr>(S)'
are no longer considered to be clones.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D23555
llvm-svn: 279366
The original clone checker tries to find copy-pasted code that is exactly
identical to the original code, up to minor details.
As an example, if the copy-pasted code has all references to variable 'a'
replaced with references to variable 'b', it is still considered to be
an exact clone.
The new check finds copy-pasted code in which exactly one variable seems
out of place compared to the original code, which likely indicates
a copy-paste error (a variable was forgotten to be renamed in one place).
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D23314
llvm-svn: 279056
CallExpr may have a null direct callee when the callee function is not
known in compile-time. Do not try to take callee name in this case.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D23320
llvm-svn: 278238
CloneDetector should be able to detect clones with renamed variables.
However, if variables are referenced multiple times around the code sample,
the usage patterns need to be recognized.
For example, (x < y ? y : x) and (y < x ? y : x) are no longer clones,
however (a < b ? b : a) is still a clone of the former.
Variable patterns are computed and compared during a separate filtering pass.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D22982
llvm-svn: 277757
So far the CloneDetector only respected the kind of each statement when
searching for clones. This patch refines the way the CloneDetector collects data
from each statement by providing methods for each statement kind,
that will read the kind-specific attributes.
For example, statements 'a < b' and 'a > b' are no longer considered to be
clones, because they are different in operation code, which is an attribute
specific to the BinaryOperator statement kind.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D22514
llvm-svn: 277449
This patch adds the CloneDetector class which allows searching source code
for clones.
For every statement or group of statements within a compound statement,
CloneDetector computes a hash value, and finds clones by detecting
identical hash values.
This initial patch only provides a simple hashing mechanism
that hashes the kind of each sub-statement.
This patch also adds CloneChecker - a simple static analyzer checker
that uses CloneDetector to report copy-pasted code.
Patch by Raphael Isemann!
Differential Revision: https://reviews.llvm.org/D20795
llvm-svn: 276782
Artem Dergachev