Commit Graph

10 Commits

Author SHA1 Message Date
Dmitri Gribenko 5689b38c6a Removed a RecursiveASTVisitor feature to visit operator kinds with different methods
Summary:
This feature was only used in two places, but contributed a non-trivial
amount to the complexity of RecursiveASTVisitor, and was buggy (see my
recent patches where I was fixing the bugs that I noticed). I don't
think the convenience benefit of this feature is worth the complexity.

Besides complexity, another issue with the current state of
RecursiveASTVisitor is the non-uniformity in how it handles different
AST nodes. All AST nodes follow a regular pattern, but operators are
special -- and this special behavior not documented. Correct usage of
RecursiveASTVisitor relies on shadowing member functions with specific
names and signatures. Near misses don't cause any compile-time errors,
incorrectly named or typed methods are just silently ignored. Therefore,
predictability of RecursiveASTVisitor API is quite important.

This change reduces the size of the `clang` binary by 38 KB (0.2%) in
release mode, and by 7 MB (0.3%) in debug mode. The `clang-tidy` binary
is reduced by 205 KB (0.3%) in release mode, and by 5 MB (0.4%) in debug
mode. I don't think these code size improvements are significant enough
to justify this change on its own (for me, the primary motivation is
reducing code complexity), but they I think are a nice side-effect.

Reviewers: rsmith, sammccall, ymandel, aaron.ballman

Reviewed By: rsmith, sammccall, ymandel, aaron.ballman

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82921
2020-07-06 13:38:01 +02:00
Dmitri Gribenko 8e750b1f0a Make RecursiveASTVisitor call WalkUpFrom for operators when the data recursion queue is absent
Reviewers: eduucaldas, ymandel, rsmith

Reviewed By: eduucaldas

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82889
2020-07-06 13:38:01 +02:00
Dmitri Gribenko c19c6b1722 Make RecursiveASTVisitor call WalkUpFrom for unary and binary operators in post-order traversal mode
Reviewers: ymandel, eduucaldas, rsmith

Reviewed By: eduucaldas, rsmith

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82787
2020-07-06 13:38:01 +02:00
Dmitri Gribenko 7349479f22 RecursiveASTVisitor: don't call WalkUp unnecessarily in post-order traversal
Summary:
How does RecursiveASTVisitor call the WalkUp callback for expressions?

* In pre-order traversal mode, RecursiveASTVisitor calls the WalkUp
  callback from the default implementation of Traverse callbacks.

* In post-order traversal mode when we don't have a DataRecursionQueue,
  RecursiveASTVisitor also calls the WalkUp callback from the default
  implementation of Traverse callbacks.

* However, in post-order traversal mode when we have a DataRecursionQueue,
  RecursiveASTVisitor calls the WalkUp callback from PostVisitStmt.

As a result, when the user overrides the Traverse callback, in pre-order
traversal mode they never get the corresponding WalkUp callback. However
in the post-order traversal mode the WalkUp callback is invoked or not
depending on whether the data recursion optimization could be applied.

I had to adjust the implementation of TraverseCXXForRangeStmt in the
syntax tree builder to call the WalkUp method directly, as it was
relying on this behavior. There is an existing test for this
functionality and it prompted me to make this extra fix.

In addition, I had to fix the default implementation implementation of
RecursiveASTVisitor::TraverseSynOrSemInitListExpr to call WalkUpFrom in
the same manner as the implementation generated by the DEF_TRAVERSE_STMT
macro. Without this fix, the InitListExprIsPostOrderNoQueueVisitedTwice
test was failing because WalkUpFromInitListExpr was never called.

Reviewers: eduucaldas, ymandel

Reviewed By: eduucaldas, ymandel

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82486
2020-07-06 13:38:01 +02:00
Dmitri Gribenko 19eaff650c Revert RecursiveASTVisitor fixes.
This reverts commit 8bf4c40af8.
This reverts commit 7b0be962d6.
This reverts commit 94454442c3.

Some compilers on some buildbots didn't accept the specialization of
is_same_method_impl in a non-namespace scope.
2020-07-03 13:48:24 +02:00
Dmitri Gribenko 8bf4c40af8 Make RecursiveASTVisitor call WalkUpFrom for operators when the data recursion queue is absent
Reviewers: eduucaldas, ymandel, rsmith

Reviewed By: eduucaldas

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82889
2020-07-03 13:03:19 +02:00
Dmitri Gribenko 7b0be962d6 Make RecursiveASTVisitor call WalkUpFrom for unary and binary operators in post-order traversal mode
Reviewers: ymandel, eduucaldas, rsmith

Reviewed By: eduucaldas, rsmith

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82787
2020-07-03 13:03:19 +02:00
Dmitri Gribenko 94454442c3 RecursiveASTVisitor: don't call WalkUp unnecessarily in post-order traversal
Summary:
How does RecursiveASTVisitor call the WalkUp callback for expressions?

* In pre-order traversal mode, RecursiveASTVisitor calls the WalkUp
  callback from the default implementation of Traverse callbacks.

* In post-order traversal mode when we don't have a DataRecursionQueue,
  RecursiveASTVisitor also calls the WalkUp callback from the default
  implementation of Traverse callbacks.

* However, in post-order traversal mode when we have a DataRecursionQueue,
  RecursiveASTVisitor calls the WalkUp callback from PostVisitStmt.

As a result, when the user overrides the Traverse callback, in pre-order
traversal mode they never get the corresponding WalkUp callback. However
in the post-order traversal mode the WalkUp callback is invoked or not
depending on whether the data recursion optimization could be applied.

I had to adjust the implementation of TraverseCXXForRangeStmt in the
syntax tree builder to call the WalkUp method directly, as it was
relying on this behavior. There is an existing test for this
functionality and it prompted me to make this extra fix.

In addition, I had to fix the default implementation implementation of
RecursiveASTVisitor::TraverseSynOrSemInitListExpr to call WalkUpFrom in
the same manner as the implementation generated by the DEF_TRAVERSE_STMT
macro. Without this fix, the InitListExprIsPostOrderNoQueueVisitedTwice
test was failing because WalkUpFromInitListExpr was never called.

Reviewers: eduucaldas, ymandel

Reviewed By: eduucaldas, ymandel

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82486
2020-07-03 13:03:19 +02:00
Dmitri Gribenko 7988969143 Added tests for RecursiveASTVisitor for AST nodes that are special cased
Summary:
RecursiveASTVisitor has special code for handling operator AST nodes,
specifically, unary, binary, and compound assignment operators. In this
change I'm adding tests for operator AST nodes that follow the existing
pattern of tests for the CallExpr node (an AST node that triggers the
common code path).

Reviewers: ymandel, eduucaldas

Reviewed By: ymandel, eduucaldas

Subscribers: gribozavr2, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82875
2020-07-03 13:03:18 +02:00
Dmitri Gribenko 8e5a56865f Add tests for sequences of callbacks that RecursiveASTVisitor produces
Summary:
These tests show a bug: post-order traversal introduces an extra call to
WalkUp*, that is not present in pre-order traversal. I'm fixing this bug
in a follow-up commit.

Reviewers: ymandel, eduucaldas

Reviewed By: ymandel, eduucaldas

Subscribers: gribozavr2, mgorny, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82485
2020-06-29 12:36:01 +02:00