Remove unnecessary inclusion of Sema.h

Let me tell you a tale...

Within some twisted maze of debug info I've ended up implementing an
insane man's Include What You Use device. When the debugger emits debug
info it really shouldn't, I find out why & then realize the code could
be improved too.

In this instance CIndexDiagnostics.cpp had a lot more debug info with
Clang than GCC. Upon inspection a major culprit was all the debug info
describing clang::Sema. This was emitted because clang::Sema is
befriended by DiagnosticEngine which was rightly required, but GCC
doesn't emit debug info for friends so it never emitted anything for
Clang. Clang does emit debug info for friends (will be fixed/changed to
reduce debug info size).

But why didn't Clang just emit a declaration of Sema if this entire TU
didn't require a definition?

1) Diagnostic.h did the right thing, only using a declaration of Sema
and not including Sema.h at all.
2) Some other dependency of CIndexDiagnostics.cpp didn't do the right
thing. ASTUnit.h, only needing a declaration, still included Sema.h
(hence this commit which removes that include and adds the necessary
includes to the cpp files that were relying on this)
3) -flimit-debug-info didn't save us because of
EnterExpressionEvaluationContext, defined inline in Sema.h which fires
the "requiresCompleteType" check/flag (since it uses nested types from
Sema and calls Sema member functions) and thus, if debug info is ever
emitted for the type, the whole type is emitted and not just a
declaration.

Improving -flimit-debug-info to account for this would be... hard.
Modifying the code so that's not 'required to be complete' might be
possible, but probably only by moving EnterExpressionEvaluationContext
either into Sema, or out of Sema.h. That might be a bit too much of a
contortion to be bothered with.

Also, this is only one of the cases where emitting debug info for
friends caused us to emit a lot more debug info (this change reduces
Clang's DWO size by 0.93%, dropping friends entirely reduces debug info
by 3.2%) - I haven't hunted down the other cases, but I assume they
might be similar (Sema or something like it). IWYU or a similar tool
might help us reduce build times a bit, but analyzing debug info to find
these differences isn't worthwhile. I'll take the 3.2% win, provide this
small improvement to the code itself, and move on.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@190715 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Frontend/ASTUnit.h b/include/clang/Frontend/ASTUnit.h
index 52f7f098d68a9b7a3e5c64b609ac567c719e87e7..166f1a26aed406219037f7bb15871dd05727ed53 100644 (file)
--- a/include/clang/Frontend/ASTUnit.h
+++ b/include/clang/Frontend/ASTUnit.h
@@ -25,7 +25,6 @@
 #include "clang/Lex/ModuleLoader.h"
 #include "clang/Lex/PreprocessingRecord.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
-#include "clang/Sema/Sema.h"
 #include "clang/Serialization/ASTBitCodes.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/OwningPtr.h"
@@ -44,6 +43,7 @@ namespace llvm {
 }
 
 namespace clang {
+class Sema;
 class ASTContext;
 class ASTReader;
 class CodeCompleteConsumer;

diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index 531adcdb50b1e5acf467ce633807ef4365c71770..e2641ccec4a7970142d0a9ea23dcab9b3e9357e1 100644 (file)
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -29,6 +29,7 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorOptions.h"
+#include "clang/Sema/Sema.h"
 #include "clang/Serialization/ASTReader.h"
 #include "clang/Serialization/ASTWriter.h"
 #include "llvm/ADT/ArrayRef.h"

diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 15e282882b9026df76a1377e385204e04c7cfd7e..0fc36b2f02c6fd53aad420d2db5d0e7b1085abbe 100644 (file)
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -23,6 +23,7 @@
 #include "CXType.h"
 #include "CursorVisitor.h"
 #include "SimpleFormatContext.h"
+#include "clang/AST/Attr.h"
 #include "clang/AST/StmtVisitor.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/Version.h"

diff --git a/tools/libclang/CIndexCodeCompletion.cpp b/tools/libclang/CIndexCodeCompletion.cpp
index 8face6580ac97779584fc7e1476a3d6b20fec79e..865bb585b54d060a8dcb51f9b99162a84594d719 100644 (file)
--- a/tools/libclang/CIndexCodeCompletion.cpp
+++ b/tools/libclang/CIndexCodeCompletion.cpp
@@ -27,6 +27,7 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
+#include "clang/Sema/Sema.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Atomic.h"

diff --git a/tools/libclang/CXComment.cpp b/tools/libclang/CXComment.cpp
index ad131a5221d5b40caacc26951bccb1d5e9d8e186..46588568dc6337056576de36a1f9c3339b7dd0ff 100644 (file)
--- a/tools/libclang/CXComment.cpp
+++ b/tools/libclang/CXComment.cpp
@@ -16,6 +16,7 @@
 #include "CXCursor.h"
 #include "CXString.h"
 #include "SimpleFormatContext.h"
+#include "clang/AST/Attr.h"
 #include "clang/AST/CommentCommandTraits.h"
 #include "clang/AST/CommentVisitor.h"
 #include "clang/AST/Decl.h"

diff --git a/tools/libclang/CXCursor.cpp b/tools/libclang/CXCursor.cpp
index df3950478799d7064961118aa47cbf162456717b..b80ea4ee4ff1f800a9226c121586af5b675a0db1 100644 (file)
--- a/tools/libclang/CXCursor.cpp
+++ b/tools/libclang/CXCursor.cpp
@@ -18,6 +18,7 @@
 #include "CXString.h"
 #include "CXType.h"
 #include "clang-c/Index.h"
+#include "clang/AST/Attr.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"

diff --git a/tools/libclang/IndexingContext.cpp b/tools/libclang/IndexingContext.cpp
index 53561764991865ed4edbd283648c7db1fc3cfc94..609d25b9ee7b58b1c68ac11839b0d7b8185a0d0d 100644 (file)
--- a/tools/libclang/IndexingContext.cpp
+++ b/tools/libclang/IndexingContext.cpp
@@ -10,6 +10,7 @@
 #include "IndexingContext.h"
 #include "CIndexDiagnostic.h"
 #include "CXTranslationUnit.h"
+#include "clang/AST/Attr.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/Frontend/ASTUnit.h"