llvm-project/clang/lib/CodeGen
Douglas Gregor 146b8e9a58 When performing a derived-to-base cast on the right-hand side of the
synthesized move assignment within an implicitly-defined move
assignment operator, be sure to treat the derived-to-base cast as an
xvalue (rather than an lvalue). Otherwise, we'll end up getting the
wrong constructor.

Optimize a direct call to a trivial move assignment operator to an
aggregate copy, as we do for trivial copy assignment operators, and
update the the assertion in CodeGenFunction::EmitAggregateCopy() to
cope with this optimization.

Fixes PR10860.

llvm-svn: 139143
2011-09-06 16:26:56 +00:00
..
ABIInfo.h clang side to match the LLVM IR type system rewrite patch. 2011-07-09 17:41:47 +00:00
BackendUtil.cpp [driver] Add -mglobal-merge/-mno-global-merge machine options to enable/disable merging of 2011-08-26 00:26:29 +00:00
CGBlocks.cpp switch clang to use the new-new way of creating llvm::StructType's. 2011-08-12 17:43:31 +00:00
CGBlocks.h de-constify llvm::Type, patch by David Blaikie! 2011-07-18 04:24:23 +00:00
CGBuilder.h Make CGBuilderTy a typedef again; its functionality has been rolled back 2010-07-06 18:43:48 +00:00
CGBuiltin.cpp Fix a handful of dead stores found by Clang's static analyzer. There's a bunch of others I haven't touched. 2011-08-17 21:04:19 +00:00
CGCXX.cpp Disable the optimization that skips emission of complete, non-virtual 2011-07-26 23:18:30 +00:00
CGCXXABI.cpp remove unneeded llvm:: namespace qualifiers on some core types now that LLVM.h imports 2011-07-23 10:55:15 +00:00
CGCXXABI.h clean up forward declarations of raw_ostream to use the new LLVM.h 2011-07-23 10:35:09 +00:00
CGCall.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGCall.h now that we have a centralized place to do so, add some using declarations for 2011-07-20 06:58:45 +00:00
CGClass.cpp Declare and define implicit move constructor and assignment operator. 2011-08-30 19:58:05 +00:00
CGCleanup.cpp Simplify EH control flow by observing that EH scopes form a simple 2011-08-11 02:22:43 +00:00
CGCleanup.h Simplify EH control flow by observing that EH scopes form a simple 2011-08-11 02:22:43 +00:00
CGDebugInfo.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGDebugInfo.h Use new DIBuilder::finalize() at the end to wrap up debug info encoding for a translation unit. 2011-08-15 23:01:55 +00:00
CGDecl.cpp Track whether an AggValueSlot is potentially aliased, and do not 2011-08-25 23:04:34 +00:00
CGDeclCXX.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGException.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGException.h now that we have a centralized place to do so, add some using declarations for 2011-07-20 06:58:45 +00:00
CGExpr.cpp Slight optimization enabled by the previous assert: 2011-08-26 21:08:13 +00:00
CGExprAgg.cpp When performing a derived-to-base cast on the right-hand side of the 2011-09-06 16:26:56 +00:00
CGExprCXX.cpp When performing a derived-to-base cast on the right-hand side of the 2011-09-06 16:26:56 +00:00
CGExprComplex.cpp blocks: Support capturing complex variable in block. 2011-09-02 21:33:44 +00:00
CGExprConstant.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGExprScalar.cpp Fix r137086 to actually work properly in general. PR10650. 2011-08-14 04:50:34 +00:00
CGObjC.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGObjCGNU.cpp switch clang to use the new-new way of creating llvm::StructType's. 2011-08-12 17:43:31 +00:00
CGObjCMac.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGObjCRuntime.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGObjCRuntime.h Support for catching objc pointer objects in c++ catch-statement 2011-06-23 19:00:08 +00:00
CGRTTI.cpp CodeGen: rename CodeGenModule::Runtime to ObjCRuntime 2011-07-27 20:29:46 +00:00
CGRecordLayout.h clean up forward declarations of raw_ostream to use the new LLVM.h 2011-07-23 10:35:09 +00:00
CGRecordLayoutBuilder.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGStmt.cpp Track whether an AggValueSlot is potentially aliased, and do not 2011-08-25 23:04:34 +00:00
CGTemporaries.cpp Generalize Cleanup::Emit's "isForEH" parameter into a set 2011-07-12 20:27:29 +00:00
CGVTT.cpp remove unneeded llvm:: namespace qualifiers on some core types now that LLVM.h imports 2011-07-23 10:55:15 +00:00
CGVTables.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CGVTables.h now that we have a centralized place to do so, add some using declarations for 2011-07-20 06:58:45 +00:00
CGValue.h What say we document some of these AggValueSlot flags a bit 2011-08-26 08:02:37 +00:00
CMakeLists.txt Wire up the -ftest-coverage and -fprofile-arcs flags to .gcno file emission (at 2011-04-21 23:44:07 +00:00
CodeGenAction.cpp remove unneeded llvm:: namespace qualifiers on some core types now that LLVM.h imports 2011-07-23 10:55:15 +00:00
CodeGenFunction.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CodeGenFunction.h Track whether an AggValueSlot is potentially aliased, and do not 2011-08-25 23:04:34 +00:00
CodeGenModule.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CodeGenModule.h Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CodeGenTBAA.cpp remove unneeded llvm:: namespace qualifiers on some core types now that LLVM.h imports 2011-07-23 10:55:15 +00:00
CodeGenTBAA.h now that we have a centralized place to do so, add some using declarations for 2011-07-20 06:58:45 +00:00
CodeGenTypes.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
CodeGenTypes.h now that we have a centralized place to do so, add some using declarations for 2011-07-20 06:58:45 +00:00
ItaniumCXXABI.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
Makefile BUILD_ARCHIVE is the default for libraries, no need to set it. 2010-07-18 00:14:47 +00:00
MicrosoftCXXABI.cpp remove unneeded llvm:: namespace qualifiers on some core types now that LLVM.h imports 2011-07-23 10:55:15 +00:00
ModuleBuilder.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
README.txt These IRgen improvements have been done. 2009-07-23 03:03:07 +00:00
TargetInfo.cpp Extend the ASTContext constructor to delay the initialization of 2011-09-02 00:18:52 +00:00
TargetInfo.h The size of struct UnwindException varies by platform with no 2011-08-30 01:42:09 +00:00

README.txt

IRgen optimization opportunities.

//===---------------------------------------------------------------------===//

The common pattern of
--
short x; // or char, etc
(x == 10)
--
generates an zext/sext of x which can easily be avoided.

//===---------------------------------------------------------------------===//

Bitfields accesses can be shifted to simplify masking and sign
extension. For example, if the bitfield width is 8 and it is
appropriately aligned then is is a lot shorter to just load the char
directly.

//===---------------------------------------------------------------------===//

It may be worth avoiding creation of alloca's for formal arguments
for the common situation where the argument is never written to or has
its address taken. The idea would be to begin generating code by using
the argument directly and if its address is taken or it is stored to
then generate the alloca and patch up the existing code.

In theory, the same optimization could be a win for block local
variables as long as the declaration dominates all statements in the
block.

NOTE: The main case we care about this for is for -O0 -g compile time
performance, and in that scenario we will need to emit the alloca
anyway currently to emit proper debug info. So this is blocked by
being able to emit debug information which refers to an LLVM
temporary, not an alloca.

//===---------------------------------------------------------------------===//

We should try and avoid generating basic blocks which only contain
jumps. At -O0, this penalizes us all the way from IRgen (malloc &
instruction overhead), all the way down through code generation and
assembly time.

On 176.gcc:expr.ll, it looks like over 12% of basic blocks are just
direct branches!

//===---------------------------------------------------------------------===//