Hi Ted,
I would like to add elidable CXXConstructExpr as block-expr. Since
expression
(CXXConstructExpr 0x3268658 <col:5, col:7> 'class A''void (const class A
&) throw()' elidable
converts an lvalue 'const class A &' to an rvalue 'class A'. This step
is useful during AST evaluation.
So is this patch ok?
Index: lib/Analysis/CFG.cpp
===================================================================
--- lib/Analysis/CFG.cpp (revision 147306)
+++ lib/Analysis/CFG.cpp (working copy)
@@ -2768,8 +2768,7 @@
CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C,
AddStmtChoice asc) {
autoCreateBlock();
- if (!C->isElidable() && asc.alwaysAdd(*this, C))
- appendStmt(Block, C);
+ appendStmt(Block, C);
return VisitChildren(C);
}
于 2012/1/4 9:40, Xu Zhongxing 写道:
> AST does have all these information in it. It's just the linearized CFG
> reverses the order in which we see the AST nodes.
>
> 于 2012/1/4 5:48, Ted Kremenek 写道:
>> Interesting. If the AST doesn't have enough information for the analyzer
>> (and other clients) to do a good job here, then I think it would be
>> reasonable to investigate pushing an AST-level change to fix the issue.
>>
>> On Dec 29, 2011, at 4:03 AM, Xu Zhongxing wrote:
>>
>>> I admit this is not a correct solution. If I set add CXXConstructExpr bit
>>> in the CFG::BuildOptions to false, there exist some cases CXXConstructExpr
>>> is not added as block-level expr, where it should.
>>>
>>> Linearizing the CFG is great idea. I already enjoy it very much.
>>>
>>> We need to provide more information to CXXConstructExpr: its destination
>>> object (a variable or a temporary object that should be conjured) and its
>>> kind (base,complete).
>>>
>>> For the destination object, we could always conjure a temporary object and
>>> use LazyCompoundVal to bind the real object being constructed when we later
>>> see it.
>>>
>>> 于 2011/12/29 13:59, Ted Kremenek 写道:
>>>> Hi Zhongxing,
>>>>
>>>> I don't understand how this is actually fixing (1) or (2). Can you
>>>> explain? We're moving to a place where we will likely linearize the
>>>> entire CFG (this is already the case for the static analyzer), so it would
>>>> be great to find a solution to (1) or (2) that doesn't depend on whether
>>>> or not CXXConstructExpr is a block-level expression.
>>>>
>>>> Thanks,
>>>> Ted
>>>>
>>>> On Dec 27, 2011, at 8:38 PM, Zhongxing Xu wrote:
>>>>
>>>>> Author: zhongxingxu
>>>>> Date: Tue Dec 27 22:38:46 2011
>>>>> New Revision: 147306
>>>>>
>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=147306&view=rev
>>>>> Log:
>>>>> Enable the user to control whether CXXConstructExpr will be added as a
>>>>> block-level expr. Currently CXXConstructExpr is always added as a
>>>>> block-level
>>>>> expr. This caused two problems for the analyzer (and potentially for the
>>>>> CFG-based codegen).
>>>>> 1. We have no way to know whether a ctor call is base or complete.
>>>>> 2. We have no way to know the destination object being contructed.
>>>>>
>>>>> Modified:
>>>>> cfe/trunk/lib/Analysis/CFG.cpp
>>>>>
>>>>> Modified: cfe/trunk/lib/Analysis/CFG.cpp
>>>>> URL:
>>>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=147306&r1=147305&r2=147306&view=diff
>>>>> ==============================================================================
>>>>> --- cfe/trunk/lib/Analysis/CFG.cpp (original)
>>>>> +++ cfe/trunk/lib/Analysis/CFG.cpp Tue Dec 27 22:38:46 2011
>>>>> @@ -2768,7 +2768,7 @@
>>>>> CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C,
>>>>> AddStmtChoice asc) {
>>>>> autoCreateBlock();
>>>>> - if (!C->isElidable())
>>>>> + if (!C->isElidable()&& asc.alwaysAdd(*this, C))
>>>>> appendStmt(Block, C);
>>>>>
>>>>> return VisitChildren(C);
>>>>>
>>>>>
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