Richard, I don't think this is possible. If we storing
VariableLengthArray* on FieldDecl, then in Lambda operator we can
access VariableLengthArray->getSizeExpr(). But! We won't be able to get
the llvm::Value* for this VariableLengthArray->getSizeExpr(),
calculated in another function. We should pass this llvm::Value* as a
member of RecordDecl for LambdaExpr! Here is a scheme:
foo() {
int vla[n+m];
....
some_lambda {vla....;}
....
}
What we have in CodeGen for this example:
CodeGenFunction(foo), llvm::DenseMap<const Expr*, llvm::Value*>
VLASizeMap[n+m]=value; VLASizeMap stores pre-calculated size of each
VLA.
{
FD->field_for_m+n_expr = (int [n+m]*)0;
CodeGenFunction CGF(some_lambda.operator(), FD);
}
CodeGenFunction(some_lambda.operator()), llvm::DenseMap<const Expr*,
llvm::Value*> VLASizeMap[n+m]=????? - llvm::Value* for 'n+m' is not
captured here, we don't have an access to 'value', calculated in
CodeGenFunction(foo) for expression 'n+m'.
To solve this problem we can try to capture 2 fields instead - one for
VariableLengthArray*, and another one for llvm::Value* calculated for
VariableLengthArray->getSizeExpr().
Best regards,
Alexey Bataev
=============
Software Engineer
Intel Compiler Team
22 Июль 2014 г. 8:57:54, Richard Smith писал:
On Mon, Jul 21, 2014 at 5:43 AM, Alexey Bataev <[email protected]
<mailto:[email protected]>> wrote:
Updated version after last review. Unfortunately, I don't think it
is possible to pass captured expression as a VariableLengthArray
*. I have to capture expr of VariableLengthArray * and then cast
it to SizeExpr->getType() type to make lambda capture this type,
not VariableLengthArray *. I have to pass actual value of SizeExpr
to the Lambda in this field, because it is defined only in calling
function and in Lambda it can be received only in one of captured
fields.
I don't understand what you're saying. What I'm suggesting is storing
the VariableLengthArray* in the InitializerOrBitWidth field on
FieldDecl, instead of storing the array bound there.
http://reviews.llvm.org/D4368
Files:
include/clang/AST/Decl.h
include/clang/AST/LambdaCapture.h
include/clang/Basic/DiagnosticSemaKinds.td
lib/AST/Decl.cpp
lib/AST/Expr.cpp
lib/AST/ExprCXX.cpp
lib/AST/StmtPrinter.cpp
lib/AST/StmtProfile.cpp
lib/CodeGen/CGDebugInfo.cpp
lib/CodeGen/CGExprCXX.cpp
lib/CodeGen/CodeGenFunction.cpp
lib/Sema/SemaDecl.cpp
lib/Sema/SemaExpr.cpp
lib/Sema/TreeTransform.h
test/CodeGenCXX/instantiate-typeof-vla.cpp
test/SemaTemplate/instantiate-typeof.cpp
tools/libclang/IndexBody.cpp
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