2016-03-21 19:44:05 +08:00
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// RUN: %clang_cc1 -std=c++1y -triple i686-pc-windows-msvc -emit-llvm %s -o - | FileCheck %s
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[Cxx1z] Implement Lambda Capture of *this by Value as [=,*this] (P0018R3)
Implement lambda capture of *this by copy.
For e.g.:
struct A {
int d = 10;
auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; }
};
auto L = A{}.foo(); // A{}'s lifetime is gone.
// Below is still ok, because *this was captured by value.
assert(L(10) == 20);
assert(L(100) == 120);
If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined.
Implementation Strategy:
- amend the parser to accept *this in the lambda introducer
- add a new king of capture LCK_StarThis
- teach Sema::CheckCXXThisCapture to handle by copy captures of the
enclosing object (i.e. *this)
- when CheckCXXThisCapture does capture by copy, the corresponding
initializer expression for the closure's data member
direct-initializes it thus making a copy of '*this'.
- in codegen, when assigning to CXXThisValue, if *this was captured by
copy, make sure it points to the corresponding field member, and
not, unlike when captured by reference, what the field member points
to.
- mark feature as implemented in svn
Much gratitude to Richard Smith for his carefully illuminating reviews!
llvm-svn: 263921
2016-03-21 17:25:37 +08:00
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//CHECK: %[[A_LAMBDA:.*]] = type { %struct.A }
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//CHECK: %[[B_LAMBDA:.*]] = type { %struct.B* }
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struct A {
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double a = 111;
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auto foo() { return [*this] { return a; }; }
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};
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namespace ns1 {
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int X = A{}.foo()();
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} //end ns1
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//CHECK: @"\01?foo@A@@QAE?A?<auto>@@XZ"(%struct.A* %this, %class.anon* noalias sret %[[A_LAMBDA_RETVAL:.*]])
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// get the first object with the closure type, which is of type 'struct.A'
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2016-03-21 19:40:15 +08:00
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//CHECK: %[[I0:.+]] = getelementptr inbounds %[[A_LAMBDA]], %[[A_LAMBDA]]* %[[A_LAMBDA_RETVAL]], i32 0, i32 0
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//CHECK: %[[I1:.+]] = bitcast %struct.A* %[[I0]] to i8*
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//CHECK: %[[I2:.+]] = bitcast %struct.A* %this1 to i8*
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[Cxx1z] Implement Lambda Capture of *this by Value as [=,*this] (P0018R3)
Implement lambda capture of *this by copy.
For e.g.:
struct A {
int d = 10;
auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; }
};
auto L = A{}.foo(); // A{}'s lifetime is gone.
// Below is still ok, because *this was captured by value.
assert(L(10) == 20);
assert(L(100) == 120);
If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined.
Implementation Strategy:
- amend the parser to accept *this in the lambda introducer
- add a new king of capture LCK_StarThis
- teach Sema::CheckCXXThisCapture to handle by copy captures of the
enclosing object (i.e. *this)
- when CheckCXXThisCapture does capture by copy, the corresponding
initializer expression for the closure's data member
direct-initializes it thus making a copy of '*this'.
- in codegen, when assigning to CXXThisValue, if *this was captured by
copy, make sure it points to the corresponding field member, and
not, unlike when captured by reference, what the field member points
to.
- mark feature as implemented in svn
Much gratitude to Richard Smith for his carefully illuminating reviews!
llvm-svn: 263921
2016-03-21 17:25:37 +08:00
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// copy the contents ...
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2016-03-21 19:40:15 +08:00
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//CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %[[I1]], i8* %[[I2]], i32 8, i32 8, i1 false)
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[Cxx1z] Implement Lambda Capture of *this by Value as [=,*this] (P0018R3)
Implement lambda capture of *this by copy.
For e.g.:
struct A {
int d = 10;
auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; }
};
auto L = A{}.foo(); // A{}'s lifetime is gone.
// Below is still ok, because *this was captured by value.
assert(L(10) == 20);
assert(L(100) == 120);
If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined.
Implementation Strategy:
- amend the parser to accept *this in the lambda introducer
- add a new king of capture LCK_StarThis
- teach Sema::CheckCXXThisCapture to handle by copy captures of the
enclosing object (i.e. *this)
- when CheckCXXThisCapture does capture by copy, the corresponding
initializer expression for the closure's data member
direct-initializes it thus making a copy of '*this'.
- in codegen, when assigning to CXXThisValue, if *this was captured by
copy, make sure it points to the corresponding field member, and
not, unlike when captured by reference, what the field member points
to.
- mark feature as implemented in svn
Much gratitude to Richard Smith for his carefully illuminating reviews!
llvm-svn: 263921
2016-03-21 17:25:37 +08:00
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struct B {
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double b = 222;
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auto bar() { return [this] { return b; }; };
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};
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namespace ns2 {
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int X = B{}.bar()();
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}
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//CHECK: @"\01?bar@B@@QAE?A?<auto>@@XZ"(%struct.B* %this, %class.anon.0* noalias sret %agg.result)
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2016-03-21 19:40:15 +08:00
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//CHECK: %[[I20:.+]] = getelementptr inbounds %class.anon.0, %class.anon.0* %agg.result, i32 0, i32 0
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//CHECK: store %struct.B* %this1, %struct.B** %[[I20]], align 4
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