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llvm-project/clang/test/CodeGenCXX/copy-initialization.cpp

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Rework our handling of copy construction of temporaries, which was a poor (and wrong) approximation of the actual rules governing when to build a copy and when it can be elided. The correct implementation is actually simpler than the approximation. When we only enumerate constructors as part of initialization (e.g., for direct initialization or when we're copying from a class type or one of its derived classes), we don't create a copy. When we enumerate all conversion functions, we do create a copy. Before, we created some extra copies and missed some others. The new test copy-initialization.cpp shows a case where we missed creating a (required, non-elidable) copy as part of a user-defined conversion, which resulted in a miscompile. This commit also fixes PR6757, where the missing copy made us reject well-formed code in the ternary operator. This commit also cleans up our handling of copy elision in the case where we create an extra copy of a temporary object, which became necessary now that we produce the right copies. The code that seeks to find the temporary object being copied has moved into Expr::getTemporaryObject(); it used to have two different not-quite-the-same implementations, one in Sema and one in CodeGen. Note that we still do not attempt to perform the named return value optimization, so we miss copy elisions for return values and throw expressions. llvm-svn: 100196
2010-04-03 02:24:57 +08:00
// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s | FileCheck %s
struct Foo {
Foo();
Foo(const Foo&);
};
struct Bar {
Bar();
operator const Foo&() const;
};
void f(Foo);
[test] Add {{.*}} to make tests immune to dso_local/dso_preemptable/(none) differences For a definition (of most linkage types), dso_local is set for ELF -fno-pic/-fpie and COFF, but not for Mach-O. This nuance causes unneeded binary format differences. This patch replaces (function) `define ` with `define{{.*}} `, (variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} ` if there is an explicit linkage. * Clang will set dso_local for Mach-O, which is currently implied by TargetMachine.cpp. This will make COFF/Mach-O and executable ELF similar. * Eventually I hope we can make dso_local the textual LLVM IR default (write explicit "dso_preemptable" when applicable) and -fpic ELF will be similar to everything else. This patch helps move toward that goal.
2020-12-31 12:45:56 +08:00
// CHECK-LABEL: define{{.*}} void @_Z1g3Foo(%struct.Foo* %foo)
Rework our handling of copy construction of temporaries, which was a poor (and wrong) approximation of the actual rules governing when to build a copy and when it can be elided. The correct implementation is actually simpler than the approximation. When we only enumerate constructors as part of initialization (e.g., for direct initialization or when we're copying from a class type or one of its derived classes), we don't create a copy. When we enumerate all conversion functions, we do create a copy. Before, we created some extra copies and missed some others. The new test copy-initialization.cpp shows a case where we missed creating a (required, non-elidable) copy as part of a user-defined conversion, which resulted in a miscompile. This commit also fixes PR6757, where the missing copy made us reject well-formed code in the ternary operator. This commit also cleans up our handling of copy elision in the case where we create an extra copy of a temporary object, which became necessary now that we produce the right copies. The code that seeks to find the temporary object being copied has moved into Expr::getTemporaryObject(); it used to have two different not-quite-the-same implementations, one in Sema and one in CodeGen. Note that we still do not attempt to perform the named return value optimization, so we miss copy elisions for return values and throw expressions. llvm-svn: 100196
2010-04-03 02:24:57 +08:00
void g(Foo foo) {
// CHECK: call void @_ZN3BarC1Ev
// CHECK: @_ZNK3BarcvRK3FooEv
// CHECK: call void @_Z1f3Foo
f(Bar());
// CHECK: call void @_ZN3FooC1Ev
// CHECK: call void @_Z1f3Foo
f(Foo());
// CHECK: call void @_ZN3FooC1ERKS_
// CHECK: call void @_Z1f3Foo
f(foo);
// CHECK: ret
}