Hi,
RVO was already being done when returning a constructor call via a
temporary, which in the front-end AST looks like:
return S.this((__tmp = {}, &__tmp), args...);
But this was not being done for copy construction calls, which instead
looks like:
return __copytmp = {}, S.this(&__copytmp, V(1).s), __copytmp;
This pattern is now matched and the temporary gets set up as a
DECL_VALUE_EXPR of the RESULT_DECL.
Regstrapped on x86_64-linux-gnu, committed to mainline, and backported
to releases/gcc-13, gcc-14, and gcc-15.
Regards,
Iain.
---
PR d/123422
gcc/d/ChangeLog:
* expr.cc (ExprVisitor::visit (ArrayLiteralExp *)): Don't add
TARGET_EXPR around constructor.
* toir.cc (IRVisitor::visit (ReturnStatement *)): Recognize more
patterns for return value optimization.
gcc/testsuite/ChangeLog:
* gdc.dg/torture/pr123422.d: New test.
---
gcc/d/expr.cc | 2 +-
gcc/d/toir.cc | 57 +++++++++++++++++--------
gcc/testsuite/gdc.dg/torture/pr123422.d | 25 +++++++++++
3 files changed, 66 insertions(+), 18 deletions(-)
create mode 100644 gcc/testsuite/gdc.dg/torture/pr123422.d
diff --git a/gcc/d/expr.cc b/gcc/d/expr.cc
index bc1f788d022..79d1839f0d6 100644
--- a/gcc/d/expr.cc
+++ b/gcc/d/expr.cc
@@ -2675,7 +2675,7 @@ public:
gcc_assert (tb->ty == TY::Tarray);
ctor = force_target_expr (ctor);
ctor = d_array_value (type, size_int (e->elements->length),
- build_address (force_target_expr (ctor)));
+ build_address (ctor));
this->result_ = compound_expr (saved_elems, ctor);
}
else
diff --git a/gcc/d/toir.cc b/gcc/d/toir.cc
index a58b5963c02..462977f8173 100644
--- a/gcc/d/toir.cc
+++ b/gcc/d/toir.cc
@@ -1022,41 +1022,64 @@ public:
/* Detect a call to a constructor function, or if returning a struct
literal, write result directly into the return value. */
StructLiteralExp *sle = NULL;
+ DeclarationExp *de = NULL;
+ VarExp *ve = NULL;
bool using_rvo_p = false;
if (DotVarExp *dve = (s->exp->isCallExp ()
? s->exp->isCallExp ()->e1->isDotVarExp ()
: NULL))
{
+ /* Look for `var.__ctor(copytmp = {}, ©tmp)' */
if (dve->var->isCtorDeclaration ())
{
if (CommaExp *ce = dve->e1->isCommaExp ())
{
- /* Temporary initialized inside a return expression, and
- used as the return value. Replace it with the hidden
- reference to allow RVO return. */
- DeclarationExp *de = ce->e1->isDeclarationExp ();
- VarExp *ve = ce->e2->isVarExp ();
- if (de != NULL && ve != NULL
- && ve->var == de->declaration
- && ve->var->storage_class & STCtemp)
- {
- tree var = get_symbol_decl (ve->var);
- TREE_ADDRESSABLE (var) = 1;
- SET_DECL_VALUE_EXPR (var, decl);
- DECL_HAS_VALUE_EXPR_P (var) = 1;
- SET_DECL_LANG_NRVO (var, this->func_->shidden);
- using_rvo_p = true;
- }
+ de = ce->e1->isDeclarationExp ();
+ ve = ce->e2->isVarExp ();
}
else
sle = dve->e1->isStructLiteralExp ();
}
}
+ else if (CommaExp *ce1 = s->exp->isCommaExp ())
+ {
+ /* Look for `copytmp = {}, copytmp.__ctor(), copytmp' */
+ if (CommaExp *ce2 = ce1->e2->isCommaExp ())
+ {
+ DotVarExp *dve = ce2->e1->isCallExp ()
+ ? ce2->e1->isCallExp ()->e1->isDotVarExp () : NULL;
+
+ if (dve && dve->var->isCtorDeclaration ())
+ {
+ de = ce1->e1->isDeclarationExp ();
+ ve = ce2->e2->isVarExp ();
+ }
+ }
+ else
+ {
+ de = ce1->e1->isDeclarationExp ();
+ ve = ce1->e2->isVarExp ();
+ }
+ }
else
sle = s->exp->isStructLiteralExp ();
- if (sle != NULL)
+ if (de != NULL && ve != NULL
+ && ve->var == de->declaration
+ && ve->var->storage_class & STCtemp)
+ {
+ /* Temporary initialized inside a return expression, and
+ used as the return value. Replace it with the hidden
+ reference to allow RVO return. */
+ tree var = get_symbol_decl (ve->var);
+ TREE_ADDRESSABLE (var) = 1;
+ SET_DECL_VALUE_EXPR (var, decl);
+ DECL_HAS_VALUE_EXPR_P (var) = 1;
+ SET_DECL_LANG_NRVO (var, this->func_->shidden);
+ using_rvo_p = true;
+ }
+ else if (sle != NULL)
{
sle->sym = build_address (this->func_->shidden);
using_rvo_p = true;
diff --git a/gcc/testsuite/gdc.dg/torture/pr123422.d
b/gcc/testsuite/gdc.dg/torture/pr123422.d
new file mode 100644
index 00000000000..468a953af9b
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/pr123422.d
@@ -0,0 +1,25 @@
+// { dg-do run }
+// { dg-skip-if "needs gcc/config.d" { ! d_runtime } }
+struct S123422
+{
+ S123422* ptr;
+ this(int) { ptr = &this; }
+ this(ref inout S123422) { ptr = &this; }
+}
+
+struct V123422
+{
+ S123422 s;
+ this(int) { s = S123422(1); }
+}
+
+S123422 foo()
+{
+ return V123422(1).s;
+}
+
+void main()
+{
+ S123422 s = foo();
+ assert(&s == s.ptr);
+}
--
2.43.0
