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[committed] d: Fix callee destructor call invalidates the live object [PR113758]

Message ID 20240212161454.1200290-1-ibuclaw@gdcproject.org
State New
Headers show
Series [committed] d: Fix callee destructor call invalidates the live object [PR113758] | expand

Commit Message

Iain Buclaw Feb. 12, 2024, 4:14 p.m. UTC 
Hi,

This patch fixes code generation problem with passing objects by
invisible reference - because of a defined cpctor or dtor.

When generating the argument, check the isCalleeDestroyingArgs hook, and
force a TARGET_EXPR to be created if true, so that a reference to the
live object isn't passed directly to the function that runs dtors.

When instead dealing with caller running destructors, two temporaries
were being generated, one explicit temporary generated by the D
front-end, and another implicitly by the code generator.  This has been
reduced to one by setting DECL_VALUE_EXPR on the explicit temporary to
bind it to the implicit slot created for the TARGET_EXPR, as that has
the shorter lifetime of the two.

Bootstrapped and regression tested on x86_64-linux-gnu/-m32, committed
to mainline.

Regards,
Iain.

---
	PR d/113758

gcc/d/ChangeLog:

	* d-codegen.cc (d_build_call): Force a TARGET_EXPR when callee
	destorys its arguments.
	* decl.cc (DeclVisitor::visit (VarDeclaration *)): Set
	SET_DECL_VALUE_EXPR on the temporary variable to make it a placeholder
	for the TARGET_EXPR_SLOT.

gcc/testsuite/ChangeLog:

	* gdc.dg/torture/pr113758.d: New test.
---
 gcc/d/d-codegen.cc                      | 15 +++++++++++----
 gcc/d/decl.cc                           | 22 ++++++++++++++++++++--
 gcc/testsuite/gdc.dg/torture/pr113758.d | 19 +++++++++++++++++++
 3 files changed, 50 insertions(+), 6 deletions(-)
 create mode 100644 gcc/testsuite/gdc.dg/torture/pr113758.d
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Patch

diff --git a/gcc/d/d-codegen.cc b/gcc/d/d-codegen.cc
index 95dc8b6327e..dc528164aaf 100644
--- a/gcc/d/d-codegen.cc
+++ b/gcc/d/d-codegen.cc
@@ -2270,10 +2270,17 @@  d_build_call (TypeFunction *tf, tree callable, tree object,
 	      Type *t = arg->type->toBasetype ();
 	      StructDeclaration *sd = t->baseElemOf ()->isTypeStruct ()->sym;
 
-	      /* Nested structs also have ADDRESSABLE set, but if the type has
-		 neither a copy constructor nor a destructor available, then we
-		 need to take care of copying its value before passing it.  */
-	      if (arg->op == EXP::structLiteral || (!sd->postblit && !sd->dtor))
+	      /* Need to take care of copying its value before passing the
+		 argument in the following scenarios:
+		 - The argument is a literal expression; a CONSTRUCTOR can't
+		 have its address taken.
+		 - The type has neither a copy constructor nor a destructor
+		 available; nested structs also have ADDRESSABLE set.
+		 - The ABI of the function expects the callee to destroy its
+		 arguments; when the caller is handles destruction, then `targ'
+		 has already been made into a temporary. */
+	      if (arg->op == EXP::structLiteral || (!sd->postblit && !sd->dtor)
+		  || target.isCalleeDestroyingArgs (tf))
 		targ = force_target_expr (targ);
 
 	      targ = convert (build_reference_type (TREE_TYPE (targ)),
diff --git a/gcc/d/decl.cc b/gcc/d/decl.cc
index d2e84d3ba61..827495b3e30 100644
--- a/gcc/d/decl.cc
+++ b/gcc/d/decl.cc
@@ -863,10 +863,28 @@  public:
 	    /* Maybe put variable on list of things needing destruction.  */
 	    if (d->needsScopeDtor ())
 	      {
+		/* Rewrite: `decl = exp' => TARGET_EXPR(decl, exp, dtor).  */
 		vec_safe_push (d_function_chain->vars_in_scope, decl);
+
 		/* Force a TARGET_EXPR to add the corresponding cleanup.  */
-		exp = force_target_expr (compound_expr (exp, decl));
-		TARGET_EXPR_CLEANUP (exp) = build_expr (d->edtor);
+		if (TREE_CODE (exp) != TARGET_EXPR)
+		  {
+		    if (VOID_TYPE_P (TREE_TYPE (exp)))
+		      exp = compound_expr (exp, decl);
+
+		    exp = force_target_expr (exp);
+		  }
+
+		TARGET_EXPR_CLEANUP (exp)
+		  = compound_expr (TARGET_EXPR_CLEANUP (exp),
+				   build_expr (d->edtor));
+
+		/* The decl is really an alias for the TARGET_EXPR slot.  */
+		SET_DECL_VALUE_EXPR (decl, TARGET_EXPR_SLOT (exp));
+		DECL_HAS_VALUE_EXPR_P (decl) = 1;
+		/* This tells the gimplifier not to emit a clobber for the decl
+		   as its lifetime ends when the slot gets cleaned up.  */
+		TREE_ADDRESSABLE (decl) = 0;
 	      }
 
 	    add_stmt (exp);
diff --git a/gcc/testsuite/gdc.dg/torture/pr113758.d b/gcc/testsuite/gdc.dg/torture/pr113758.d
new file mode 100644
index 00000000000..dc53883a8de
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/pr113758.d
@@ -0,0 +1,19 @@ 
+// { dg-do run }
+// { dg-skip-if "needs gcc/config.d" { ! d_runtime } }
+struct S113758
+{
+    int field;
+    ~this() { field = 0; }
+}
+
+void main()
+{
+    auto var = S113758(1);
+    f113758d(var);
+    assert(var.field == 1);
+    f113758cxx(var);
+    assert(var.field == 1);
+}
+
+extern (D)   void f113758d(S113758 arg) { }
+extern (C++) void f113758cxx(S113758 arg) { }