Merge #725

725: Add array constant folding r=philberty a=rodrigovalle

Fixes #681 

I created a new ConstFoldArrayElems folder to visit ArrayElemsCopied and ArrayElemsValues while holding onto the original ArrayExpr object that we recurse into.

Co-authored-by: Rodrigo Valle <[email protected]>

Author: bors[bot]

gcc/rust/typecheck/rust-hir-const-fold.cc

@@ -70,5 +70,39 @@ ConstFoldItem::visit (HIR::ConstantItem &item)
   folded = folded_expr;
 }
 
+void
+ConstFoldArrayElems::visit (HIR::ArrayElemsValues &elems)
+{
+  unsigned long index = 0;
+  std::vector<unsigned long> indices;
+  std::vector<Bexpression *> values;
+
+  TyTy::BaseType *tyty = nullptr;
+  if (!tyctx->lookup_type (expr.get_mappings ().get_hirid (), &tyty))
+    {
+      rust_fatal_error (expr.get_locus (),
+			"did not resolve type for array elems values");
+      return;
+    }
+
+  Btype *btype = ConstFoldType::fold (tyty, ctx->get_backend ());
+
+  for (auto &value : elems.get_values ())
+    {
+      indices.push_back (index++);
+      values.push_back (ConstFoldExpr::fold (value.get ()));
+    }
+
+  folded
+    = ctx->get_backend ()->array_constructor_expression (btype, indices, values,
+							 expr.get_locus ());
+}
+
+void
+ConstFoldArrayElems::visit (HIR::ArrayElemsCopied &elems)
+{
+  // TODO
+}
+
 } // namespace ConstFold
 } // namespace Rust

gcc/rust/typecheck/rust-hir-const-fold.h

@@ -41,7 +41,11 @@ class ConstFoldType : public TyTy::TyVisitor
 
   void visit (TyTy::ADTType &) override { gcc_unreachable (); }
 
-  void visit (TyTy::ArrayType &) override { gcc_unreachable (); }
+  void visit (TyTy::ArrayType &type) override
+  {
+    Btype *element_ty = ConstFoldType::fold (type.get_element_type (), backend);
+    translated = backend->array_type (element_ty, type.get_capacity ());
+  }
 
   void visit (TyTy::ReferenceType &) override { gcc_unreachable (); }
 
@@ -233,6 +237,32 @@ class ConstFoldItem : public ConstFoldBase
   Bexpression *folded;
 };
 
+class ConstFoldArrayElems : public ConstFoldBase
+{
+  using ConstFoldBase::visit;
+
+public:
+  static Bexpression *fold (HIR::ArrayExpr &expr)
+  {
+    ConstFoldArrayElems folder (expr);
+    HIR::ArrayElems *elems = expr.get_internal_elements ();
+    elems->accept_vis (folder);
+    return folder.folded;
+  }
+
+  void visit (HIR::ArrayElemsValues &elems) override;
+  void visit (HIR::ArrayElemsCopied &elems) override;
+
+private:
+  ConstFoldArrayElems (HIR::ArrayExpr &expr)
+    : ConstFoldBase (), folded (ctx->get_backend ()->error_expression ()),
+      expr (expr)
+  {}
+
+  Bexpression *folded;
+  HIR::ArrayExpr &expr;
+};
+
 class ConstFoldExpr : public ConstFoldBase
 {
   using ConstFoldBase::visit;
@@ -361,6 +391,11 @@ class ConstFoldExpr : public ConstFoldBase
     gcc_unreachable ();
   }
 
+  void visit (HIR::ArrayExpr &expr) override
+  {
+    folded = ConstFoldArrayElems::fold (expr);
+  }
+
   void visit (HIR::ArithmeticOrLogicalExpr &expr) override
   {
     auto lhs = ConstFoldExpr::fold (expr.get_lhs ());

gcc/testsuite/rust/compile/torture/.traits3.rs.swp

@@ -0,0 +1,2 @@
+const TEST: [i32; 16] = [2, 6, 3, 10, 7, 0, 4, 13, 1, 11, 12, 5, 9, 14, 15, 8];
+// { dg-warning "unused name" "" { target *-*-* } .-1 }