Merge #1087

1087: Use loop to initialize repeat arrays r=philberty a=dafaust

This PR changes how we compile initializers for arrays of repeating elements. I use the same approach outlined in the comments of the linked issue, with some tweaks. It is very similar to how the D language front-end compiles, the new function `Gcc_backend::array_initializer` is heavily inspired by the D front-end's `build_array_set`

This fixes the issue where the compiler tries to allocate a vec containing all elements of the array to be constructed, and therefore explodes on huge constructions (e.g. `let x = [0u8; 4 * 1024 * 1024 * 1024 * 1024]`)

However, we can only initialize non-const arrays in this way. For arrays in const contexts we must initialize them at compile time, and therefore continue using the old method.

Fixes: #1068 


Co-authored-by: David Faust <david.faust@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/gcc/rust/rust-backend.h b/gcc/rust/rust-backend.h
index 6bfebe3..17b7bae 100644
--- a/gcc/rust/rust-backend.h
+++ b/gcc/rust/rust-backend.h
@@ -275,6 +275,10 @@ public:
 				const std::vector<tree> &vals, Location)
     = 0;
 
+  virtual tree array_initializer (tree, tree, tree, tree, tree, tree *,
+				  Location)
+    = 0;
+
   // Return an expression for ARRAY[INDEX] as an l-value.  ARRAY is a valid
   // fixed-length array, not a slice.
   virtual tree array_index_expression (tree array, tree index, Location) = 0;