[gcc/devel/rust/master] Merge #1452

[Thomas Schwinge]

https://gcc.gnu.org/g:7027e5c21ae6b8cb1ea2222e55960f1587071d14

commit 7027e5c21ae6b8cb1ea2222e55960f1587071d14
Merge: 7c3766ccfce 71b5bc8705c
Author: bors[bot] <26634292+bors[bot]@users.noreply.github.com>
Date:   Wed Aug 10 10:35:07 2022 +0000

    Merge #1452
    
    1452: transmute: Fix behavior by always performing the raw copy r=CohenArthur a=CohenArthur
    
    This desugars calls to transmute the following way:
    
    `transmute::<T1, T2>(value)`
    
    ->
    
    `*((T2 *) &value)`
    
    This always ends up being optimized into a simple copy for small types
    and a memcpy for larger types.
    
    Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>

Diff:

 gcc/rust/backend/rust-compile-intrinsic.cc       | 36 ++++++------------------
 gcc/testsuite/rust/execute/torture/transmute1.rs | 23 +++++++++++++++
 2 files changed, 32 insertions(+), 27 deletions(-)

diff --cc gcc/rust/backend/rust-compile-intrinsic.cc
index a68ccc56a13,75e8c99158b..67e38c3261c
--- a/gcc/rust/backend/rust-compile-intrinsic.cc
+++ b/gcc/rust/backend/rust-compile-intrinsic.cc
@@@ -309,36 -381,24 +309,18 @@@ transmute_handler (Context *ctx, TyTy::
  		   (unsigned long) target_size);
      }
  
 -  tree enclosing_scope = NULL_TREE;
 -  Location start_location = Location ();
 -  Location end_location = Location ();
 -
 -  tree code_block = ctx->get_backend ()->block (fndecl, enclosing_scope, {},
 -						start_location, end_location);
 -  ctx->push_block (code_block);
 +  enter_intrinsic_block (ctx, fndecl);
  
    // BUILTIN transmute FN BODY BEGIN
-   tree result_type_tree = TREE_TYPE (DECL_RESULT (fndecl));
-   tree result_expr = error_mark_node;
-   if (AGGREGATE_TYPE_P (TREE_TYPE (convert_me_expr)))
-     {
-       // Return *(orig_type*)&decl.  */
-       // tree t = build_fold_addr_expr_loc (location.gcc_location (), this->t_);
-       // t = fold_build1_loc (location.gcc_location (), NOP_EXPR,
-       //       	       build_pointer_type (this->orig_type_), t);
-       // return build_fold_indirect_ref_loc (location.gcc_location (), t);
- 
-       // result_expr = fold_build1_loc (Location ().gcc_location (),
-       // CONVERT_EXPR,
-       //   			     result_type_tree, convert_me_expr);
- 
-       tree t = build_fold_addr_expr_loc (Location ().gcc_location (),
- 					 convert_me_expr);
-       t = fold_build1_loc (Location ().gcc_location (), NOP_EXPR,
- 			   build_pointer_type (target_type_expr), t);
-       result_expr
- 	= build_fold_indirect_ref_loc (Location ().gcc_location (), t);
-     }
-   else
-     {
-       result_expr = ctx->get_backend ()->convert_expression (result_type_tree,
- 							     convert_me_expr,
- 							     Location ());
-     }
+ 
+   // Return *((orig_type*)&decl)  */
+ 
+   tree t
+     = build_fold_addr_expr_loc (Location ().gcc_location (), convert_me_expr);
+   t = fold_build1_loc (Location ().gcc_location (), NOP_EXPR,
+ 		       build_pointer_type (target_type_expr), t);
+   tree result_expr
+     = build_fold_indirect_ref_loc (Location ().gcc_location (), t);
  
    auto return_statement
      = ctx->get_backend ()->return_statement (fndecl, {result_expr},