Re: [PATCH] lower-bitint: Force some arrays corresponding to large/huge _BitInt SSA_NAMEs to BLKmode

[Jakub Jelinek <jakub@redhat.com>]

On Thu, Jan 18, 2024 at 02:13:55PM +0100, Jakub Jelinek wrote:
> The == BITINT_TYPE check is non-essential, was just trying to keep existing
> behavior otherwise.  I can certainly drop that.

So following then?

2024-01-18  Jakub Jelinek  <jakub@redhat.com>
	    Richard Biener  <rguenther@suse.de>

	* cfgexpand.cc (discover_nonconstant_array_refs_r): Force non-BLKmode
	VAR_DECLs referenced in BLKmode VIEW_CONVERT_EXPRs into memory.
	* expr.cc (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: Do nothing
	but adjust_address also for BLKmode mode and MEM op0.

--- gcc/cfgexpand.cc.jj	2024-01-16 11:45:16.159326506 +0100
+++ gcc/cfgexpand.cc	2024-01-18 14:15:54.853008586 +0100
@@ -6380,11 +6380,15 @@ discover_nonconstant_array_refs_r (tree
   /* References of size POLY_INT_CST to a fixed-size object must go
      through memory.  It's more efficient to force that here than
      to create temporary slots on the fly.
-     RTL expansion expectes TARGET_MEM_REF to always address actual memory.  */
+     RTL expansion expectes TARGET_MEM_REF to always address actual memory.
+     Also, force to stack non-BLKmode vars accessed through VIEW_CONVERT_EXPR
+     to BLKmode type.  */
   else if (TREE_CODE (t) == TARGET_MEM_REF
 	   || (TREE_CODE (t) == MEM_REF
 	       && TYPE_SIZE (TREE_TYPE (t))
-	       && POLY_INT_CST_P (TYPE_SIZE (TREE_TYPE (t)))))
+	       && POLY_INT_CST_P (TYPE_SIZE (TREE_TYPE (t))))
+	   || (TREE_CODE (t) == VIEW_CONVERT_EXPR
+	       && TYPE_MODE (TREE_TYPE (t)) == BLKmode))
     {
       tree base = get_base_address (t);
       if (base
--- gcc/expr.cc.jj	2024-01-12 10:07:58.194851657 +0100
+++ gcc/expr.cc	2024-01-18 14:15:31.970328685 +0100
@@ -12389,6 +12389,10 @@ expand_expr_real_1 (tree exp, rtx target
       /* If the input and output modes are both the same, we are done.  */
       if (mode == GET_MODE (op0))
 	;
+      /* Similarly if the output mode is BLKmode and input is a MEM,
+	 adjust_address done below is all we need.  */
+      else if (mode == BLKmode && MEM_P (op0))
+	;
       /* If neither mode is BLKmode, and both modes are the same size
 	 then we can use gen_lowpart.  */
       else if (mode != BLKmode


	Jakub