On Thu, Jan 18, 2024 at 01:34:53PM +0100, Richard Biener wrote:
> So - if we simply do
>
> /* If the input and output modes are both the same, we are done. */
> if (mode == GET_MODE (op0) || (mode == BLKmode && MEM_P (op0))
> ;
>
> ? After all if we want BLKmode we want a MEM, and if we have one
> we should be done already. V_C_E isn't supposed to do any value
> transform.
We'd need to make sure that op0 is actually MEM, which is not the case.
The following patch seems to work though, the discover_nonconstant_array_refs_r
part helps for -O2, the expr.cc part is needed at all optimization levels.
2024-01-18 Jakub Jelinek <ja...@redhat.com>
* 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>: If mode is
BLKmode and type a BITINT_TYPE from a non-BLKmode VAR_P with MEM
DECL_RTL, use adjust_address to BLKmode for it instead of expand_expr.
--- gcc/cfgexpand.cc.jj 2024-01-16 11:45:16.159326506 +0100
+++ gcc/cfgexpand.cc 2024-01-18 13:41:54.579551282 +0100
@@ -6380,11 +6380,16 @@ 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 BITINT_TYPEs. */
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
+ && TREE_CODE (TREE_TYPE (t)) == BITINT_TYPE
+ && 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 13:38:19.677556646 +0100
@@ -12382,6 +12382,17 @@ expand_expr_real_1 (tree exp, rtx target
}
}
+ /* Ensure non-BLKmode array VAR_DECLs VCEd to BLKmode BITINT_TYPE
+ aren't promoted to registers. */
+ if (op0 == NULL_RTX
+ && mode == BLKmode
+ && TREE_CODE (type) == BITINT_TYPE
+ && VAR_P (treeop0)
+ && DECL_MODE (treeop0) != BLKmode
+ && DECL_RTL_SET_P (treeop0)
+ && MEM_P (DECL_RTL (treeop0)))
+ op0 = adjust_address (DECL_RTL (treeop0), BLKmode, 0);
+
if (!op0)
op0 = expand_expr_real (treeop0, NULL_RTX, VOIDmode, modifier,
NULL, inner_reference_p);
Jakub
