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expansion: Fix ICEs with BLKmode VIEW_CONVERT_EXPR around non-BLKmode VAR_DECLs

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On aarch64 the backend decides to use non-BLKmode for some arrays
like unsigned long[4] - OImode in that case, but the corresponding
BITINT_TYPEs have BLKmode (like structures containing that many limb
elements).
This later causes ICEs durring expansion when expanding VIEW_CONVERT_EXPR
from non-BLKmode VAR_DECL to BLKmode BITINT_TYPE.

The following fix contains two parts, the discover_nonconstant_array_refs_r
is make sure we force such variables into memory and the expand_expr_real_1
change makes sure we don't try to extract a bitfield or something similar
which doesn't really work for BLKmode - as op0 is a MEM, all we need is
the op0 = adjust_address (op0, mode, 0); at the end to change the MEM's mode
to BLKmode.

2024-01-19  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.
This commit is contained in:
Jakub Jelinek 2024-01-19 09:31:42 +01:00
parent 730a801f95
commit 56778b69ce
2 changed files with 10 additions and 2 deletions
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8
gcc/cfgexpand.cc
View file

@ -6380,11 +6380,15 @@ discover_nonconstant_array_refs_r (tree * tp, int *walk_subtrees,
/* 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

4
gcc/expr.cc
View file

@ -12389,6 +12389,10 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
/* 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