expr: Fix up store_expr into SUBREG_PROMOTED_* target [PR108264]

The following testcase ICEs on s390x-linux (e.g. with -march=z13).
The problem is that target is (subreg/s/u:SI (reg/v:DI 66 [ x+-4 ]) 4)
and we call convert_move from temp to the SUBREG_REG of that, expecting
to extend the value properly.  That works nicely if temp has some
scalar integer mode (or partial one), but ICEs when temp has V4QImode
on the assertion that from and to modes have the same bitsize.
store_expr generally allows say store from V4QI to SI target because
they have the same size and if temp is a CONST_INT, we already have code
to convert the constant properly, so the following patch just adds handling
of non-scalar integer modes by converting them to the mode of target
first before convert_move extends them.

2023-01-03  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/108264
	* expr.cc (store_expr): For stores into SUBREG_PROMOTED_* targets
	from source which doesn't have scalar integral mode first convert
	it to outer_mode.

	* gcc.dg/pr108264.c: New test.

1 files changed, 3 insertions, 0 deletions

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 372ad34..15be1c8 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -6226,6 +6226,9 @@ store_expr (tree exp, rtx target, int call_param_p,
 	  temp = convert_modes (inner_mode, outer_mode, temp,
 				SUBREG_PROMOTED_SIGN (target));
 	}
+      else if (!SCALAR_INT_MODE_P (GET_MODE (temp)))
+	temp = convert_modes (outer_mode, TYPE_MODE (TREE_TYPE (exp)),
+			      temp, SUBREG_PROMOTED_SIGN (target));
 
       convert_move (SUBREG_REG (target), temp,
 		    SUBREG_PROMOTED_SIGN (target));