[PATCH] expand: Fix up ICE on VCE from _Complex types to _BitInt [PR117458]

[Jakub Jelinek]

Hi!

extract_bit_field can't handle extraction of non-mode precision
from complex mode operands which don't live in memory, e.g. gen_lowpart
crashes on those.
The following patch in that case defers the extract_bit_field call
until op0 is forced into memory.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2024-11-19  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/117458
        * expr.cc (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: Don't
        call extract_bit_field if op0 has complex mode and isn't a MEM,
        instead first force op0 into memory and then call extract_bit_field.

        * gcc.dg/bitint-116.c: New test.

--- gcc/expr.cc.jj      2024-11-08 12:38:10.684495739 +0100
+++ gcc/expr.cc 2024-11-18 18:35:47.259349847 +0100
@@ -12505,7 +12505,9 @@ expand_expr_real_1 (tree exp, rtx target
        op0 = convert_modes (mode, GET_MODE (op0), op0,
                             TYPE_UNSIGNED (TREE_TYPE (treeop0)));
       /* If the output type is a bit-field type, do an extraction.  */
-      else if (reduce_bit_field && mode != BLKmode)
+      else if (reduce_bit_field
+              && mode != BLKmode
+              && (MEM_P (op0) || !COMPLEX_MODE_P (GET_MODE (op0))))
        return extract_bit_field (op0, TYPE_PRECISION (type), 0,
                                  TYPE_UNSIGNED (type), NULL_RTX,
                                  mode, mode, false, NULL);
@@ -12529,6 +12531,11 @@ expand_expr_real_1 (tree exp, rtx target
 
          emit_move_insn (target, op0);
          op0 = target;
+
+         if (reduce_bit_field && mode != BLKmode)
+           return extract_bit_field (op0, TYPE_PRECISION (type), 0,
+                                     TYPE_UNSIGNED (type), NULL_RTX,
+                                     mode, mode, false, NULL);
        }
 
       /* If OP0 is (now) a MEM, we need to deal with alignment issues.  If the
--- gcc/testsuite/gcc.dg/bitint-116.c.jj        2024-11-18 18:50:05.322348174 
+0100
+++ gcc/testsuite/gcc.dg/bitint-116.c   2024-11-18 18:50:57.785614318 +0100
@@ -0,0 +1,11 @@
+/* PR middle-end/117458 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=c23 -O2" } */
+
+typedef _BitInt(33) B __attribute__((may_alias));
+
+_BitInt(33)
+foo (_Complex float x)
+{
+  return *(B *)&x;
+}

        Jakub