[PATCH] lower-bitint: Fix up VIEW_CONVERT_EXPR handling [PR113408]

[Jakub Jelinek]

Hi!

Unlike NOP_EXPR/CONVERT_EXPR which are GIMPLE_UNARY_RHS, VIEW_CONVERT_EXPR
is GIMPLE_SINGLE_RHS and so gimple_assign_rhs1 contains the operand wrapped
in VIEW_CONVERT_EXPR tree.

So, to handle it like other casts we need to look through it.

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

2024-01-17  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/113408
        * gimple-lower-bitint.cc (bitint_large_huge::handle_stmt): For
        VIEW_CONVERT_EXPR, pass TREE_OPERAND (rhs1, 0) rather than rhs1
        to handle_cast.

        * gcc.dg/bitint-71.c: New test.

--- gcc/gimple-lower-bitint.cc.jj       2024-01-15 17:34:00.000000000 +0100
+++ gcc/gimple-lower-bitint.cc  2024-01-16 12:32:56.617721208 +0100
@@ -1975,9 +1975,12 @@ bitint_large_huge::handle_stmt (gimple *
        case INTEGER_CST:
          return handle_operand (gimple_assign_rhs1 (stmt), idx);
        CASE_CONVERT:
-       case VIEW_CONVERT_EXPR:
          return handle_cast (TREE_TYPE (gimple_assign_lhs (stmt)),
                              gimple_assign_rhs1 (stmt), idx);
+       case VIEW_CONVERT_EXPR:
+         return handle_cast (TREE_TYPE (gimple_assign_lhs (stmt)),
+                             TREE_OPERAND (gimple_assign_rhs1 (stmt), 0),
+                             idx);
        default:
          break;
        }
--- gcc/testsuite/gcc.dg/bitint-71.c.jj 2024-01-16 12:38:16.679239526 +0100
+++ gcc/testsuite/gcc.dg/bitint-71.c    2024-01-16 12:37:24.724967020 +0100
@@ -0,0 +1,18 @@
+/* PR tree-optimization/113408 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=c23 -O2" } */
+
+#if __BITINT_MAXWIDTH__ >= 713
+struct A { _BitInt(713) b; } g;
+#else
+struct A { _BitInt(49) b; } g;
+#endif
+int f;
+
+void
+foo (void)
+{
+  struct A j = g;
+  if (j.b)
+    f = 0;
+}

        Jakub