[gcc r14-8184] lower-bitint: Fix up VIEW_CONVERT_EXPR handling [PR113408]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:2fb78d431ff3c05997ef31837d6eb319d84a4239

commit r14-8184-g2fb78d431ff3c05997ef31837d6eb319d84a4239
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Jan 17 13:55:50 2024 +0100

    lower-bitint: Fix up VIEW_CONVERT_EXPR handling [PR113408]
    
    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.
    
    2024-01-17  Jakub Jelinek  <jakub@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.

Diff:
---
 gcc/gimple-lower-bitint.cc       |  5 ++++-
 gcc/testsuite/gcc.dg/bitint-71.c | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc
index 672a9a33751..d3d113578d9 100644
--- a/gcc/gimple-lower-bitint.cc
+++ b/gcc/gimple-lower-bitint.cc
@@ -1975,9 +1975,12 @@ bitint_large_huge::handle_stmt (gimple *stmt, tree idx)
 	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;
 	}
diff --git a/gcc/testsuite/gcc.dg/bitint-71.c b/gcc/testsuite/gcc.dg/bitint-71.c
new file mode 100644
index 00000000000..f7ff8716f36
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-71.c
@@ -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;
+}