[PATCH] middle-end/103038 - avoid ICE with -ftrivial-auto-var-init=pattern

[Richard Biener via Gcc-patches]

This avoids ICEing with expanding a VIEW_CONVERT_EXRP of a SSA name
on the LHS by making sure we can native-interpret OFFSET_TYPE and
by never building such a LHS but instead view-converting the RHS
for SSA LHS.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

2021-11-02  Richard Biener  <rguent...@suse.de>

        PR middle-end/103038
        * fold-const.c (native_interpret_expr): Handle OFFSET_TYPE.
        (can_native_interpret_type_p): Likewise.
        * internal-fn.c (expand_DEFERRED_INIT): View-convert the
        RHS if the LHS is an SSA name.

        * g++.dg/pr103038.C: New testcase.
---
 gcc/fold-const.c                | 2 ++
 gcc/internal-fn.c               | 8 ++++++--
 gcc/testsuite/g++.dg/pr103038.C | 5 +++++
 3 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/pr103038.C

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 54f91f0149c..2d3ba07e541 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8791,6 +8791,7 @@ native_interpret_expr (tree type, const unsigned char 
*ptr, int len)
     case BOOLEAN_TYPE:
     case POINTER_TYPE:
     case REFERENCE_TYPE:
+    case OFFSET_TYPE:
       return native_interpret_int (type, ptr, len);
 
     case REAL_TYPE:
@@ -8827,6 +8828,7 @@ can_native_interpret_type_p (tree type)
     case REAL_TYPE:
     case COMPLEX_TYPE:
     case VECTOR_TYPE:
+    case OFFSET_TYPE:
       return true;
     default:
       return false;
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 9e10da0ad5c..fd6cb0995d9 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3090,8 +3090,12 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
                             (total_bytes * BITS_PER_UNIT, 1);
              wide_int w = wi::from_buffer (buf, total_bytes);
              init = wide_int_to_tree (itype, w);
-             /* Pun the LHS to make sure its type has constant size.  */
-             lhs = build1 (VIEW_CONVERT_EXPR, itype, lhs);
+             /* Pun the LHS to make sure its type has constant size
+                unless it is an SSA name where that's already known.  */
+             if (TREE_CODE (lhs) != SSA_NAME)
+               lhs = build1 (VIEW_CONVERT_EXPR, itype, lhs);
+             else
+               init = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), init);
            }
        }
       else
diff --git a/gcc/testsuite/g++.dg/pr103038.C b/gcc/testsuite/g++.dg/pr103038.C
new file mode 100644
index 00000000000..bb7183a460e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr103038.C
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-ftrivial-auto-var-init=pattern" } */
+
+struct S;
+void test() { int(S::*PtrMem); }
-- 
2.31.1