http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54898
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-11
15:16:07 UTC ---
We produce this situation somewhen during WPA stage (probably type merging).
(gdb) p expr
$1 = (tree) 0x7ffff693e3f0
(gdb) p expr->type_common.main_variant
$2 = (tree) 0x7ffff6922b28
type merging assumes that if TYPE_MAIN_VARIANT (t) == t then t will
prevail or be replaced with a different type that also is a main variant.
we first read $2, with main variant 0x7ffff67f05e8:
(gdb) call debug_tree ($2)
<integer_type 0x7ffff6922b28 wchar_t SI
size <integer_cst 0x7ffff67f40a0 type <integer_type 0x7ffff67f00a8
bitsizetype> constant 32>
unit size <integer_cst 0x7ffff67f40c0 type <integer_type 0x7ffff67f0000
sizetype> constant 4>
align 32 symtab 0 alias set -1 structural equality precision 32 min
<integer_cst 0x7ffff67f4040 -2147483648> max <integer_cst 0x7ffff67f4060
2147483647> context <translation_unit_decl 0x7ffff67fbf18 D.2366>>
(gdb) call debug_tree ($10)
<integer_type 0x7ffff67f05e8 int public SI
size <integer_cst 0x7ffff67f40a0 type <integer_type 0x7ffff67f00a8
bitsizetype> constant 32>
unit size <integer_cst 0x7ffff67f40c0 type <integer_type 0x7ffff67f0000
sizetype> constant 4>
align 32 symtab 0 alias set -1 canonical type 0x7ffff67f05e8 precision 32
min <integer_cst 0x7ffff67f4040 -2147483648> max <integer_cst 0x7ffff67f4060
2147483647>
pointer_to_this <pointer_type 0x7ffff67f82a0>>
then we read $1
(gdb) call debug_tree ($1)
<integer_type 0x7ffff693e3f0 SI
size <integer_cst 0x7ffff67f40a0 type <integer_type 0x7ffff67f00a8
bitsizetype> constant 32>
unit size <integer_cst 0x7ffff67f40c0 type <integer_type 0x7ffff67f0000
sizetype> constant 4>
align 32 symtab 0 alias set -1 structural equality precision 32 min
<integer_cst 0x7ffff6912a20 -2147483648> max <integer_cst 0x7ffff6912a40
2147483647>>
(gdb) call debug_tree ($1->type_common.main_variant)
<integer_type 0x7ffff6922b28 wchar_t SI
size <integer_cst 0x7ffff67f40a0 type <integer_type 0x7ffff67f00a8
bitsizetype> constant 32>
unit size <integer_cst 0x7ffff67f40c0 type <integer_type 0x7ffff67f0000
sizetype> constant 4>
align 32 symtab 0 alias set -1 canonical type 0x7ffff67f05e8 precision 32
min <integer_cst 0x7ffff67f4040 -2147483648> max <integer_cst 0x7ffff67f4060
2147483647> context <translation_unit_decl 0x7ffff67fbf18 D.2366>
pointer_to_this <pointer_type 0x7ffff6922a80>>
ouch. With the following asserts the testcase can possibly be reduced:
Index: gcc/tree-streamer-in.c
===================================================================
--- gcc/tree-streamer-in.c (revision 192359)
+++ gcc/tree-streamer-in.c (working copy)
@@ -703,6 +703,7 @@ lto_input_ts_type_common_tree_pointers (
/* Do not stream TYPE_NEXT_VARIANT, we reconstruct the variant lists
during fixup. */
TYPE_MAIN_VARIANT (expr) = stream_read_tree (ib, data_in);
+ gcc_assert (TYPE_MAIN_VARIANT (expr) == TYPE_MAIN_VARIANT (TYPE_MAIN_VARIANT
(expr)) || TYPE_MAIN_VARIANT (TYPE_MAIN_VARIANT (expr)) == NULL_TREE);
TYPE_CONTEXT (expr) = stream_read_tree (ib, data_in);
/* TYPE_CANONICAL gets re-computed during type merging. */
TYPE_CANONICAL (expr) = NULL_TREE;
Index: gcc/tree-streamer-out.c
===================================================================
--- gcc/tree-streamer-out.c (revision 192359)
+++ gcc/tree-streamer-out.c (working copy)
@@ -612,6 +612,7 @@ write_ts_type_common_tree_pointers (stru
reconstructed during fixup. */
/* Do not stream TYPE_NEXT_VARIANT, we reconstruct the variant lists
during fixup. */
+ gcc_assert (TYPE_MAIN_VARIANT (expr) == TYPE_MAIN_VARIANT (TYPE_MAIN_VARIANT
(expr)));
stream_write_tree (ob, TYPE_MAIN_VARIANT (expr), ref_p);
stream_write_tree (ob, TYPE_CONTEXT (expr), ref_p);
/* TYPE_CANONICAL is re-computed during type merging, so no need
