On Thu, Sep 10, 2020 at 04:09:24PM +0200, Richard Biener wrote:
> So we're usually streaming the bits and the tree portion of SCCs
> separately so I really wonder how we can end up with recursion here?
> For stmts they should only refer to BLOCKs also in the BLOCK tree
> which is streamed in before we stream in the stmts(?).
>
> So - isn't this an undetected stmt/tree references BLOCK not in
> BLOCK tree bug? See verify_location which might or might not
> handle all locations "correctly" though it looks like it obviously
> verifies all stmts locations this way. So the question is whether
> the function would pass verification at stream-out time ...
Looking at that align-3.C testcase on the trunk, I also see the recursive
lto_output_location_1 calls as well. First on block:
$18 = <block 0x7fffea738480>
which is in the block tree from what I can see just fine (see the end of
mail).
Now, output_function has code that should stream the BLOCK tree leafs:
/* Output DECL_INITIAL for the function, which contains the tree of
lexical scopes. */
stream_write_tree (ob, DECL_INITIAL (function), true);
/* As we do not recurse into BLOCK_SUBBLOCKS but only BLOCK_SUPERCONTEXT
collect block tree leafs and stream those. */
auto_vec<tree> block_tree_leafs;
if (DECL_INITIAL (function))
collect_block_tree_leafs (DECL_INITIAL (function), block_tree_leafs);
streamer_write_uhwi (ob, block_tree_leafs.length ());
for (unsigned i = 0; i < block_tree_leafs.length (); ++i)
stream_write_tree (ob, block_tree_leafs[i], true);
static void
collect_block_tree_leafs (tree root, vec<tree> &leafs)
{
for (root = BLOCK_SUBBLOCKS (root); root; root = BLOCK_CHAIN (root))
if (! BLOCK_SUBBLOCKS (root))
leafs.safe_push (root);
else
collect_block_tree_leafs (BLOCK_SUBBLOCKS (root), leafs);
}
but the problem is that it is broken, it doesn't cover all block leafs,
but only leafs with an odd depth from DECL_INITIAL (and only some of those).
The following patch fixes that, but I guess we are going to stream at that
point significantly more blocks than before (though I guess most of the time
we'd stream them later on when streaming the gimple_locations that refer to
them).
2020-09-10 Jakub Jelinek <ja...@redhat.com>
* lto-streamer-out.c (collect_block_tree_leafs): Recurse on
root rather than BLOCK_SUBBLOCKS (root).
--- gcc/lto-streamer-out.c.jj 2020-09-10 15:52:36.401413518 +0200
+++ gcc/lto-streamer-out.c 2020-09-10 17:14:24.934503237 +0200
@@ -2294,7 +2294,7 @@ collect_block_tree_leafs (tree root, vec
if (! BLOCK_SUBBLOCKS (root))
leafs.safe_push (root);
else
- collect_block_tree_leafs (BLOCK_SUBBLOCKS (root), leafs);
+ collect_block_tree_leafs (root, leafs);
}
/* This performs function body modifications that are needed for streaming
(gdb) p debug_tree (((tree)0x7fffea71d700)->decl_common.initial)
<block 0x7fffea6f9ea0 used tree_0
supercontext <function_decl 0x7fffea71d700 main
type <function_type 0x7fffea8259d8 type <integer_type 0x7fffea8145e8
int>
QI
size <integer_cst 0x7fffea7f5f60 constant 8>
unit-size <integer_cst 0x7fffea7f5f78 constant 1>
align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7fffea8259d8
arg-types <tree_list 0x7fffea80a8e8 value <void_type 0x7fffea814f18
void>>>
addressable nothrow public static function-specific-target
function-specific-opt decl_5 QI
/usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C:23:1 align:8
warn_if_not_align:0 context <translation_unit_decl 0x7fffea803168
/usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C> initial <block
0x7fffea6f9ea0>
result <result_decl 0x7fffea70de10 D.6516 type <integer_type
0x7fffea8145e8 int>
ignored SI
/usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C:23:11
size <integer_cst 0x7fffea8170c0 constant 32>
unit-size <integer_cst 0x7fffea8170d8 constant 4>
align:32 warn_if_not_align:0 context <function_decl 0x7fffea71d700
main>>
struct-function 0x7fffea714840
chain <var_decl 0x7fffea719120 s type <record_type 0x7fffea71a0a8 S>
addressable used public static read BLK
/usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C:20:69
size <integer_cst 0x7fffea817330 constant 192>
unit-size <integer_cst 0x7fffea817300 constant 24>
align:128 warn_if_not_align:0 context <translation_unit_decl
0x7fffea803168 /usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C> chain
<type_decl 0x7fffea718098 S>>>
subblocks <block 0x7fffea7384e0 used supercontext <block 0x7fffea6f9ea0>
subblocks <block 0x7fffea738540 used supercontext <block 0x7fffea7384e0>
subblocks <block 0x7fffea7385a0 used supercontext <block
0x7fffea738540>
abstract_origin <block 0x7fffea6f9a80 used supercontext
<function_decl 0x7fffea713b00 __ct >>> abstract_origin <block 0x7fffea6f9a80>>
chain <block 0x7fffea7383c0 used supercontext <block 0x7fffea6f9ea0>
subblocks <block 0x7fffea738480 used supercontext <block
0x7fffea7383c0>
^^^^^^^^^^^^^^ HERE
abstract_origin <block 0x7fffea6f9c00 used supercontext
<function_decl 0x7fffea713c00 __dt >>>
chain <block 0x7fffea7381e0 used supercontext <block 0x7fffea6f9ea0>
subblocks <block 0x7fffea738240 used supercontext <block
0x7fffea7381e0>
subblocks <block 0x7fffea7382a0 used supercontext <block
0x7fffea738240> abstract_origin <block 0x7fffea6f9a80>> abstract_origin <block
0x7fffea6f9a80>>
chain <block 0x7fffea6f9f00 used supercontext <block
0x7fffea6f9ea0>
subblocks <block 0x7fffea738000 used supercontext <block
0x7fffea6f9f00> abstract_origin <block 0x7fffea6f9c00>> abstract_origin
<function_decl 0x7fffea717200 __dt_base >> abstract_origin <function_decl
0x7fffea713b00 __ct >> abstract_origin <function_decl 0x7fffea717200 __dt_base
>>
abstract_origin <function_decl 0x7fffea713b00 __ct type <method_type
0x7fffea711498>
addressable asm_written used nothrow public static abstract
external weak autoinline decl_5 QI defer-output
/usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C:14:3 align:16
warn_if_not_align:0 context <translation_unit_decl 0x7fffea803168
/usr/src/gcc-10/gcc/testsuite/g++.dg/ubsan/align-3.C> initial <error_mark
0x7fffea7f5e58> chain <function_decl 0x7fffea717000 __ct_base >>>>
Jakub
