> On Jun 10, 2025, at 09:40, Richard Biener <richard.guent...@gmail.com> wrote:
>
> On Tue, Jun 10, 2025 at 3:37 PM Richard Biener
> <richard.guent...@gmail.com> wrote:
>>
>> On Mon, Jun 9, 2025 at 8:06 PM Qing Zhao <qing.z...@oracle.com> wrote:
>>>
>>>
>>>
>>>> On Jun 6, 2025, at 03:31, Richard Biener <richard.guent...@gmail.com>
>>>> wrote:
>>>>
>>>> On Fri, May 30, 2025 at 5:13 PM Qing Zhao <qing.z...@oracle.com> wrote:
>>>>>
>>>>> Hi, Richard,
>>>>>
>>>>> Really appreciate for your suggestions.
>>>>>
>>>>>> On May 30, 2025, at 05:22, Richard Biener <richard.guent...@gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>> On Fri, May 23, 2025 at 10:49 PM Qing Zhao <qing.z...@oracle.com> wrote:
>>>>>>>
>>>>>>> Hi, Richard,
>>>>>>>
>>>>>>> Thanks a lot for your comments and questions.
>>>>>>> Please see my answers embedded below:
>>>>>>>
>>>>>>>> On May 19, 2025, at 06:44, Richard Biener <richard.guent...@gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>> On Fri, May 16, 2025 at 3:34 PM Qing Zhao <qing.z...@oracle.com> wrote:
>>>>>>>>>
>>>>>>>>> Control this with a new option -fdiagnostics-details.
>>>>>>>>>
>>>>>>>>> $ cat t.c
>>>>>>>>> extern void warn(void);
>>>>>>>>> static inline void assign(int val, int *regs, int *index)
>>>>>>>>> {
>>>>>>>>> if (*index >= 4)
>>>>>>>>> warn();
>>>>>>>>> *regs = val;
>>>>>>>>> }
>>>>>>>>> struct nums {int vals[4];};
>>>>>>>>>
>>>>>>>>> void sparx5_set (int *ptr, struct nums *sg, int index)
>>>>>>>>> {
>>>>>>>>> int *val = &sg->vals[index];
>>>>>>>>>
>>>>>>>>> assign(0, ptr, &index);
>>>>>>>>> assign(*val, ptr, &index);
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> $ gcc -Wall -O2 -c -o t.o t.c
>>>>>>>>> t.c: In function ‘sparx5_set’:
>>>>>>>>> t.c:12:23: warning: array subscript 4 is above array bounds of
>>>>>>>>> ‘int[4]’ [-Warray-bounds=]
>>>>>>>>> 12 | int *val = &sg->vals[index];
>>>>>>>>> | ~~~~~~~~^~~~~~~
>>>>>>>>> t.c:8:18: note: while referencing ‘vals’
>>>>>>>>> 8 | struct nums {int vals[4];};
>>>>>>>>> | ^~~~
>>>>>>>>>
>>>>>>>>> In the above, Although the warning is correct in theory, the warning
>>>>>>>>> message
>>>>>>>>> itself is confusing to the end-user since there is information that
>>>>>>>>> cannot
>>>>>>>>> be connected to the source code directly.
>>>>>>>>>
>>>>>>>>> It will be a nice improvement to add more information in the warning
>>>>>>>>> message
>>>>>>>>> to report where such index value come from.
>>>>>>>>>
>>>>>>>>> In order to achieve this, we add a new data structure "move_history"
>>>>>>>>> to record
>>>>>>>>> 1. the "condition" that triggers the code movement;
>>>>>>>>> 2. whether the code movement is on the true path of the "condition";
>>>>>>>>> 3. the "compiler transformation" that triggers the code movement.
>>>>>>>>>
>>>>>>>>> Whenever there is a code movement along control flow graph due to some
>>>>>>>>> specific transformations, such as jump threading, path isolation, tree
>>>>>>>>> sinking, etc., a move_history structure is created and attached to the
>>>>>>>>> moved gimple statement.
>>>>>>>>>
>>>>>>>>> During array out-of-bound checking or -Wstringop-* warning checking,
>>>>>>>>> the
>>>>>>>>> "move_history" that was attached to the gimple statement is used to
>>>>>>>>> form
>>>>>>>>> a sequence of diagnostic events that are added to the corresponding
>>>>>>>>> rich
>>>>>>>>> location to be used to report the warning message.
>>>>>>>>>
>>>>>>>>> This behavior is controled by the new option -fdiagnostics-details
>>>>>>>>> which is off by default.
>>>>>>>>>
>>>>>>>>> With this change, by adding -fdiagnostics-details,
>>>>>>>>> the warning message for the above testing case is now:
>>>>>>>>>
>>>>>>>>> $ gcc -Wall -O2 -fdiagnostics-details -c -o t.o t.c
>>>>>>>>> t.c: In function ‘sparx5_set’:
>>>>>>>>> t.c:12:23: warning: array subscript 4 is above array bounds of
>>>>>>>>> ‘int[4]’ [-Warray-bounds=]
>>>>>>>>> 12 | int *val = &sg->vals[index];
>>>>>>>>> | ~~~~~~~~^~~~~~~
>>>>>>>>> ‘sparx5_set’: events 1-2
>>>>>>>>> 4 | if (*index >= 4)
>>>>>>>>> | ^
>>>>>>>>> | |
>>>>>>>>> | (1) when the condition is evaluated to true
>>>>>>>>> ......
>>>>>>>>> 12 | int *val = &sg->vals[index];
>>>>>>>>> | ~~~~~~~~~~~~~~~
>>>>>>>>> | |
>>>>>>>>> | (2) out of array bounds here
>>>>>>>>> t.c:8:18: note: while referencing ‘vals’
>>>>>>>>> 8 | struct nums {int vals[4];};
>>>>>>>>> | ^~~~
>>>>>>>>>
>>>>>>>>> The change was divided into 3 parts:
>>>>>>>>>
>>>>>>>>> Part 1: Add new data structure move_history, record move_history
>>>>>>>>> during
>>>>>>>>> transformation;
>>>>>>>>> Part 2: In warning analysis, Use the new move_history to form a rich
>>>>>>>>> location with a sequence of events, to report more context info
>>>>>>>>> of the warnings.
>>>>>>>>> Part 3: Add debugging mechanism for move_history.
>>>>>>>>
>>>>>>>> Thanks for working on this. I'm pasting my review notes on [1/3]
>>>>>>>> below.
>>>>>>>>
>>>>>>>>
>>>>>>>> ove histories are allocated from a global obstack - it seems they are
>>>>>>>> never released, just the association between stmt and history is
>>>>>>>> eventually broken by remove_move_history?
>>>>>>>
>>>>>>> They are supposed to be released by the following routine:
>>>>>>>
>>>>>>> +void
>>>>>>> +move_history_finalize (void)
>>>>>>> +{
>>>>>>> + if (move_history_map)
>>>>>>> + {
>>>>>>> + delete move_history_map;
>>>>>>> + move_history_map = NULL;
>>>>>>> + }
>>>>>>> + obstack_free (&move_history_obstack, NULL);
>>>>>>> + return;
>>>>>>> +}
>>>>>>>
>>>>>>> Is the above “obstack_free” the proper utility routine that are used to
>>>>>>> free the whole
>>>>>>> memory allocated for the“move_history_obstack”?
>>>>>>>
>>>>>>> If not, please advise on how to free the obstacle variables.
>>>>>>
>>>>>> Yes, the above releases them all - I was pointing out that when
>>>>>> an entry becomes unreachable via remove_move_history the
>>>>>> entry doesn't get re-used but instead is only released at the end
>>>>>> of compilation.
>>>>>
>>>>> Okay, I see.
>>>>> So in the following code:
>>>>>
>>>>> @@ -581,6 +582,8 @@ gsi_remove (gimple_stmt_iterator *i, bool
>>>>> remove_permanently)
>>>>> cfun->debug_marker_count--;
>>>>> require_eh_edge_purge = remove_stmt_from_eh_lp (stmt);
>>>>> gimple_remove_stmt_histograms (cfun, stmt);
>>>>> + if (get_move_history (stmt) != NULL)
>>>>> + remove_move_history (stmt);
>>>>>
>>>>> +/* Remove the move history for STMT. */
>>>>> +
>>>>> +void
>>>>> +remove_move_history (gimple *stmt)
>>>>> +{
>>>>> + if (!move_history_map)
>>>>> + return;
>>>>> + move_history_map->remove (stmt);
>>>>> + return;
>>>>> +}
>>>>>
>>>>> What’s in my original thought is, whenever one gimple stmt is deleted, We
>>>>> just break the
>>>>> association between It and its move_history, the real move_history data
>>>>> structure will
>>>>> be released by obstack_free anyway later.
>>>>>
>>>>> Yes, you are right, if there are many gimple stmts with move_histories
>>>>> are deleted during
>>>>> the optimization, it’s better to delete the associated move_history data
>>>>> structure too in
>>>>> “remove_move_history”.
>>>>> Will update it.
>>>>>
>>>>>>
>>>>>>>> Do you have any statistics
>>>>>>>> on the memory usage?
>>>>>>> No.
>>>>>>>> Might be an interesting bit to dump with
>>>>>>>> -fmem-report (the size of the obstack). Likewise the statistics
>>>>>>>> on the hash-map are interesting.
>>>>>>>
>>>>>>> Are you suggesting to add the memory usage statistics for both
>>>>>>> “move_history_obstack” and
>>>>>>> “move_history_map” to -fmem_report?
>>>>>>> If so, I will study a little bit on how to do this. And then add this
>>>>>>> part.
>>>>>>
>>>>>> Yes. Basically to get an idea how bad the lack of re-use is. I could
>>>>>> imagine
>>>>>> the obstack could be per function which might improve peak memory use,
>>>>>> or adding a ref counter and keeping a freelist. Without data it's hard
>>>>>> to tell
>>>>>> whether this is worth the trouble.
>>>>>
>>>>> Sure, I will collect these statistics with GCC build as you suggested.
>>>>> (But maybe I don’t need to
>>>>> collect them anymore due to the new approach you suggested-:).
>>>>>>
>>>>>>>
>>>>>>>> static bool
>>>>>>>> +is_move_history_existed (location_t cond_location, bool is_true_path,
>>>>>>>> + enum move_reason
>>>>>>>>
>>>>>>>> that's a bit of an odd name - 'move_history_exists_p'?
>>>>>>>
>>>>>>> Okay, will update the name as you suggested.
>>>>>>>
>>>>>>>> What are
>>>>>>>> we supposed to do on a duplicate? This is a linear search - how
>>>>>>>> many do we accumulate in practice? Does it make sense to put a
>>>>>>>> limit on the number of transforms we record?
>>>>>>>
>>>>>>> Yeah, all are good questions.
>>>>>>> I cannot imagine a concrete situation in which the duplication might
>>>>>>> happen,
>>>>>>> But I assume that it (the duplication) might happen (might due to
>>>>>>> interaction among
>>>>>>> different transformations within loops?).
>>>>>>> Shall we collect some statistics on the potential duplications? And
>>>>>>> also the length of the
>>>>>>> move_history chain? And then decide the solution to the above
>>>>>>> questions?
>>>>>>
>>>>>> Yes.
>>>>>>
>>>>>>> If so, do you have a suggestion on what benchmark I should use to
>>>>>>> collect such
>>>>>>> Data? Is SPECCPU good enough for such purpose?
>>>>>>
>>>>>> I think even data from a GCC build is useful enough.
>>>>> Okay, will collect all the above data with GCC build if needed. (But
>>>>> looks like I don’t need
>>>>> To do this if the new approach works well)
>>>>>>
>>>>>>>>
>>>>>>>> static gimple *
>>>>>>>> +get_cond_stmt (edge entry, bool is_destination, bool *is_true_path)
>>>>>>>> +{
>>>>>>>>
>>>>>>>> I don't quite understand the is_destination parameter, likewise
>>>>>>>> for the two APIs using this function?
>>>>>>>
>>>>>>> The major purpose of “is_destination” is:
>>>>>>> the value of “is_destination” is used to compute the value of
>>>>>>> “is_true_path” as:
>>>>>>>
>>>>>>> + *is_true_path = !(is_branch_taken ^ is_destination);
>>>>>>>
>>>>>>> As now, only GIMPLE_COND is considered, GIMPLE_SWITCH is not handled.
>>>>>>> We can extend this work to include GIMPLE_SWITCH if needed. What’s your
>>>>>>> Suggestions on this?
>>>>>>>
>>>>>>> Since only GIMPLE_COND is handled now, there will be two places where
>>>>>>> the
>>>>>>> code might move to, one is the “destination” of the current edge, one
>>>>>>> is not the
>>>>>>> “destination” of the current edge, i.e, its on the destination of the
>>>>>>> new edge.
>>>>>>>
>>>>>>> Then based on whether the current edge is a taken edge and whether the
>>>>>>> code is
>>>>>>> moved to the destination of this current edge, we can compute whether
>>>>>>> the code
>>>>>>> moved to the destination of this current edge is on the TRUE path of
>>>>>>> the COND
>>>>>>> Stmt. and report such information to the end users. (Please see my
>>>>>>> explanation
>>>>>>> on the isolate path transformation below, there is a graph to explain
>>>>>>> this -:).
>>>>>>>
>>>>>>> Hope this is clear, if it is still not clear, let me know, I will try
>>>>>>> to explain more.
>>>>>>
>>>>>> Hmm, I'm not sure yet ;)
>>>>>>
>>>>>>>
>>>>>>>> Usually the control edge
>>>>>>>
>>>>>>> What do you mean by the control edge?
>>>>>>
>>>>>> The control edge is the edge out of the control stmt that decides
>>>>>> whether the
>>>>>> outgoing edge (which IIRC is passed here) is executed. Consider
>>>>>>
>>>>>> if (...)
>>>>>> \ e'
>>>>>> \
>>>>>> if (..)
>>>>>> / \
>>>>>> A B
>>>>>> \ /
>>>>>> C
>>>>>> | e
>>>>>>
>>>>>> here 'e' would be the outgoing edge, but rather than the if() before
>>>>>> the diamond, the if() controlling e' is the control edge.
>>>>>
>>>>> Yes, that’s what in my mind too.
>>>>>>
>>>>>>>> and the BB the stmt is in can be different from edge->dest, and
>>>>>>>> I'd expect the callers to know, so I wonder why we would want to
>>>>>>>> search here?
>>>>>>>
>>>>>>> Not quite understand the question. Is my graph below for the isolate
>>>>>>> path
>>>>>>> transformation answer this question?
>>>>>>
>>>>>> I think how it actually works depends on the code transform, but see one
>>>>>> of
>>>>>> my last comments where the abstraction presented is maybe not best.
>>>>>>
>>>>>>>> In particular the use in path isolation for PHI
>>>>>>>> arguments passes in the edge of the problematic PHI arg but
>>>>>>>> the first reached gcond * might not be the full controlling
>>>>>>>> condition when there is more than two PHI arguments.
>>>>>>>
>>>>>>> For path isolation, I have the following patch:
>>>>>>>
>>>>>>> @@ -170,6 +171,16 @@ isolate_path (basic_block bb, basic_block
>>>>>>> duplicate, edge e.
>>>>>>> }
>>>>>>> bb->count -= count;
>>>>>>>
>>>>>>> + /* Set the move history for all the stmts in both original and copied
>>>>>>> + basic blocks. The duplicated block will be the destination of the
>>>>>>> + incoming edge. */
>>>>>>> + if (flag_diagnostics_details)
>>>>>>> + {
>>>>>>> + set_move_history_to_stmts_in_bb (bb, e, false,
>>>>>>> COPY_BY_ISOLATE_PATH);
>>>>>>> + set_move_history_to_stmts_in_bb (duplicate, e,
>>>>>>> + true, COPY_BY_ISOLATE_PATH);
>>>>>>> + }
>>>>>>> +
>>>>>>>
>>>>>>> From my understanding:
>>>>>>> the arguments “bb”, “duplicate” and “e” of the routine “isolate_path”
>>>>>>> can be illustrated as following:
>>>>>>>
>>>>>>> OLD:
>>>>>>> cond_bb
>>>>>>> \ | /
>>>>>>> e1 \ | e / e2
>>>>>>> V
>>>>>>> bb
>>>>>>>
>>>>>>> NEW:
>>>>>>> cond_bb
>>>>>>> \ / |
>>>>>>> e1\ / e2 | e
>>>>>>> V V
>>>>>>> bb duplicate
>>>>>>>
>>>>>>> Is the above transformation correct?
>>>>>>
>>>>>> more-or-less, yes. path isolation only handles the case where there's
>>>>>> a gimple-cond on the incoming
>>>>>> edge to BB that will cause UB in BB. So we want to remove that edge
>>>>>> from BB and instead have a
>>>>>> copy which we can prune at/after the UB stmt.
>>>>>
>>>>> Yes. That’s right.
>>>>>>
>>>>>>> If yes, then the “duplicate” is the destination of the edge “e”, but
>>>>>>> the “bb” is not the destination of the edge “e”.
>>>>>>> Therefore:
>>>>>>>
>>>>>>> + set_move_history_to_stmts_in_bb (bb, e, false,
>>>>>>> COPY_BY_ISOLATE_PATH);
>>>>>>> + set_move_history_to_stmts_in_bb (duplicate, e,
>>>>>>> + true, COPY_BY_ISOLATE_PATH);
>>>>>>>
>>>>>>> Then, the above two calls to the routine
>>>>>>> “set_move_history_to_stmts_in_bb” will get the cond stmt “cond” in the
>>>>>>> source basic block “cond_bb” of the edge “e” if the condition stmt can
>>>>>>> be found. And then set the move_history
>>>>>>> for each stmt in the block “bb” or “duplicate” properly.
>>>>>>> (If the condition stmt cannot be found, we give up).
>>>>>>>
>>>>>>> Is the above correct?
>>>>>>
>>>>>> So what I wondered is why we record the stmts in 'bb' to be "moved"? Or
>>>>>> why we
>>>>>> record the stmts in 'duplicate' to be "moved"? That is, what's the
>>>>>> condition that's
>>>>>> no longer visible in the IL that we want to preserve this way?
>>>>>>
>>>>>> I think both that in 'bb' 'cond' is false and that in 'duplicate'
>>>>>> 'cond' is true is still
>>>>>> obviously present, so it's redundant to note this? So what we get from
>>>>>> marking
>>>>>> the stmts is just that "stmt somehow participates in an optimization
>>>>>> where 'cond'
>>>>>> was involved"?
>>>>>>
>>>>>> That is, I wonder whether if -fdiagnostic-show-context would simply
>>>>>> display
>>>>>> the (first) control stmt (that is still in the IL!) of its execution
>>>>>> context, whether
>>>>>> that would fix all the testcases you include?
>>>>> Oh, yeah, all the above sound very reasonable and natural to me -:)
>>>>> I guess that I was misleaded by the compiler transformations….
>>>>>
>>>>> Maybe Not only the “first” control stmt, tracking back along the CFG to
>>>>> the first joint place, i.e:
>>>>>
>>>>> + B2
>>>>> + / \
>>>>> + V \
>>>>> + B3 \
>>>>> + / \ \
>>>>> + V \---->V
>>>>> + B4 B7
>>>>> +
>>>>>
>>>>> If the diagnostic happens in B4, and there is only one incoming edge to
>>>>> B4, will track back to B3 and then back to B2.
>>>>> Report the condition on B2, B3, and whether B3 and B4 is on the
>>>>> TRUE/FALSE patch of the corresponding edges.
>>>>>
>>>>> On the other hand, if the diagnostic happens in B7, since there are
>>>>> multiple incoming edges to B7, -fdiagnostic-show-context
>>>>> will give up on such case.
>>>>
>>>> In principle it should be possible to collect a complex condition like
>>>> A && B || C from the CFG. Of course the question is how much is
>>>> interesting or even relevant - it's going to be hard to guess.
>>> Yes. That’s right.
>>> It might not be helpful to report the complete condition chain for the
>>> specific diagnostic.
>>> So the major question is:
>>> what kind of algorithm or heuristic we should use to pick up the specific
>>> portion of the condition
>>> chain for the diagnostic to help the end-user to understand the message
>>> better?
>>>
>>> What kind of factors might impact the heuristic: (the following are just my
>>> guess)
>>>
>>> 1. The algorithm or heuristic for the value ranger analysis?
>>> 2. Different warnings might have different heuristic?
>>> 3. Only compiler optimization altered control edges?
>>>
>>> What else?
>>>
>>> Any suggestion on this?
>>
>> It's difficult to do any meaningful pruning I think. Consider
>>
>> if (i == -1)
>> tem = a[i];
>>
>> when we transform this to
>>
>> if (i == -1)
>> tem = a[-1];
>>
>> and report the out-of-bounds access then we've lost the fact
>> that -1 was originally 'i' and there's an interesting condition on that
>> variable. So unless we preserve some kind of optimization history
>> on a stmt like the above we are lost. The same is true for
>> "altered" control edges where the most interesting are again those
>> that are elided by optimization (the implied true/false conditions).
>>
>> That said, I would expect the user to not use -fdiagnostics-show-context by
>> default but instead when being puzzled about a diagnostic, turn it on
>> on-demand. So it's probably useful to report all of the chain or maybe
>> have -fdiagnostic-show-context=N with N limiting the depth (or a separate
>> knob for this).
>>
>> When there's still 'i' in a[i] but we figured out a range then we can see
>> to do 1. to gather conditions that we consider. The backwards threader
>> has "interestingness" heuristics that could eventually be repurposed.
>> The "good" thing is that once we decide to emit a diagnostic it's fair
>> to spend quite some cycles on improving it.
>
> So as a summary I'd say we'd want to have -fdiagnostic-show-context
> (=1 for now) and simply display the immediate control condition for
> the select diagnostics your patch series handled and start from there,
> adding test coverage where that's useful (like for my simple a[i] example
> above) and see in what cases that's lacking.
Thanks for the summary, I agree.
The following is my plan:
1. The first working version of -fdiagnostic-show-context=N should cover all
the current
known testing cases: all the PRs and your testing case and Kees’s new testing
case.
2. Then we can improve it later if new uncovered testing case is reported.
Is this reasonable?
Qing
>
> Richard.
>
>>>>
>>>>>
>>>>>>
>>>>>> Now, when we actually elide a control stmt, that's the point where we
>>>>>> lose
>>>>>> information, but the transforms altered, jump threading, path
>>>>>> isolation and sinking,
>>>>>> don't actually do this?
>>>>> Yes.
>>>>>>
>>>>>> And if we record the stmt "move" for both edges don't we end up creating
>>>>>> too much noise that will be perceived as fals positive / misleading when
>>>>>> we extend the use of this?
>>>>>>
>>>>>> So like, when path isolation isolates a ptr == 0 we should end up with IL
>>>>>> like
>>>>>>
>>>>>> if (ptr != 0)
>>>>>> | \
>>>>>> | good code
>>>>>> |
>>>>>> *0 = x;
>>>>>>
>>>>>> where the last stmt is eventually diagnosed. But the test on ptr
>>>>>> will have survived, so if we'd diagnose the path to it that would
>>>>>> help already, no need for any magic stmt duplication/move marking?
>>>>>
>>>>> Right, that should be enough.
>>>>>
>>>>>>
>>>>>> I'm not saying that for some cases we will need that, but the testcaes
>>>>>> seem to be too simple to prove this?
>>>>>>
>>>>>> That said, we might be able to do with the 2nd patch improving
>>>>>> the actual diagnostic but simply by making it show a path
>>>>>> with -fdiagnostic-show-context?
>>>>>
>>>>> I will try this approach to see whether it can catch all the cases.
>>>>> And whether there is any issue we miss at this moment.
>>>>
>>>> Thanks. I guess if we're collecting a complex condition like
>>>> suggested above we could also try hard to prove it false
>>>> so we can prune diagnostics on unreachable code that we just
>>>> didn't optimize.
>>>
>>> Has such analysis (prove one path false) been done by the compiler already?
>>
>> Yes, for example jump-threading can do this. But the transforms are limited
>> by
>> costing, for example on code duplication. So there's the chance that extra
>> static analysis can prove unreachability (and we always have the cases with
>> bad luck of pass ordering or too late removal of dead code).
>>
>>> Such analysis also relates to value range analysis and propagation? (Since
>>> evaluating a condition
>>> to TRUE/FALSE need to know the value ranges of the variables in the
>>> condition)
>>
>> value ranges can help, yes.
>>
>>>> There is (a quite imperfect) code for analyzing
>>>> and simplifying predicates in gimple-predicate-analysis.{cc,h}.
>>>> The predicate build from a CFG isn't fully exposed in the API
>>>> though.
>>>
>>> I just briefly read these files and see that it is currently used by
>>> uninitialized analysis.
>>> I haven’t gone into details of how this help uninitialized analysis, but I
>>> guess it’s used
>>> to evaluate the path in order to rule out false-positive warnings?
>>
>> It's used the other way around - it tries to prove that on all paths
>> to a use a variable
>> is initialized. If we fail to prove that we diagnose.
>>
>>> Might need to understand how uninitialized analysis use the predicate
>>> analysis first to see how to use it
>>> for my purpose.
>>
>> What you'd do is try to prove the condition guarding the stmt we are
>> diagnosing
>> is false. I'm not sure if it helps in practice, of course. It's
>> really poor mans
>> static analysis and easily confused by late transforms.
>>
>> Richard.
>>
>>> thanks.
>>>
>>> Qing
>>>>
>>>>>>
>>>>>>>> Not to
>>>>>>>> mention a switch statement might also be the control stmt.
>>>>>>>> While this can be extended in future I'd like the caller
>>>>>>>> to compute the control dependence that's relevant - using
>>>>>>>> an edge (or in future a vector of edges) is fine, it should
>>>>>>>> be the edge outgoing from the control stmt.
>>>>>>>
>>>>>>> Yes, that’s the edge outgoing from the cond stmt.
>>>>>>>>
>>>>>>>> @opindex fdiagnostics-details
>>>>>>>> +@item -fdiagnostics-details
>>>>>>>>
>>>>>>>> Not entirely happy with the name, we have -fdiagnostic-show-*
>>>>>>>> options related to events, so maybe -fdiagnostic-show-details
>>>>>>>> or -fdiagnostic-show-context?
>>>>>>>
>>>>>>> -fdiagnostic-show-context is better?
>>>>>>
>>>>>> I'd think so.
>>>>>>
>>>>>>>>
>>>>>>>> @@ -581,6 +582,8 @@ gsi_remove (gimple_stmt_iterator *i, bool
>>>>>>>> remove_permanently)
>>>>>>>> cfun->debug_marker_count--;
>>>>>>>> require_eh_edge_purge = remove_stmt_from_eh_lp (stmt);
>>>>>>>> gimple_remove_stmt_histograms (cfun, stmt);
>>>>>>>> + if (get_move_history (stmt) != NULL)
>>>>>>>> + remove_move_history (stmt);
>>>>>>>>
>>>>>>>> I'd say make remove_move_history cope with the stmt not being in the
>>>>>>>> hash is better, so just call that function here, without get_*()
>>>>>>>
>>>>>>> Okay.
>>>>>>>>
>>>>>>>> @ -712,6 +756,19 @@ sink_code_in_bb (basic_block bb,
>>>>>>>> virtual_operand_live &vop_live)
>>>>>>>> bb->index, (gsi_bb (togsi))->index);
>>>>>>>> }
>>>>>>>>
>>>>>>>> + /* Set the move history for the stmt that is sinked from BB to
>>>>>>>> + gsi_bb (togsi). This stmt is on the path from BB to
>>>>>>>> + gsi_bb (togsi). */
>>>>>>>> + if (flag_diagnostics_details)
>>>>>>>> + {
>>>>>>>> + /* BB might not be the immediate predecessor of gsi_bb
>>>>>>>> (togsi),
>>>>>>>> + get the edge chain from BB to gsi_bb (togsi). */
>>>>>>>> + auto_vec<edge> edge_chain = get_edge_chain (bb, gsi_bb
>>>>>>>> (togsi));
>>>>>>>> +
>>>>>>>> + for (edge entry : edge_chain)
>>>>>>>> + set_move_history_to_stmt (stmt, entry, true, MOVE_BY_SINK);
>>>>>>>> + }
>>>>>>>>
>>>>>>>> so you represent a more complex control condition by a series of
>>>>>>>> sinkings?
>>>>>>>
>>>>>>> If the sinking happens along a path that contain multiple edges such as
>>>>>>> the following
>>>>>>> B2 to B4:
>>>>>>>
>>>>>>> +/* Get the edge chain from FROM_BB to TO_BB, FROM_BB dominates TO_BB.
>>>>>>> + B2
>>>>>>> + / \
>>>>>>> + V \
>>>>>>> + B3 \
>>>>>>> + / \ \
>>>>>>> + V \---->V
>>>>>>> + B4 B7
>>>>>>> +
>>>>>>> + In the above CFG, FROM_BB is B2, TO_BB is B4. This routine
>>>>>>> + will locate two edges, B2->B3, and B3->B4 and return a vector
>>>>>>> + with these two edges.
>>>>>>> + This routine will return an empty vector if the control flow
>>>>>>> + edge chain from FROM_BB to TO_BB is too complicate. */
>>>>>>> +
>>>>>>>
>>>>>>> Then both the edges B2->B3 and B3->B4 will be recorded. And the sinking
>>>>>>> from B2->B3
>>>>>>> is on the destination of this edge, and then sinking from B3->B4 also
>>>>>>> is on the destination
>>>>>>> of this edge too.
>>>>>>> Therefore, we have:
>>>>>>>
>>>>>>> + for (edge entry : edge_chain)
>>>>>>> + set_move_history_to_stmt (stmt, entry, true, MOVE_BY_SINK);
>>>>>>> + }
>>>>>>>
>>>>>>>
>>>>>>>> I guess that's possible in this case at least. I'll note the
>>>>>>>> get_edge_chain function seems to be quite simplistic and likely
>>>>>>>> prone to record only a part of the sinkings.
>>>>>>>
>>>>>>> Could you please explain a bit more here? Do you mean that the current
>>>>>>> “get_edge_chain” might miss some more complicate cases? If so, could you
>>>>>>> please provide more details on what’s the more complicate cases look
>>>>>>> like?
>>>>>>> Then I will enhance this routine to handle them.
>>>>>>>>
>>>>>>>> + /* Set the move history for all the stmts in both original
>>>>>>>> and copied
>>>>>>>> + basic blocks. The duplicated block will be the
>>>>>>>> destination of the
>>>>>>>> + incoming edge. */
>>>>>>>> + if (flag_diagnostics_details)
>>>>>>>> + {
>>>>>>>> + set_move_history_to_stmts_in_bb (e->dest, e, false,
>>>>>>>> + COPY_BY_THREAD_JUMP);
>>>>>>>> + set_move_history_to_stmts_in_bb (rd->dup_blocks[0], e,
>>>>>>>> + true,
>>>>>>>> COPY_BY_THREAD_JUMP);
>>>>>>>> + }
>>>>>>>>
>>>>>>>> I'm taking this one as example - why are we setting a move history
>>>>>>>> on the not copied part? Shouldn't that be still within the original
>>>>>>>> constraints / location? Otherwise why would(nt) we show the location
>>>>>>>> and direction of all control stmts of a stmts we emit a diagnostic on?
>>>>>>>
>>>>>>> I think that the following should answer the above questions:
>>>>>>> https://gcc.gnu.org/pipermail/gcc-patches/2024-October/666870.html
>>>>>>>
>>>>>>> "
>>>>>>> The key feature of the compiler transformation that might provide more
>>>>>>> accurate information to the value-range analysis is: moving a statement
>>>>>>> from the joint point of one specific condition to this condition's
>>>>>>> TRUE or FALSE path.
>>>>>>>
>>>>>>> For example, threadjump and isolate-path transformation make a
>>>>>>> duplicated
>>>>>>> basic block “Ba’ " of the original basic block "Ba" that on the joint
>>>>>>> point of a condition "cond", and then move the two basic block “Ba' "
>>>>>>> and "Ba" to the TRUE path and FALSE path of the condition "cond"; on the
>>>>>>> otherhand, tree sink transformation just move some of the statements
>>>>>>> from
>>>>>>> the joint point of a condition "cond" to one specific path of this
>>>>>>> condition.
>>>>>>>
>>>>>>> So, the new data structure "move_history" will include the following
>>>>>>> information:
>>>>>>> A. the "condition" that triggers the code movement;
>>>>>>> B. whether the code movement is on the true path of the "condition";
>>>>>>> C. the "compiler transformation" that triggers the code movement.
>>>>>>> "
>>>>>>>
>>>>>>> Does the above answer your question?
>>>>>>
>>>>>> Yes, I understand what we record. But I still wonder if we need this.
>>>>>> What we do not record reliably is when if (A) eventually is optimized
>>>>>> to if (1) or if (0) that the stmts on the path that remains are subject
>>>>>> to A == 1 (or 0).
>>>>>
>>>>> Yes, I understand what you suggested and I like this idea. That’s much
>>>>> simple
>>>>> and natural to this problem.
>>>>> I will try to implement this approach in the next version to see whether
>>>>> there is any
>>>>> potential issue with it.
>>>>>
>>>>> Really appreciate for your suggestions and help.
>>>>>
>>>>> FYI, I will be on vacation next week, so will try the new approach when I
>>>>> am back
>>>>> on the week of 6/9.
>>>>
>>>> No problem.
>>>>
>>>> Richard.
>>>>
>>>>> Thanks again.
>>>>>
>>>>> Qing
>>>>>
>>>>>
>>>>>> Richard.
>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> I think it makes sense to squash [3/3] into this patch.
>>>>>>>
>>>>>>> Okay, will do that,
>>>>>>>>
>>>>>>>> There is documentation about diagnostics in doc/ux.texi, it would be
>>>>>>>> nice to mention move-history there.
>>>>>>>
>>>>>>> Okay, will study a little bit and add it.
>>>>>>>
>>>>>>> Thanks again for your time and comments.
>>>>>>>
>>>>>>> Qing
>>>>>>>>
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Richard.
>>>>>>>>
>>>>>>>>> PR tree-optimization/109071
>>>>>>>>> PR tree-optimization/85788
>>>>>>>>> PR tree-optimization/88771
>>>>>>>>> PR tree-optimization/106762
>>>>>>>>> PR tree-optimization/108770
>>>>>>>>> PR tree-optimization/115274
>>>>>>>>> PR tree-optimization/117179
>>>>>>>>>
>>>>>>>>> gcc/ChangeLog:
>>>>>>>>>
>>>>>>>>> * Makefile.in (OBJS): Add diagnostic-move-history.o.
>>>>>>>>> * gcc/common.opt (fdiagnostics-details): New option.
>>>>>>>>> * gcc/doc/invoke.texi (fdiagnostics-details): Add
>>>>>>>>> documentation for the new option.
>>>>>>>>> * gimple-iterator.cc (gsi_remove): (gsi_remove): Remove the move
>>>>>>>>> history when removing the gimple.
>>>>>>>>> * gimple-pretty-print.cc (pp_gimple_stmt_1): Emit MV_H marking
>>>>>>>>> if the gimple has a move_history.
>>>>>>>>> * gimple-ssa-isolate-paths.cc (isolate_path): Set move history
>>>>>>>>> for the gimples of the duplicated blocks.
>>>>>>>>> * tree-ssa-sink.cc (sink_code_in_bb): Create move_history for
>>>>>>>>> stmt when it is sinked.
>>>>>>>>> * toplev.cc (toplev::finalize): Call move_history_finalize.
>>>>>>>>> * tree-ssa-threadupdate.cc (ssa_redirect_edges): Create
>>>>>>>>> move_history
>>>>>>>>> for stmts when they are duplicated.
>>>>>>>>> (back_jt_path_registry::duplicate_thread_path): Likewise.
>>>>>>>>> * diagnostic-move-history.cc: New file.
>>>>>>>>> * diagnostic-move-history.h: New file.
>>>>>>>>>
>>>>>>>>> gcc/testsuite/ChangeLog:
>>>>>>>>>
>>>>>>>>> * gcc.dg/pr117375.c: New test.
>>>>>>>>> ---
>>>>>>>>> gcc/Makefile.in | 1 +
>>>>>>>>> gcc/common.opt | 4 +
>>>>>>>>> gcc/diagnostic-move-history.cc | 265 ++++++++++++++++++++++++++++++++
>>>>>>>>> gcc/diagnostic-move-history.h | 92 +++++++++++
>>>>>>>>> gcc/doc/invoke.texi | 11 ++
>>>>>>>>> gcc/gimple-iterator.cc | 3 +
>>>>>>>>> gcc/gimple-pretty-print.cc | 4 +
>>>>>>>>> gcc/gimple-ssa-isolate-paths.cc | 11 ++
>>>>>>>>> gcc/testsuite/gcc.dg/pr117375.c | 13 ++
>>>>>>>>> gcc/toplev.cc | 3 +
>>>>>>>>> gcc/tree-ssa-sink.cc | 57 +++++++
>>>>>>>>> gcc/tree-ssa-threadupdate.cc | 25 +++
>>>>>>>>> 12 files changed, 489 insertions(+)
>>>>>>>>> create mode 100644 gcc/diagnostic-move-history.cc
>>>>>>>>> create mode 100644 gcc/diagnostic-move-history.h
>>>>>>>>> create mode 100644 gcc/testsuite/gcc.dg/pr117375.c
>>>>>>>>>
>>>>>>>>> diff --git a/gcc/Makefile.in b/gcc/Makefile.in
>>>>>>>>> index 72d132207c0..38dfb688e60 100644
>>>>>>>>> --- a/gcc/Makefile.in
>>>>>>>>> +++ b/gcc/Makefile.in
>>>>>>>>> @@ -1451,6 +1451,7 @@ OBJS = \
>>>>>>>>> df-problems.o \
>>>>>>>>> df-scan.o \
>>>>>>>>> dfp.o \
>>>>>>>>> + diagnostic-move-history.o \
>>>>>>>>> digraph.o \
>>>>>>>>> dojump.o \
>>>>>>>>> dominance.o \
>>>>>>>>> diff --git a/gcc/common.opt b/gcc/common.opt
>>>>>>>>> index 0e50305dde8..081537c349a 100644
>>>>>>>>> --- a/gcc/common.opt
>>>>>>>>> +++ b/gcc/common.opt
>>>>>>>>> @@ -1613,6 +1613,10 @@ fdiagnostics-minimum-margin-width=
>>>>>>>>> Common Joined UInteger Var(diagnostics_minimum_margin_width) Init(6)
>>>>>>>>> Set minimum width of left margin of source code when showing source.
>>>>>>>>>
>>>>>>>>> +fdiagnostics-details
>>>>>>>>> +Common Var(flag_diagnostics_details)
>>>>>>>>> +Collect and print more context information for diagnostics.
>>>>>>>>> +
>>>>>>>>> fdisable-
>>>>>>>>> Common Joined RejectNegative Var(common_deferred_options) Defer
>>>>>>>>> -fdisable-[tree|rtl|ipa]-<pass>=range1+range2 Disable an
>>>>>>>>> optimization pass.
>>>>>>>>> diff --git a/gcc/diagnostic-move-history.cc
>>>>>>>>> b/gcc/diagnostic-move-history.cc
>>>>>>>>> new file mode 100644
>>>>>>>>> index 00000000000..83d8a42b577
>>>>>>>>> --- /dev/null
>>>>>>>>> +++ b/gcc/diagnostic-move-history.cc
>>>>>>>>> @@ -0,0 +1,265 @@
>>>>>>>>> +/* Functions to handle move history.
>>>>>>>>> + Copyright (C) 2024 Free Software Foundation, Inc.
>>>>>>>>> + Contributed by Qing Zhao <qing.z...@oracle.com>
>>>>>>>>> +
>>>>>>>>> + This file is part of GCC.
>>>>>>>>> +
>>>>>>>>> + GCC is free software; you can redistribute it and/or modify it
>>>>>>>>> under
>>>>>>>>> + the terms of the GNU General Public License as published by the
>>>>>>>>> Free
>>>>>>>>> + Software Foundation; either version 3, or (at your option) any
>>>>>>>>> later
>>>>>>>>> + version.
>>>>>>>>> +
>>>>>>>>> + GCC is distributed in the hope that it will be useful, but
>>>>>>>>> WITHOUT ANY
>>>>>>>>> + WARRANTY; without even the implied warranty of MERCHANTABILITY or
>>>>>>>>> + FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
>>>>>>>>> License
>>>>>>>>> + for more details.
>>>>>>>>> +
>>>>>>>>> + You should have received a copy of the GNU General Public License
>>>>>>>>> + along with GCC; see the file COPYING3. If not see
>>>>>>>>> + <http://www.gnu.org/licenses/>. */
>>>>>>>>> +
>>>>>>>>> +#define INCLUDE_MEMORY
>>>>>>>>> +#include "config.h"
>>>>>>>>> +#include "system.h"
>>>>>>>>> +#include "coretypes.h"
>>>>>>>>> +#include "backend.h"
>>>>>>>>> +#include "tree.h"
>>>>>>>>> +#include "gimple.h"
>>>>>>>>> +#include "gimple-iterator.h"
>>>>>>>>> +#include "cfganal.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>> +
>>>>>>>>> +/* A mapping from a gimple to a pointer to the move history of it.
>>>>>>>>> */
>>>>>>>>> +static move_history_map_t *move_history_map;
>>>>>>>>> +
>>>>>>>>> +/* Obstack for move history. */
>>>>>>>>> +static struct obstack move_history_obstack;
>>>>>>>>> +
>>>>>>>>> +/* Create a new move history. */
>>>>>>>>> +
>>>>>>>>> +move_history_t
>>>>>>>>> +create_move_history (location_t condition,
>>>>>>>>> + bool is_true_path,
>>>>>>>>> + enum move_reason reason,
>>>>>>>>> + move_history_t prev_move)
>>>>>>>>> +{
>>>>>>>>> + static bool initialized = false;
>>>>>>>>> +
>>>>>>>>> + if (!initialized)
>>>>>>>>> + {
>>>>>>>>> + gcc_obstack_init (&move_history_obstack);
>>>>>>>>> + initialized = true;
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> + move_history_t move_history
>>>>>>>>> + = (move_history_t) obstack_alloc (&move_history_obstack,
>>>>>>>>> + sizeof (struct move_history));
>>>>>>>>> + move_history->condition = condition;
>>>>>>>>> + move_history->is_true_path = is_true_path;
>>>>>>>>> + move_history->reason = reason;
>>>>>>>>> + move_history->prev_move = prev_move;
>>>>>>>>> + return move_history;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Insert the move history for the gimple STMT assuming the linked
>>>>>>>>> list
>>>>>>>>> + of MV_HISTORY does not have duplications. It's the caller's
>>>>>>>>> + responsibility to make sure that the linked list of MV_HISTORY
>>>>>>>>> does
>>>>>>>>> + not have duplications. */
>>>>>>>>> +
>>>>>>>>> +void
>>>>>>>>> +insert_move_history (gimple *stmt, move_history_t mv_history)
>>>>>>>>> +{
>>>>>>>>> + if (!move_history_map)
>>>>>>>>> + move_history_map = new move_history_map_t;
>>>>>>>>> +
>>>>>>>>> + move_history_map->put (stmt, mv_history);
>>>>>>>>> + return;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Get the move history for the gimple STMT, return NULL when there
>>>>>>>>> is
>>>>>>>>> + no associated move history. */
>>>>>>>>> +
>>>>>>>>> +move_history_t
>>>>>>>>> +get_move_history (const gimple *stmt)
>>>>>>>>> +{
>>>>>>>>> + if (!move_history_map)
>>>>>>>>> + return NULL;
>>>>>>>>> +
>>>>>>>>> + if (const move_history_t *mv_history_p = move_history_map->get
>>>>>>>>> (stmt))
>>>>>>>>> + return *mv_history_p;
>>>>>>>>> +
>>>>>>>>> + return NULL;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Remove the move history for STMT. */
>>>>>>>>> +
>>>>>>>>> +void
>>>>>>>>> +remove_move_history (gimple *stmt)
>>>>>>>>> +{
>>>>>>>>> + if (!move_history_map)
>>>>>>>>> + return;
>>>>>>>>> + move_history_map->remove (stmt);
>>>>>>>>> + return;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Check whether the cond_location, is_true_path and reason existed
>>>>>>>>> + * in the OLD_MOVE_HISTORY. */
>>>>>>>>> +
>>>>>>>>> +static bool
>>>>>>>>> +is_move_history_existed (location_t cond_location, bool is_true_path,
>>>>>>>>> + enum move_reason reason,
>>>>>>>>> + move_history_t old_move_history)
>>>>>>>>> +{
>>>>>>>>> + for (move_history_t cur_ch = old_move_history; cur_ch;
>>>>>>>>> + cur_ch = cur_ch->prev_move)
>>>>>>>>> + if ((cur_ch->condition == cond_location)
>>>>>>>>> + && (cur_ch->is_true_path == is_true_path)
>>>>>>>>> + && (cur_ch->reason == reason))
>>>>>>>>> + return true;
>>>>>>>>> +
>>>>>>>>> + return false;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Set move history for the gimple STMT. Return TRUE when a new move
>>>>>>>>> + * history is created and inserted. Otherwise return FALSE. */
>>>>>>>>> +
>>>>>>>>> +bool
>>>>>>>>> +set_move_history (gimple *stmt, location_t cond_location,
>>>>>>>>> + bool is_true_path, enum move_reason reason)
>>>>>>>>> +{
>>>>>>>>> +
>>>>>>>>> + /* First, get the old move history associated with this STMT. */
>>>>>>>>> + move_history_t old_mv_history = get_move_history (stmt);
>>>>>>>>> +
>>>>>>>>> + /* If the current move history is not in the STMT's move history
>>>>>>>>> linked
>>>>>>>>> + list yet, create the new move history, put the old_move_history
>>>>>>>>> as the
>>>>>>>>> + prev_move of it. */
>>>>>>>>> + move_history_t new_mv_history = NULL;
>>>>>>>>> + if (!is_move_history_existed (cond_location, is_true_path,
>>>>>>>>> + reason, old_mv_history))
>>>>>>>>> + new_mv_history
>>>>>>>>> + = create_move_history (cond_location, is_true_path,
>>>>>>>>> + reason, old_mv_history);
>>>>>>>>> +
>>>>>>>>> + /* Insert the move history into the hash map. */
>>>>>>>>> + if (new_mv_history)
>>>>>>>>> + {
>>>>>>>>> + insert_move_history (stmt, new_mv_history);
>>>>>>>>> + return true;
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> + return false;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Reset all state for diagnostic-move-history.cc so that we can
>>>>>>>>> rerun the
>>>>>>>>> + compiler within the same process. For use by toplev::finalize.
>>>>>>>>> */
>>>>>>>>> +
>>>>>>>>> +void
>>>>>>>>> +move_history_finalize (void)
>>>>>>>>> +{
>>>>>>>>> + if (move_history_map)
>>>>>>>>> + {
>>>>>>>>> + delete move_history_map;
>>>>>>>>> + move_history_map = NULL;
>>>>>>>>> + }
>>>>>>>>> + obstack_free (&move_history_obstack, NULL);
>>>>>>>>> + return;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Given an edge ENTRY and whether the new code will be moved to the
>>>>>>>>> + destination of the edge, IS_DISTINATION, return the condition
>>>>>>>>> + statement in the source of the ENTRY if found. Return NULL
>>>>>>>>> otherwise.
>>>>>>>>> +
>>>>>>>>> + When the condition statement is found, setting IS_TRUE_PATH to
>>>>>>>>> true
>>>>>>>>> + if the destination of the edge is on the true path of the
>>>>>>>>> condition.
>>>>>>>>> +
>>>>>>>>> + IS_TRUE_PATH is only valid when the condition statement is found.
>>>>>>>>> +
>>>>>>>>> + source
>>>>>>>>> + | ENTRY
>>>>>>>>> + V
>>>>>>>>> + destination
>>>>>>>>> +
>>>>>>>>> +*/
>>>>>>>>> +
>>>>>>>>> +static gimple *
>>>>>>>>> +get_cond_stmt (edge entry, bool is_destination, bool *is_true_path)
>>>>>>>>> +{
>>>>>>>>> + /* First, get the condition statement in the source of the
>>>>>>>>> + edge ENTRY. */
>>>>>>>>> + basic_block cond_block = entry->src;
>>>>>>>>> + gimple *cond_stmt = NULL;
>>>>>>>>> + gimple_stmt_iterator gsi;
>>>>>>>>> + *is_true_path = false;
>>>>>>>>> +
>>>>>>>>> + /* if the cond_block ends with a conditional statement, get it. */
>>>>>>>>> + while (!cond_stmt && cond_block)
>>>>>>>>> + {
>>>>>>>>> + gsi = gsi_last_bb (cond_block);
>>>>>>>>> + if (!gsi_end_p (gsi)
>>>>>>>>> + && gsi_stmt (gsi)
>>>>>>>>> + && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND))
>>>>>>>>> + cond_stmt = gsi_stmt (gsi);
>>>>>>>>> + /* If there is no cond_stmt in the cond_block, search the
>>>>>>>>> single_pred
>>>>>>>>> + of it. */
>>>>>>>>> + if (!cond_stmt && single_pred_p (cond_block))
>>>>>>>>> + {
>>>>>>>>> + basic_block prev_cond_block = cond_block;
>>>>>>>>> + cond_block = single_pred (cond_block);
>>>>>>>>> + entry = find_edge (cond_block, prev_cond_block);
>>>>>>>>> + }
>>>>>>>>> + else
>>>>>>>>> + break;
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> + bool is_branch_taken = (cond_stmt && (BRANCH_EDGE (cond_block) ==
>>>>>>>>> entry));
>>>>>>>>> + *is_true_path = !(is_branch_taken ^ is_destination);
>>>>>>>>> +
>>>>>>>>> + return cond_stmt;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Set move history to the stmt based on the edge ENTRY and whether
>>>>>>>>> this stmt
>>>>>>>>> + will be in the destination of the ENTRY.
>>>>>>>>> + The REASON indicates what kind of transformation contributing to
>>>>>>>>> the
>>>>>>>>> + statment movement. Return TRUE when the move history has been set
>>>>>>>>> + successfully. */
>>>>>>>>> +
>>>>>>>>> +bool
>>>>>>>>> +set_move_history_to_stmt (gimple *stmt, edge entry,
>>>>>>>>> + bool is_destination, enum move_reason
>>>>>>>>> reason)
>>>>>>>>> +{
>>>>>>>>> + bool is_true_path = false;
>>>>>>>>> + gimple *cond_stmt = get_cond_stmt (entry, is_destination,
>>>>>>>>> &is_true_path);
>>>>>>>>> +
>>>>>>>>> + if (!cond_stmt)
>>>>>>>>> + return false;
>>>>>>>>> +
>>>>>>>>> + set_move_history (stmt, gimple_location (cond_stmt),
>>>>>>>>> + is_true_path, reason);
>>>>>>>>> + return true;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> +/* Set move history to all the stmts in the basic block BB based on
>>>>>>>>> + the edge ENTRY and whether this basic block will be the
>>>>>>>>> destination
>>>>>>>>> + of the ENTRY.
>>>>>>>>> + The REASON indicates what kind of transformation contributing to
>>>>>>>>> the
>>>>>>>>> + statement move. Return TRUE when the move history has been set
>>>>>>>>> + successfully. */
>>>>>>>>> +
>>>>>>>>> +bool
>>>>>>>>> +set_move_history_to_stmts_in_bb (basic_block bb, edge entry,
>>>>>>>>> + bool is_destination,
>>>>>>>>> + enum move_reason reason)
>>>>>>>>> +{
>>>>>>>>> + bool is_true_path = false;
>>>>>>>>> + gimple_stmt_iterator gsi;
>>>>>>>>> + gimple *cond_stmt = get_cond_stmt (entry, is_destination,
>>>>>>>>> &is_true_path);
>>>>>>>>> +
>>>>>>>>> + if (!cond_stmt)
>>>>>>>>> + return false;
>>>>>>>>> + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
>>>>>>>>> + set_move_history (gsi_stmt (gsi), gimple_location (cond_stmt),
>>>>>>>>> + is_true_path, reason);
>>>>>>>>> +
>>>>>>>>> + return true;
>>>>>>>>> +}
>>>>>>>>> diff --git a/gcc/diagnostic-move-history.h
>>>>>>>>> b/gcc/diagnostic-move-history.h
>>>>>>>>> new file mode 100644
>>>>>>>>> index 00000000000..9a58766d544
>>>>>>>>> --- /dev/null
>>>>>>>>> +++ b/gcc/diagnostic-move-history.h
>>>>>>>>> @@ -0,0 +1,92 @@
>>>>>>>>> +/* Move history associated with a gimple statement to record its
>>>>>>>>> history
>>>>>>>>> + of movement due to different transformations.
>>>>>>>>> + The move history will be used to construct events for later
>>>>>>>>> diagnostic.
>>>>>>>>> +
>>>>>>>>> + Copyright (C) 2024 Free Software Foundation, Inc.
>>>>>>>>> + Contributed by Qing Zhao <qing.z...@oracle.com>
>>>>>>>>> +
>>>>>>>>> + This file is part of GCC.
>>>>>>>>> +
>>>>>>>>> + GCC is free software; you can redistribute it and/or modify it
>>>>>>>>> under
>>>>>>>>> + the terms of the GNU General Public License as published by the
>>>>>>>>> Free
>>>>>>>>> + Software Foundation; either version 3, or (at your option) any
>>>>>>>>> later
>>>>>>>>> + version.
>>>>>>>>> +
>>>>>>>>> + GCC is distributed in the hope that it will be useful, but
>>>>>>>>> WITHOUT ANY
>>>>>>>>> + WARRANTY; without even the implied warranty of MERCHANTABILITY or
>>>>>>>>> + FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
>>>>>>>>> License
>>>>>>>>> + for more details.
>>>>>>>>> +
>>>>>>>>> + You should have received a copy of the GNU General Public License
>>>>>>>>> + along with GCC; see the file COPYING3. If not see
>>>>>>>>> + <http://www.gnu.org/licenses/>. */
>>>>>>>>> +
>>>>>>>>> +#ifndef DIAGNOSTIC_MOVE_HISTORY_H
>>>>>>>>> +#define DIAGNOSTIC_MOVE_HISTORY_H
>>>>>>>>> +
>>>>>>>>> +#include "hash-map.h"
>>>>>>>>> +#include "line-map.h"
>>>>>>>>> +
>>>>>>>>> +/* An enum for the reason why this move is made. Right now, there
>>>>>>>>> are
>>>>>>>>> + three reasons, we can add more if needed. */
>>>>>>>>> +enum move_reason {
>>>>>>>>> + COPY_BY_THREAD_JUMP,
>>>>>>>>> + COPY_BY_ISOLATE_PATH,
>>>>>>>>> + MOVE_BY_SINK,
>>>>>>>>> + COPY_BY_MAX
>>>>>>>>> +};
>>>>>>>>> +
>>>>>>>>> +/* This data structure records the information when a statement is
>>>>>>>>> + moved along control flow graph during different transformations.
>>>>>>>>> + Such information will be used by the later diagnostic messages
>>>>>>>>> + to report more contexts of the warnings or errors. */
>>>>>>>>> +struct move_history {
>>>>>>>>> + /* The location of the condition statement that triggered the code
>>>>>>>>> + movement. */
>>>>>>>>> + location_t condition;
>>>>>>>>> +
>>>>>>>>> + /* Whether this move is on the TRUE path of the condition. */
>>>>>>>>> + bool is_true_path;
>>>>>>>>> +
>>>>>>>>> + /* The reason for the code movement. */
>>>>>>>>> + enum move_reason reason;
>>>>>>>>> +
>>>>>>>>> + /* This statement itself might be a previous code movement. */
>>>>>>>>> + struct move_history *prev_move;
>>>>>>>>> +};
>>>>>>>>> +
>>>>>>>>> +typedef struct move_history *move_history_t;
>>>>>>>>> +
>>>>>>>>> +/* Create a new move history. */
>>>>>>>>> +extern move_history_t create_move_history (location_t, bool,
>>>>>>>>> + enum move_reason,
>>>>>>>>> move_history_t);
>>>>>>>>> +
>>>>>>>>> +typedef hash_map<const gimple *, move_history_t> move_history_map_t;
>>>>>>>>> +
>>>>>>>>> +/* Get the move history for the gimple STMT, return NULL when there
>>>>>>>>> is
>>>>>>>>> + no associated move history. */
>>>>>>>>> +extern move_history_t get_move_history (const gimple *);
>>>>>>>>> +
>>>>>>>>> +/* Remove the move history for STMT from the move_history_map. */
>>>>>>>>> +extern void remove_move_history (gimple *);
>>>>>>>>> +
>>>>>>>>> +/* Set move history for the gimple STMT. */
>>>>>>>>> +extern bool set_move_history (gimple *, location_t,
>>>>>>>>> + bool, enum move_reason);
>>>>>>>>> +
>>>>>>>>> +/* Reset all state for diagnostic-move-history.cc so that we can
>>>>>>>>> rerun the
>>>>>>>>> + compiler within the same process. For use by toplev::finalize.
>>>>>>>>> */
>>>>>>>>> +extern void move_history_finalize (void);
>>>>>>>>> +
>>>>>>>>> +/* Set move history to the stmt based on the edge ENTRY and whether
>>>>>>>>> this stmt
>>>>>>>>> + will be in the destination of the ENTRY. */
>>>>>>>>> +extern bool set_move_history_to_stmt (gimple *, edge,
>>>>>>>>> + bool, enum move_reason);
>>>>>>>>> +
>>>>>>>>> +/* Set move history to all the stmts in the basic block based on
>>>>>>>>> + the entry edge and whether this basic block will be the
>>>>>>>>> destination
>>>>>>>>> + of the entry edge. */
>>>>>>>>> +extern bool set_move_history_to_stmts_in_bb (basic_block, edge,
>>>>>>>>> + bool, enum move_reason);
>>>>>>>>> +
>>>>>>>>> +#endif // DIAGNOSTIC_MOVE_HISTORY_H
>>>>>>>>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>>>>>>>>> index ee7180110e1..ca04f35d6a1 100644
>>>>>>>>> --- a/gcc/doc/invoke.texi
>>>>>>>>> +++ b/gcc/doc/invoke.texi
>>>>>>>>> @@ -332,6 +332,7 @@ Objective-C and Objective-C++ Dialects}.
>>>>>>>>> -fdiagnostics-column-origin=@var{origin}
>>>>>>>>> -fdiagnostics-escape-format=@r{[}unicode@r{|}bytes@r{]}
>>>>>>>>> -fdiagnostics-text-art-charset=@r{[}none@r{|}ascii@r{|}unicode@r{|}emoji@r{]}}
>>>>>>>>> +-fdiagnostics-details
>>>>>>>>>
>>>>>>>>> @item Warning Options
>>>>>>>>> @xref{Warning Options,,Options to Request or Suppress Warnings}.
>>>>>>>>> @@ -5687,6 +5688,16 @@ left margin.
>>>>>>>>> This option controls the minimum width of the left margin printed by
>>>>>>>>> @option{-fdiagnostics-show-line-numbers}. It defaults to 6.
>>>>>>>>>
>>>>>>>>> +@opindex fdiagnostics-details
>>>>>>>>> +@item -fdiagnostics-details
>>>>>>>>> +With this option, the compiler collects more context information for
>>>>>>>>> +diagnostics and emits them to the users to provide more hints on how
>>>>>>>>> +the diagnostics come from, at the cost of a slightly slower
>>>>>>>>> compilation.
>>>>>>>>> +Currently, The list of the impacted warning options includes:
>>>>>>>>> +@option{-Warray-bounds}, @option{-Wstringop-overflow},
>>>>>>>>> +@option{-Wstringop-overread}, and @option{-Wstringop-truncation}.
>>>>>>>>> +More warning options might be added to this list in future releases.
>>>>>>>>> +
>>>>>>>>> @opindex fdiagnostics-parseable-fixits
>>>>>>>>> @item -fdiagnostics-parseable-fixits
>>>>>>>>> Emit fix-it hints in a machine-parseable format, suitable for
>>>>>>>>> consumption
>>>>>>>>> diff --git a/gcc/gimple-iterator.cc b/gcc/gimple-iterator.cc
>>>>>>>>> index 3af672bf0b9..f1d7ca9c78e 100644
>>>>>>>>> --- a/gcc/gimple-iterator.cc
>>>>>>>>> +++ b/gcc/gimple-iterator.cc
>>>>>>>>> @@ -33,6 +33,7 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>> #include "tree-ssa.h"
>>>>>>>>> #include "value-prof.h"
>>>>>>>>> #include "gimplify.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /* Mark the statement STMT as modified, and update it. */
>>>>>>>>> @@ -581,6 +582,8 @@ gsi_remove (gimple_stmt_iterator *i, bool
>>>>>>>>> remove_permanently)
>>>>>>>>> cfun->debug_marker_count--;
>>>>>>>>> require_eh_edge_purge = remove_stmt_from_eh_lp (stmt);
>>>>>>>>> gimple_remove_stmt_histograms (cfun, stmt);
>>>>>>>>> + if (get_move_history (stmt) != NULL)
>>>>>>>>> + remove_move_history (stmt);
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> /* Update the iterator and re-wire the links in I->SEQ. */
>>>>>>>>> diff --git a/gcc/gimple-pretty-print.cc b/gcc/gimple-pretty-print.cc
>>>>>>>>> index 4e20b4cc371..811164565bb 100644
>>>>>>>>> --- a/gcc/gimple-pretty-print.cc
>>>>>>>>> +++ b/gcc/gimple-pretty-print.cc
>>>>>>>>> @@ -44,6 +44,7 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>> #include "asan.h"
>>>>>>>>> #include "cfgloop.h"
>>>>>>>>> #include "gimple-range.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>>
>>>>>>>>> /* Disable warnings about quoting issues in the pp_xxx calls below
>>>>>>>>> that (intentionally) don't follow GCC diagnostic conventions. */
>>>>>>>>> @@ -2734,6 +2735,9 @@ pp_gimple_stmt_1 (pretty_printer *pp, const
>>>>>>>>> gimple *gs, int spc,
>>>>>>>>> && (flags & TDF_ALIAS))
>>>>>>>>> dump_ssaname_info (pp, gimple_get_lhs (gs), spc);
>>>>>>>>>
>>>>>>>>> + if (get_move_history (gs))
>>>>>>>>> + pp_printf (pp, "[MV_H] ");
>>>>>>>>> +
>>>>>>>>> switch (gimple_code (gs))
>>>>>>>>> {
>>>>>>>>> case GIMPLE_ASM:
>>>>>>>>> diff --git a/gcc/gimple-ssa-isolate-paths.cc
>>>>>>>>> b/gcc/gimple-ssa-isolate-paths.cc
>>>>>>>>> index ca1daf1d168..14c86590b17 100644
>>>>>>>>> --- a/gcc/gimple-ssa-isolate-paths.cc
>>>>>>>>> +++ b/gcc/gimple-ssa-isolate-paths.cc
>>>>>>>>> @@ -37,6 +37,7 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>> #include "tree-cfg.h"
>>>>>>>>> #include "cfganal.h"
>>>>>>>>> #include "intl.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> static bool cfg_altered;
>>>>>>>>> @@ -170,6 +171,16 @@ isolate_path (basic_block bb, basic_block
>>>>>>>>> duplicate,
>>>>>>>>> }
>>>>>>>>> bb->count -= count;
>>>>>>>>>
>>>>>>>>> + /* Set the move history for all the stmts in both original and
>>>>>>>>> copied
>>>>>>>>> + basic blocks. The duplicated block will be the destination of
>>>>>>>>> the
>>>>>>>>> + incoming edge. */
>>>>>>>>> + if (flag_diagnostics_details)
>>>>>>>>> + {
>>>>>>>>> + set_move_history_to_stmts_in_bb (bb, e, false,
>>>>>>>>> COPY_BY_ISOLATE_PATH);
>>>>>>>>> + set_move_history_to_stmts_in_bb (duplicate, e,
>>>>>>>>> + true, COPY_BY_ISOLATE_PATH);
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> /* Complete the isolation step by redirecting E to reach DUPLICATE.
>>>>>>>>> */
>>>>>>>>> e2 = redirect_edge_and_branch (e, duplicate);
>>>>>>>>> if (e2)
>>>>>>>>> diff --git a/gcc/testsuite/gcc.dg/pr117375.c
>>>>>>>>> b/gcc/testsuite/gcc.dg/pr117375.c
>>>>>>>>> new file mode 100644
>>>>>>>>> index 00000000000..beb685afc3b
>>>>>>>>> --- /dev/null
>>>>>>>>> +++ b/gcc/testsuite/gcc.dg/pr117375.c
>>>>>>>>> @@ -0,0 +1,13 @@
>>>>>>>>> +/* PR middle-end/117375 ICE with -fdiagnostics-details patch in sink
>>>>>>>>> pass. */
>>>>>>>>> +/* { dg-do compile }
>>>>>>>>> + { dg-options "-O2 -Wall -fdiagnostics-details" } */
>>>>>>>>> +
>>>>>>>>> +int st, st_0;
>>>>>>>>> +int nbFilledBytes, max;
>>>>>>>>> +void ec_enc_shrink();
>>>>>>>>> +void max_allowed() {
>>>>>>>>> + int nbAvailableBytes = nbFilledBytes;
>>>>>>>>> + if (st && st_0)
>>>>>>>>> + if (max < nbAvailableBytes)
>>>>>>>>> + ec_enc_shrink();
>>>>>>>>> +}
>>>>>>>>> diff --git a/gcc/toplev.cc b/gcc/toplev.cc
>>>>>>>>> index 7e457b5168b..7652c222676 100644
>>>>>>>>> --- a/gcc/toplev.cc
>>>>>>>>> +++ b/gcc/toplev.cc
>>>>>>>>> @@ -42,6 +42,7 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>> #include "coverage.h"
>>>>>>>>> #include "diagnostic.h"
>>>>>>>>> #include "pretty-print-urlifier.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>> #include "varasm.h"
>>>>>>>>> #include "tree-inline.h"
>>>>>>>>> #include "realmpfr.h" /* For GMP/MPFR/MPC versions, in
>>>>>>>>> print_version. */
>>>>>>>>> @@ -2436,6 +2437,8 @@ toplev::finalize (void)
>>>>>>>>> reginfo_cc_finalize ();
>>>>>>>>> varasm_cc_finalize ();
>>>>>>>>>
>>>>>>>>> + move_history_finalize ();
>>>>>>>>> +
>>>>>>>>> /* save_decoded_options uses opts_obstack, so these must
>>>>>>>>> be cleaned up together. */
>>>>>>>>> obstack_free (&opts_obstack, NULL);
>>>>>>>>> diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc
>>>>>>>>> index 959e0d5c6be..0b3441e894c 100644
>>>>>>>>> --- a/gcc/tree-ssa-sink.cc
>>>>>>>>> +++ b/gcc/tree-ssa-sink.cc
>>>>>>>>> @@ -37,6 +37,7 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>> #include "tree-eh.h"
>>>>>>>>> #include "tree-ssa-live.h"
>>>>>>>>> #include "tree-dfa.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>>
>>>>>>>>> /* TODO:
>>>>>>>>> 1. Sinking store only using scalar promotion (IE without moving the
>>>>>>>>> RHS):
>>>>>>>>> @@ -655,6 +656,49 @@ sink_common_stores_to_bb (basic_block bb)
>>>>>>>>> return todo;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> +/* Get the edge chain from FROM_BB to TO_BB, FROM_BB dominates TO_BB.
>>>>>>>>> + B2
>>>>>>>>> + / \
>>>>>>>>> + V \
>>>>>>>>> + B3 \
>>>>>>>>> + / \ \
>>>>>>>>> + V \---->V
>>>>>>>>> + B4 B7
>>>>>>>>> +
>>>>>>>>> + In the above CFG, FROM_BB is B2, TO_BB is B4. This routine
>>>>>>>>> + will locate two edges, B2->B3, and B3->B4 and return a vector
>>>>>>>>> + with these two edges.
>>>>>>>>> + This routine will return an empty vector if the control flow
>>>>>>>>> + edge chain from FROM_BB to TO_BB is too complicate. */
>>>>>>>>> +
>>>>>>>>> +static auto_vec<edge>
>>>>>>>>> +get_edge_chain (basic_block from_bb, basic_block to_bb)
>>>>>>>>> +{
>>>>>>>>> + auto_vec<edge> rev_edge_chain, edge_chain;
>>>>>>>>> + basic_block imm_dom_bb;
>>>>>>>>> + edge e;
>>>>>>>>> + unsigned int i;
>>>>>>>>> + /* Backtracing from TO_BB to FROM_BB through the dominator tree.
>>>>>>>>> */
>>>>>>>>> + do
>>>>>>>>> + {
>>>>>>>>> + imm_dom_bb = get_immediate_dominator (CDI_DOMINATORS, to_bb);
>>>>>>>>> + if (!imm_dom_bb)
>>>>>>>>> + return edge_chain;
>>>>>>>>> + e = find_edge (imm_dom_bb, to_bb);
>>>>>>>>> + if (!e)
>>>>>>>>> + return edge_chain;
>>>>>>>>> + gcc_assert (e);
>>>>>>>>> + rev_edge_chain.safe_push (e);
>>>>>>>>> + to_bb = imm_dom_bb;
>>>>>>>>> + }
>>>>>>>>> + while (imm_dom_bb != from_bb);
>>>>>>>>> +
>>>>>>>>> + /* The order of the edges need to be reverted. */
>>>>>>>>> + FOR_EACH_VEC_ELT_REVERSE (rev_edge_chain, i, e)
>>>>>>>>> + edge_chain.safe_push (e);
>>>>>>>>> + return edge_chain;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> /* Perform code sinking on BB */
>>>>>>>>>
>>>>>>>>> static unsigned
>>>>>>>>> @@ -712,6 +756,19 @@ sink_code_in_bb (basic_block bb,
>>>>>>>>> virtual_operand_live &vop_live)
>>>>>>>>> bb->index, (gsi_bb (togsi))->index);
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> + /* Set the move history for the stmt that is sinked from BB to
>>>>>>>>> + gsi_bb (togsi). This stmt is on the path from BB to
>>>>>>>>> + gsi_bb (togsi). */
>>>>>>>>> + if (flag_diagnostics_details)
>>>>>>>>> + {
>>>>>>>>> + /* BB might not be the immediate predecessor of gsi_bb
>>>>>>>>> (togsi),
>>>>>>>>> + get the edge chain from BB to gsi_bb (togsi). */
>>>>>>>>> + auto_vec<edge> edge_chain = get_edge_chain (bb, gsi_bb
>>>>>>>>> (togsi));
>>>>>>>>> +
>>>>>>>>> + for (edge entry : edge_chain)
>>>>>>>>> + set_move_history_to_stmt (stmt, entry, true,
>>>>>>>>> MOVE_BY_SINK);
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> /* Update virtual operands of statements in the path we
>>>>>>>>> do not sink to. */
>>>>>>>>> if (gimple_vdef (stmt))
>>>>>>>>> diff --git a/gcc/tree-ssa-threadupdate.cc
>>>>>>>>> b/gcc/tree-ssa-threadupdate.cc
>>>>>>>>> index 4e5c7566857..789ca1d9422 100644
>>>>>>>>> --- a/gcc/tree-ssa-threadupdate.cc
>>>>>>>>> +++ b/gcc/tree-ssa-threadupdate.cc
>>>>>>>>> @@ -36,6 +36,7 @@ along with GCC; see the file COPYING3. If not see
>>>>>>>>> #include "tree-cfg.h"
>>>>>>>>> #include "tree-vectorizer.h"
>>>>>>>>> #include "tree-pass.h"
>>>>>>>>> +#include "diagnostic-move-history.h"
>>>>>>>>>
>>>>>>>>> /* Given a block B, update the CFG and SSA graph to reflect
>>>>>>>>> redirecting
>>>>>>>>> one or more in-edges to B to instead reach the destination of an
>>>>>>>>> @@ -1341,6 +1342,17 @@ ssa_redirect_edges (struct redirection_data
>>>>>>>>> **slot,
>>>>>>>>> {
>>>>>>>>> edge e2;
>>>>>>>>>
>>>>>>>>> + /* Set the move history for all the stmts in both original
>>>>>>>>> and copied
>>>>>>>>> + basic blocks. The duplicated block will be the
>>>>>>>>> destination of the
>>>>>>>>> + incoming edge. */
>>>>>>>>> + if (flag_diagnostics_details)
>>>>>>>>> + {
>>>>>>>>> + set_move_history_to_stmts_in_bb (e->dest, e, false,
>>>>>>>>> + COPY_BY_THREAD_JUMP);
>>>>>>>>> + set_move_history_to_stmts_in_bb (rd->dup_blocks[0], e,
>>>>>>>>> + true,
>>>>>>>>> COPY_BY_THREAD_JUMP);
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> if (dump_file && (dump_flags & TDF_DETAILS))
>>>>>>>>> fprintf (dump_file, " Threaded jump %d --> %d to %d\n",
>>>>>>>>> e->src->index, e->dest->index,
>>>>>>>>> rd->dup_blocks[0]->index);
>>>>>>>>> @@ -2419,6 +2431,19 @@ back_jt_path_registry::duplicate_thread_path
>>>>>>>>> (edge entry,
>>>>>>>>> copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
>>>>>>>>> split_edge_bb_loc (entry), false);
>>>>>>>>>
>>>>>>>>> + /* Set the move history for all the stmts in both original and
>>>>>>>>> copied
>>>>>>>>> + basic blocks. The copied regions will be the destination of the
>>>>>>>>> + entry edge. */
>>>>>>>>> + for (i = 0; i < n_region; i++)
>>>>>>>>> + if (flag_diagnostics_details)
>>>>>>>>> + {
>>>>>>>>> + set_move_history_to_stmts_in_bb (region[i], entry, false,
>>>>>>>>> + COPY_BY_THREAD_JUMP);
>>>>>>>>> + set_move_history_to_stmts_in_bb (region_copy[i], entry,
>>>>>>>>> + true, COPY_BY_THREAD_JUMP);
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> +
>>>>>>>>> /* Fix up: copy_bbs redirects all edges pointing to copied blocks.
>>>>>>>>> The
>>>>>>>>> following code ensures that all the edges exiting the jump-thread
>>>>>>>>> path are
>>>>>>>>> redirected back to the original code: these edges are exceptions
>>>>>>>>> --
>>>>>>>>> 2.31.1
