On Tue, Nov 3, 2015 at 9:47 PM, Kenneth Graunke <kenn...@whitecape.org> wrote:
> On Wednesday, October 21, 2015 03:58:14 PM Matt Turner wrote:
>> Will allow annotations to contain error messages (indicating an
>> instruction violates a rule for instance) that are printed after the
>> disassembly of the block.
>> ---
>> src/mesa/drivers/dri/i965/intel_asm_annotation.c | 60
>> ++++++++++++++++++++++++
>> src/mesa/drivers/dri/i965/intel_asm_annotation.h | 7 +++
>> 2 files changed, 67 insertions(+)
>>
>> diff --git a/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> b/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> index 58830db..eaee386 100644
>> --- a/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> +++ b/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> @@ -69,6 +69,10 @@ dump_assembly(void *assembly, int num_annotations, struct
>> annotation *annotation
>>
>> brw_disassemble(devinfo, assembly, start_offset, end_offset, stderr);
>>
>> + if (annotation[i].error) {
>> + fputs(annotation[i].error, stderr);
>> + }
>> +
>> if (annotation[i].block_end) {
>> fprintf(stderr, " END B%d", annotation[i].block_end->num);
>> foreach_list_typed(struct bblock_link, successor_link, link,
>> @@ -152,3 +156,59 @@ annotation_finalize(struct annotation_info *annotation,
>> }
>> annotation->ann[annotation->ann_count].offset = next_inst_offset;
>> }
>> +
>> +void
>> +annotation_insert_error(struct annotation_info *annotation, unsigned offset,
>> + const char *error)
>> +{
>> + struct annotation *ann = NULL;
>> +
>> + if (!annotation->ann_count)
>> + return;
>
> If I'm reading this correctly, it means that we won't report any errors
> if there are no annotations. Shouldn't we instead insert a new
> annotation in this case? Something like:
ann_count is nonzero iff we're printing the disassembly. ann_count
counts the number of "annotation blocks", not the number of
source-level/IR annotations.
And if we're not printing the disassembly, then yeah, we won't print
any errors... because where and how would we print them?
> if (annotation->ann_count == 0) {
> struct annotation *ann = &annotation->ann[0];
> annotation->ann_count++;
> ann->offset = 0;
> ann->block_start = NULL;
> ann->block_end = NULL;
> ann->ir = NULL;
> ann->annotation = NULL;
> ann->error = ralloc_strdup(annotation->mem_ctx, error);
> return;
> }
>
>> +
>> + /* We may have to split an annotation, so ensure we have enough space
>> + * allocated for that case up front.
>> + */
>> + if (annotation->ann_size <= annotation->ann_count) {
>> + int old_size = annotation->ann_size;
>> + annotation->ann_size = MAX2(1024, annotation->ann_size * 2);
>> + annotation->ann = reralloc(annotation->mem_ctx, annotation->ann,
>> + struct annotation, annotation->ann_size);
>> + if (!annotation->ann)
>> + return;
>> +
>> + memset(annotation->ann + old_size, 0,
>> + (annotation->ann_size - old_size) * sizeof(struct annotation));
>> + }
>
> I agree with Topi, let's use a helper function, such as:
>
> /**
> * Make sure the annotation->ann[] array has room for one more element.
> */
> static void
> grow_annotation_array(struct annotation_info *annotation)
> {
> ...
> }
>
>> +
>> + for (int i = 0; i <= annotation->ann_count; i++) {
>
> Tricky...you're relying on the fact that annotation_finalize() has made
> ann[ann_count] exist and have an offset equal to the end of the program.
> So, there's a sentinel annotation of sorts, which makes <= okay (as
> opposed to the obvious choice of <), and also guarantees that you'll
> actually find an element whose offset is larger.
You want to find the one that includes the instruction at <offset>, so
you skip things that are "not greater", i.e. <=, than the offset.
> But this isn't safe when i = 0, as cur will be out of bounds...
I don't think so. The code as-is might be tricky, but I think it's correct --
>> + if (annotation->ann[i].offset <= offset)
>> + continue;
For i = 0, annotation->ann[i].offset is always 0 (or the start of the
SIMD16 program, I suppose). In both cases, <offset> cannot be less
than that value. Knowing that, maybe the loop should just begin at i =
1.
At least, I think. It's been more than two weeks since I've really
thought about this :(
>> +
>> + struct annotation *cur = &annotation->ann[i - 1];
>> + struct annotation *next = &annotation->ann[i];
>
> Okay, having "cur" be the (i - 1)th element and "next" be the ith
> element is just mean :( That's not what those mean.
>
>> + ann = cur;
>> +
>> + if (offset + sizeof(brw_inst) != next->offset) {
>> + memmove(next, cur,
>> + (annotation->ann_count - i + 2) * sizeof(struct
>> annotation));
>> + cur->error = NULL;
>> + cur->error_length = 0;
>> + cur->block_end = NULL;
>> + next->offset = offset + sizeof(brw_inst);
>> + next->block_start = NULL;
>> + annotation->ann_count++;
>> + }
>> + break;
>> + }
>
> I think this would be easier to follow:
>
> /* We want to insert the error comment /after/ the instruction. */
> unsigned insertion_point = offset + sizeof(brw_inst);
>
> /* Note that annotation_finalize() has placed a sentinel annotation
> * at annotation->ann[annotation->ann_count] with an offset that is
> * the end of the program. So we're guaranteed to find an entry.
> */
> for (int i = 0; i <= annotation->ann_count; i++) {
> struct annotation *cur = &annotation->ann[i];
>
> /* If the current annotation begins exactly where we want to
> * insert the error, we can simply use it.
> */
> if (cur->offset == insertion_point) {
> ann = cur;
> break;
> }
>
> /* If the current annotation starts beyond our insertion point,
> * stop. Insert a new annotation before cur, shifting the rest
> * of the array over to make room.
> */
> if (cur->offset > insertion_point) {
> cur->block_start = NULL; // XXX: why?
I have no idea why... my code didn't do this :)
The idea in setting block_start/end to null is that when splitting the
annotation block, the second one can't start a basic block and the
first can't end a basic block.
> memmove(cur + 1, cur,
> (annotation->ann_count - i + 2) * sizeof(struct annotation));
> ann = cur;
> ann->error = NULL;
> ann->error_length = 0;
> ann->block_end = NULL;
> ann->offset = insertion_point;
> annotation->ann_count++;
> break;
> }
> }
>
> Actually, if you make annotation_finalize() add the sentinel even when
> ann_count == 0, you should be able to safely use this code without
> needing to special case ann_count == 0 up above. Which would be nice.
I think there's some confusion about when this code is used. To
confirm, it's only used when we're disassembling the program. If we're
disassembling the program, ann_count cannot be zero.
Does this make sense, or have I misunderstood something?
>> +
>> + assume(ann != NULL);
>> +
>> + ralloc_asprintf_rewrite_tail(&ann->error, &ann->error_length, error);
>
> Using asprintf with an ordinary (non-format) string is wrong...it'll
> interpret % characters...and you haven't given it any arguments. You
> could do (..., "%s", error)...but this just seems like the wrong fit.
Oh, yeah. I had been using ralloc_vasprintf_rewrite_tail with vaargs
but then realized that I was just passing a single string in, so I
changed it to this shortly before sending.
>
> I would just do:
>
> if (ann->error)
> ralloc_strcat(&ann->error, error);
> else
> ann->error = ralloc_strdup(annotation->mem_ctx, error);
>
> You can drop the FIXME code below, as you'll be using the right memory
> context. You can also drop the error_length field, as it's not needed.
>
> Sure, you gain extra strlen() calls when appending, but it's not worth
> optimizing...this is debug-only code...error strings aren't that
> long...and hopefully you don't have a cacophony of errors in the first
> place...
>
>> +
>> + /* FIXME: ralloc_vasprintf_rewrite_tail() allocates memory out of the
>> + * null context. We have to reparent the it if we want it to be freed
>> + * with the rest of the annotation context.
>> + */
>> + ralloc_steal(annotation->mem_ctx, ann->error);
>> +}
>> diff --git a/src/mesa/drivers/dri/i965/intel_asm_annotation.h
>> b/src/mesa/drivers/dri/i965/intel_asm_annotation.h
>> index 6c72326..662a4b4 100644
>> --- a/src/mesa/drivers/dri/i965/intel_asm_annotation.h
>> +++ b/src/mesa/drivers/dri/i965/intel_asm_annotation.h
>> @@ -37,6 +37,9 @@ struct cfg_t;
>> struct annotation {
>> int offset;
>>
>> + size_t error_length;
>> + char *error;
>> +
>> /* Pointers to the basic block in the CFG if the instruction group starts
>> * or ends a basic block.
>> */
>> @@ -69,6 +72,10 @@ annotate(const struct brw_device_info *devinfo,
>> void
>> annotation_finalize(struct annotation_info *annotation, unsigned offset);
>>
>> +void
>> +annotation_insert_error(struct annotation_info *annotation, unsigned offset,
>> + const char *error);
>> +
>> #ifdef __cplusplus
>> } /* extern "C" */
>> #endif
>>
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