Changes

[mlir][linalg][bufferize][NFC] Collect equivalent FuncOp BBArgs in PostAnalysisStep

Collect equivalent BBArgs right after the equivalence analysis of the FuncOp and before bufferizing. This is in preparation of decoupling bufferization from aliasInfo.

Also gather equivalence info for CallOps, which was missing in the
previous commit.

Differential Revision: https://reviews.llvm.org/D114847

[mlir] Add default implementations for methods in `TilingInterface`.

Adding the default implementation of `getLoopIteratorTypes` and
`getLoopBounds` allows ExternalModels to override these methods.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D115101

[WebAssembly] Implementation of intrinsic for ref.null and HeapType removal

This patch implements the intrinsic for ref.null.
In the process of implementing int_wasm_ref_null_func() and
int_wasm_ref_null_extern() intrinsics, it removes the redundant
HeapType.

This also causes the textual assembler syntax for ref.null to
change. Instead of receiving an argument: `func` or `extern`, the
instruction mnemonic is either ref.null_func or ref.null_extern,
without the need for a further operand.

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D114979

[mlir][linalg][bufferize] Remove buffer equivalence from bufferize

Remove all function calls related to buffer equivalence from bufferize implementations.

Add a new PostAnalysisStep for scf.for that ensures that yielded values are equivalent to the corresponding BBArgs. (This was previously checked in `bufferize`.) This will be relaxed in a subsequent commit.

Note: This commit changes two test cases. These were broken by design
and should not have passed. With the new scf.for PostAnalysisStep, this
bug was fixed.

Differential Revision: https://reviews.llvm.org/D114927

[analyzer] Ignore flex generated files

Some projects [1,2,3] have flex-generated files besides bison-generated
ones.
Unfortunately, the comment `"/* A lexical scanner generated by flex */"`
generated by the tools is not necessarily at the beginning of the file,
thus we need to quickly skim through the file for this needle string.

Luckily, StringRef can do this operation in an efficient way.

That being said, now the bison comment is not required to be at the very
beginning of the file. This allows us to detect a couple more cases
[4,5,6].

Alternatively, we could say that we only allow whitespace characters
before matching the bison/flex header comment. That would prevent the
(probably) unnecessary string search in the buffer. However, I could not
verify that these tools would actually respect this assumption.

Additionally to this, e.g. the Twin project [1] has other non-whitespace
characters (some preprocessor directives) before the flex-generated
header comment. So the heuristic in the previous paragraph won't work
with that.
Thus, I would advocate the current implementation.

According to my measurement, this patch won't introduce measurable
performance degradation, even though we will do 2 linear scans.

I introduce the ignore-bison-generated-files and
ignore-flex-generated-files to disable skipping these files.
Both of these options are true by default.

[1]: https://github.com/cosmos72/twin/blob/master/server/rcparse_lex.cpp#L7
[2]: https://github.com/marcauresoar/make-examples/blob/22362cdcf9dd7c597b5049ce7f176621e2e9ac7a/sandbox/count-words/lexer.c#L6
[3]: https://github.com/vladcmanea/2nd-faculty-year-Formal-Languages---Automata-assignments/blob/11abdf64629d9eb741438ba69f04636769d5a374/lab1/lex.yy.c#L6

[4]: https://github.com/KritikaChoudhary/System-Software-Lab/blob/47f5b2cfe2a2738fd54eae9f8439817f6a22034e/B_yacc/1/y1.tab.h#L2
[5]: https://github.com/VirtualMonitor/VirtualMonitor/blob/71d1bf9b1e7b392a7bd0c73dc217138dc5865651/src/VBox/Additions/x11/x11include/xorg-server-1.8.0/parser.h#L2
[6]: https://github.com/bspaulding/DrawTest/blob/3f773ceb13de14275429036b9cbc5aa19e29bab9/Framework/OpenEars.framework/Versions/A/Headers/jsgf_parser.h#L2

Reviewed By: xazax.hun

Differential Revision: https://reviews.llvm.org/D114510

[mlir][linalg][bufferize][NFC] Utilize isWritable for FuncOps

This is a cleanup of ModuleBufferization. Instead of storing information about writable function arguments in BufferizationAliasInfo, we can use isWritable and make the decision there, based on dialect-specifc bufferization state.

Differential Revision: https://reviews.llvm.org/D114930