commit 0961b158576d90b5ac5d3b2bb2aaee1c55624ec0
author Giuseppe Rossini <giuseppe.rossini@amd.com> Wed Jul 17 17:05:40 2024 +0100
committer Copybara-Service <copybara-worker@google.com> Wed Jul 17 09:11:15 2024 -0700
tree b496f49a0251bcd48574e95ee382cb82f0c35f97
parent 7cb6b2e16ab6df8a20086aae4e43e74791e37087

[mlir] Fix block merging (#97697)

With this PR I am trying to address:
https://github.com/llvm/llvm-project/issues/63230.

What changed:
- While merging identical blocks, don't add a block argument if it is
"identical" to another block argument. I.e., if the two block arguments
refer to the same `Value`. The operations operands in the block will
point to the argument we already inserted. This needs to happen to all
the arguments we pass to the different successors of the parent block
- After merged the blocks, get rid of "unnecessary" arguments. I.e., if
all the predecessors pass the same block argument, there is no need to
pass it as an argument.
- This last simplification clashed with
`BufferDeallocationSimplification`. The reason, I think, is that the two
simplifications are clashing. I.e., `BufferDeallocationSimplification`
contains an analysis based on the block structure. If we simplify the
block structure (by merging and/or dropping block arguments) the
analysis is invalid . The solution I found is to do a more prudent
simplification when running that pass.

**Note**: this a rework of #96871 . I ran all the integration tests
(`-DMLIR_INCLUDE_INTEGRATION_TESTS=ON`) and they passed.

GitOrigin-RevId: c63125d4533a22a200c3b5b1efb8ac3ce4b1cb69