[RISCV] Match constant indices of non-index type when forming strided ops #65777
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Does this allow a vector of i8 indices like <0, 128, 0, 128, 0, 128, 0, 128> to be considered a stride of 128? I'm traveling today so cant easily check. |
Yep, it gets this wrong. I'm going to add the reduced test case, and then rework the patch. Good catch. |
When checking to see if our index expressions can be converted into strided operations, we previously gave up if the index type wasn't an exact match for the intptrty for the address. Instead, we can ask known bits how many bits are needed, and proceed as long as the number of required bits fits in intptrty. Note that the motivation of this is mostly test cleanup. We canonicalize at IR such that the gep index will match the intptrty. This is mostly useful so that we can write both RV32 and RV64 tests from the same source. Its also helpful in preventing confusion - I've stumbled across this at least four times now and wasted time each one. Interestingly, this does appear to catch some loop cases that O3 does not canonicalize. I don't think the vectorizer is likely to emit indices narrower that intptr, but if another frontend did, this might pick them up. This may also pick up some pass ordering problems, but that's a happy accident at best.
preames
force-pushed
the
riscv-gather-scatter-index-active-bits
branch
from
1b7ac58
to
c03ef26
Compare
preames
changed the title
|
Pushed a much more restricted version which still covers my practical interest. Hopefully, this one is actually correct. |
topperc
approved these changes
Sep 16, 2023
| // than the pointer type. Adding the stride later may not wrap correctly. | ||
| // Technically we could handle wider indices, but I don't expect that in | ||
| // practice. | ||
| // We need the number of significant bits to match the index type. IF it |
preames
added a commit
that referenced
this pull request
Sep 18, 2023
… ops (#65777) When checking to see if our index expressions can be converted into strided operations, we previously gave up if the index type wasn't an exact match for the intptrty for the address. Per gep semantics, this mismatch implies a sext or trunc cast to the respective index type. For constants, go ahead and evaluate that cast instead of giving up. Note that the motivation of this is mostly test cleanup. We canonicalize at IR such that the gep index will match the intptrty. This is mostly useful so that we can write both RV32 and RV64 tests from the same source. Its also helpful in preventing confusion - I've stumbled across this at least four times now and wasted time each one. Note: The test change for scatters unit stride cases contains a minor regression for rv32 and 64 bit indices. This is an artifact of order in which changes are landing. This will be addressed in a near future change for all configurations.
|
Landed as 0722800 |
ZijunZhaoCCK
pushed a commit
to ZijunZhaoCCK/llvm-project
that referenced
this pull request
Sep 19, 2023
… ops (llvm#65777) When checking to see if our index expressions can be converted into strided operations, we previously gave up if the index type wasn't an exact match for the intptrty for the address. Per gep semantics, this mismatch implies a sext or trunc cast to the respective index type. For constants, go ahead and evaluate that cast instead of giving up. Note that the motivation of this is mostly test cleanup. We canonicalize at IR such that the gep index will match the intptrty. This is mostly useful so that we can write both RV32 and RV64 tests from the same source. Its also helpful in preventing confusion - I've stumbled across this at least four times now and wasted time each one. Note: The test change for scatters unit stride cases contains a minor regression for rv32 and 64 bit indices. This is an artifact of order in which changes are landing. This will be addressed in a near future change for all configurations.
zahiraam
pushed a commit
to tahonermann/llvm-project
that referenced
this pull request
Oct 24, 2023
… ops (llvm#65777) When checking to see if our index expressions can be converted into strided operations, we previously gave up if the index type wasn't an exact match for the intptrty for the address. Per gep semantics, this mismatch implies a sext or trunc cast to the respective index type. For constants, go ahead and evaluate that cast instead of giving up. Note that the motivation of this is mostly test cleanup. We canonicalize at IR such that the gep index will match the intptrty. This is mostly useful so that we can write both RV32 and RV64 tests from the same source. Its also helpful in preventing confusion - I've stumbled across this at least four times now and wasted time each one. Note: The test change for scatters unit stride cases contains a minor regression for rv32 and 64 bit indices. This is an artifact of order in which changes are landing. This will be addressed in a near future change for all configurations.
zahiraam
pushed a commit
to tahonermann/llvm-project
that referenced
this pull request
Oct 24, 2023
… ops (llvm#65777) When checking to see if our index expressions can be converted into strided operations, we previously gave up if the index type wasn't an exact match for the intptrty for the address. Per gep semantics, this mismatch implies a sext or trunc cast to the respective index type. For constants, go ahead and evaluate that cast instead of giving up. Note that the motivation of this is mostly test cleanup. We canonicalize at IR such that the gep index will match the intptrty. This is mostly useful so that we can write both RV32 and RV64 tests from the same source. Its also helpful in preventing confusion - I've stumbled across this at least four times now and wasted time each one. Note: The test change for scatters unit stride cases contains a minor regression for rv32 and 64 bit indices. This is an artifact of order in which changes are landing. This will be addressed in a near future change for all configurations.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
When checking to see if our index expressions can be converted into strided operations, we previously gave up if the index type wasn't an exact match for the intptrty for the address. Per gep semantics, this mismatch implies a sext or trunc cast to the respective index type. For constants, go ahead and evaluate that cast instead of giving up.
Note that the motivation of this is mostly test cleanup. We canonicalize at IR such that the gep index will match the intptrty. This is mostly useful so that we can write both RV32 and RV64 tests from the same source. Its also helpful in preventing confusion - I've stumbled across this at least four times now and wasted time each one.