Lower OpFNegate directly to fneg #2739
Merged
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
Update SPIRVReader to lower OpFNegate directly to fneg. By doing this the code in SpirvLowerMath can be updated to remove the change to add a canonicalize for any fneg. The motivation for this is that InstCombine can introduce fneg instructions (after some recent upstream llvm changes) and in this case we don't want to blindly add a canonicalize as this invalidates e.g. xor 0x8000000 val -> fneg val. It makes more sense to handle the requirement to treat OpFNegate as a floating point instruction at the point it is lowered (llvm fneg is not, hence the reason we may need the canonicalize intrinsic).
Test summary for commit 8aaf5a4CTS tests (Failed: 0/139021)
Ubuntu 22.04, Navi3xUbuntu 20.04, Navi2x |
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Outdated suggestions cannot be applied.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.
Update SPIRVReader to lower OpFNegate directly to fneg. By doing this the code in SpirvLowerMath can be updated to remove the change to add a canonicalize for any fneg.
The motivation for this is that InstCombine can introduce fneg instructions (after some recent upstream llvm changes) and in this case we don't want to blindly add a canonicalize as this invalidates e.g. xor 0x8000000 val -> fneg val.
It makes more sense to handle the requirement to treat OpFNegate as a floating point instruction at the point it is lowered (llvm fneg is not, hence the reason we may need the canonicalize intrinsic).