[AArch64] Clarify that Anyext is OK for MOPS instructions. NFC #70298
Conversation
This file contains hidden or 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
The instruction should only read the bottom 8 bits of the register, so an anyext is OK here. Update the comment from zext->anyext to clarify. Closes llvm#70270
|
@llvm/pr-subscribers-backend-aarch64 Author: David Green (davemgreen) ChangesThe instruction should only read the bottom 8 bits of the register, so an anyext is OK here. Update the comment from zext->anyext to clarify. Closes #70270 Full diff: https://github.com/llvm/llvm-project/pull/70298.diff 1 Files Affected:
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
index 9fadc008de20628..6c1d25f62c21e76 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -1253,7 +1253,8 @@ bool AArch64LegalizerInfo::legalizeIntrinsic(LegalizerHelper &Helper,
}
case Intrinsic::aarch64_mops_memset_tag: {
assert(MI.getOpcode() == TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS);
- // Zext the value to 64 bit
+ // Anyext the value being set to 64 bit (only the bottom 8 bits are read by
+ // the instruction).
MachineIRBuilder MIB(MI);
auto &Value = MI.getOperand(3);
Register ZExtValueReg = MIB.buildAnyExt(LLT::scalar(64), Value).getReg(0);
@@ -1776,7 +1777,8 @@ bool AArch64LegalizerInfo::legalizeMemOps(MachineInstr &MI,
// Tagged version MOPSMemorySetTagged is legalised in legalizeIntrinsic
if (MI.getOpcode() == TargetOpcode::G_MEMSET) {
- // Zext the value operand to 64 bit
+ // Anyext the value being set to 64 bit (only the bottom 8 bits are read by
+ // the instruction).
auto &Value = MI.getOperand(1);
Register ZExtValueReg =
MIRBuilder.buildAnyExt(LLT::scalar(64), Value).getReg(0);
|
aemerson
approved these changes
Oct 26, 2023
|
The variable names still contain |
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.
The instruction should only read the bottom 8 bits of the register, so an anyext is OK here. Update the comment from zext->anyext to clarify.
Closes #70270