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aykevl
dylanmckay
jacquesguan

Commits

rG2a6e39dbf84a: [AVR] Do not emit 'LPM Rd, Z' on devices without FeatureLPMX

Summary

The LPM instruction has three forms:

form	feature
LPM	hasLPM
LPM Rd, Z	hasLPMX
LPM Rd, Z+	hasLPMX

The second form is always selected in ISelDAGToDAG, even on devices
without FeatureLPMX. This patch emits "LPM + MOV" on devices with
only FeatureLPM.

Diff Detail

Repository: rG LLVM Github Monorepo

Event Timeline

benshi001 created this revision.Jan 8 2023, 8:13 PM

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benshi001 requested review of this revision.Jan 8 2023, 8:13 PM

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benshi001 updated this revision to Diff 487270.Jan 8 2023, 8:13 PM

benshi001 added a parent revision: D141221: [AVR] Fix incorrect expansion of the pseudo 'ELPMBRdZ' instruction.

benshi001 edited the summary of this revision. (Show Details)

benshi001 retitled this revision from [AVR] Do not emit 'LPM Rd, Z' on devices without FeatureLPMX to [AVR] Do not emit `LPM Rd, Z` on devices without FeatureLPMX.

benshi001 retitled this revision from [AVR] Do not emit `LPM Rd, Z` on devices without FeatureLPMX to [AVR] Do not emit 'LPM Rd, Z' on devices without 'FeatureLPMX'.Jan 8 2023, 8:19 PM

benshi001 edited the summary of this revision. (Show Details)

benshi001 set the repository for this revision to rG LLVM Github Monorepo.

benshi001 added inline comments.Jan 8 2023, 8:26 PM

llvm/lib/Target/AVR/AVRExpandPseudoInsts.cpp
869	`HasX` means if there is extended form of LPM/ELPM. `IsExt` means it is E(xtended)LPM, not (ordinray) LPM.
llvm/test/CodeGen/AVR/elpm.ll
161	The only difference between `CHECK` and `NOX` is that `lpm Rd, Z` is replaced by `lpm` + `mov Rd, R0`.