forked from OSchip/llvm-project
f84bc3793e
Summary: Previously, a extending load was represented at (G_*EXT (G_LOAD x)). This had a few drawbacks: * G_LOAD had to be legal for all sizes you could extend from, even if registers didn't naturally hold those sizes. * All sizes you could extend from had to be allocatable just in case the extend went missing (e.g. by optimization). * At minimum, G_*EXT and G_TRUNC had to be legal for these sizes. As we improve optimization of extends and truncates, this legality requirement would spread without considerable care w.r.t when certain combines were permitted. * The SelectionDAG importer required some ugly and fragile pattern rewriting to translate patterns into this style. This patch changes the representation to: * (G_[SZ]EXTLOAD x) * (G_LOAD x) any-extends when MMO.getSize() * 8 < ResultTy.getSizeInBits() which resolves these issues by allowing targets to work entirely in their native register sizes, and by having a more direct translation from SelectionDAG patterns. Each extending load can be lowered by the legalizer into separate extends and loads, however a target that supports s1 will need the any-extending load to extend to at least s8 since LLVM does not represent memory accesses smaller than 8 bit. The legalizer can widenScalar G_LOAD into an any-extending load but sign/zero-extending loads need help from something else like a combiner pass. A follow-up patch that adds combiner helpers for for this will follow. The new representation requires that the MMO correctly reflect the memory access so this has been corrected in a couple tests. I've also moved the extending loads to their own tests since they are (mostly) separate opcodes now. Additionally, the re-write appears to have invalidated two tests from select-with-no-legality-check.mir since the matcher table no longer contains loads that result in s1's and they aren't legal in AArch64 anymore. Depends on D45540 Reviewers: ab, aditya_nandakumar, bogner, rtereshin, volkan, rovka, javed.absar Reviewed By: rtereshin Subscribers: javed.absar, llvm-commits, kristof.beyls Differential Revision: https://reviews.llvm.org/D45541 llvm-svn: 331601 |
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| ARC | ||
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| BPF | ||
| Generic | ||
| Hexagon | ||
| Inputs | ||
| Lanai | ||
| MIR | ||
| MSP430 | ||
| Mips | ||
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| Nios2 | ||
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| Thumb | ||
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| WebAssembly | ||
| WinCFGuard | ||
| WinEH | ||
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