[PATCH] D128427: [LoongArch] Add codegen support for load/store operations

Sat Jul 2 00:58:05 PDT 2022

xen0n added inline comments.

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Comment at: llvm/test/CodeGen/LoongArch/ir-instruction/load-store.ll:329
+; LA64-NEXT:    lu12i.w $a1, -136485
+; LA64-NEXT:    ori $a1, $a1, 3823
+; LA64-NEXT:    lu32i.d $a1, -147729
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SixWeining wrote:
> xry111 wrote:
> > Based on the previous discussion, should we move "ori" to the last instruction in the long immediate load sequence and change it to "addi.d" if possible, so a peephole optimization would be able to combine "addi.d" and "ld" into one instruction?
> In terms of principle this can be implemented. But seems that this is only suitable for very few scenarios (maybe only when accessing a constant memory address). I'm not very sure.
I think this depends on the micro-architecture. If `lu12i.w; ori; lu32i.d; lu52i.d` sequences or variations of it are macro-op-fusioned, then breaking away from the current pattern could instead harm performance. OTOH it could be a net benefit but as @SixWeining pointed out this case of accessing absolute addresses is probably too rare to justify a special-case.

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  https://reviews.llvm.org/D128427/new/

https://reviews.llvm.org/D128427