[Codegen_LLVM] Directly load scalar that we'd load as vector and rein… #6809
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| bool test_all(Target t) { | ||
| bool success = true; | ||
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| success &= test_with_chunk_type<uint8_t>(t); |
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There is some kind of failure to simplify for the i8 chunk type somewhere in halide:
let t5 = b0[(store.min.0 + store.s0.x.rebased)*2]
store[store.s0.x.rebased] = uint64((uint16)reinterpret(ramp(t5, b0[((store.min.0 + store.s0.x.rebased)*2) + 1] - t5, 2)))
but suddenly it's fine for larger types:
store$1[store$1.s0.x.rebased] = uint64((uint32)reinterpret(b3[ramp((store$1.min.0 + store$1.s0.x.rebased)*4, 1, 4) aligned(4, 0)]))
…terpret Second (of three) pieces of the load widening puzzle. Here, the codegen is taught to directly emit scalar loads, instead of doing vector load and `bitcast`ing it. Refs. halide#6801 Refs. halide#6756 Refs. halide#6775
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| LoadInst *load = builder->CreateAlignedLoad( | ||
| llvm_dst, ptr, llvm::Align(l->type.bytes())); | ||
| // FIXME: can we emit better TBAA for constant indexes here? | ||
| add_tbaa_metadata(load, l->name, /*index=*/Expr()); |
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I think it's correct to use the original load index here, because the tbaa metadata is all in terms of the allocated type before the reinterpret.
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Ah no, wait, of course it is, because we really don't change which bytes we load.
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The implementation makes sense, aside from my concerns about using the reinterpret intrinsic to change vector lanes, but the test is not great - We don't use vector types in front-end code, and I have no idea what might break if we did. I guess it's OK as a temporary measure, though the weird failure with uint8s is alarming and might indicate that some assumption is being violated somewhere. |
Right. Well, i'm not sure how else to write that test given what's currently available :)
It's some missed simplification. In good case, it is simplified during |
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Where does this PR stand? |
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I guess, |
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Is this PR still active? |
Yes, it's all connected (©)!
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…terpret
Second (of three) pieces of the load widening puzzle.
Here, the codegen is taught to directly emit scalar loads,
instead of doing vector load and
bitcasting it.Refs. #6801
Refs. #6756
Refs. #6775