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some small gc optimizations #33828

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Merged
JeffBezanson merged 2 commits into from
Nov 13, 2019
Merged

some small gc optimizations #33828

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a77b2c1
codegen: remove some unnecessary write-barriers
vtjnash Nov 12, 2019
629d1a6
gc: add early-out for empty arrays
vtjnash Nov 12, 2019
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8 changes: 5 additions & 3 deletions src/cgutils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2722,12 +2722,14 @@ static jl_cgval_t emit_new_struct(jl_codectx_t &ctx, jl_value_t *ty, size_t narg
ConstantInt::get(T_size, jl_field_offset(sty, i) + jl_field_size(sty, i) - 1))));
}
}
bool need_wb = false;
// TODO: verify that nargs <= nf (currently handled by front-end)
for (size_t i = 0; i < nargs; i++) {
const jl_cgval_t &rhs = argv[i];
if (jl_field_isptr(sty, i) && !rhs.isboxed)
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@yuyichao yuyichao Nov 12, 2019

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What was the condition that required this previously? It was pre linear IR so I won't be surprised if it isn't needed anymore but I do remember it was quite non-obvious so I want to make sure it's not needed anymore...

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@vtjnash vtjnash Nov 12, 2019

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I thought it should be OK now because of linear IR, but I could be wrong. CI seems OK with it.

need_wb = true;
bool need_wb; // set to true if the store might cause the allocation of a box newer than the struct
if (jl_field_isptr(sty, i))
need_wb = !rhs.isboxed;
else
need_wb = false;
emit_typecheck(ctx, rhs, jl_svecref(sty->types, i), "new");
emit_setfield(ctx, sty, strctinfo, i, rhs, false, need_wb);
}
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2 changes: 1 addition & 1 deletion src/gc.c
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Expand Up @@ -2334,7 +2334,7 @@ mark: {
}
goto pop;
}
if (!flags.ptrarray || a->data == NULL)
if (!flags.ptrarray || a->data == NULL || jl_array_len(a) == 0)
goto pop;
size_t l = jl_array_len(a);
uintptr_t nptr = (l << 2) | (bits & GC_OLD);
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