[mypyc] Avoid boxing/unboxing when coercing between tuple types #14899
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Instead, coerce each tuple item individually. This makes some coercions between tuple types much faster, primarily because there is less (or no) allocation and deallocation going on. This speeds up the raytrace benchmark by about 7% (when using native floats). Related to mypyc/mypyc#99.
| @@ -666,13 +665,11 @@ L0: | |||
| return r0 | |||
| def g(): | |||
| r0 :: tuple[int, int] | |||
| r1 :: object | |||
| r2 :: tuple[int64, int64] | |||
| r1 :: tuple[int64, int64] | |||
| L0: | |||
| r0 = (2, 4) | |||
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It's a little unfortunate that this remains in the IR, but it's nothing DCE can't fix if we ever implement it.
tuple_T288 CPyDef_g(void) {
tuple_T2II cpy_r_r0;
tuple_T288 cpy_r_r1;
CPyL0: ;
cpy_r_r0.f0 = 2;
cpy_r_r0.f1 = 4;
CPyTagged_INCREF(cpy_r_r0.f0);
CPyTagged_INCREF(cpy_r_r0.f1);
CPyTagged_DECREF(cpy_r_r0.f0);
CPyTagged_DECREF(cpy_r_r0.f1);
cpy_r_r1.f0 = 1;
cpy_r_r1.f1 = 2;
return cpy_r_r1;
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The C compiler may optimize some of these away. Also, optimizing these shouldn't be too difficult in mypyc. Added mypyc/mypyc#983 to track this.
| # We can't reuse register values, since they can be modified. | ||
| if not isinstance(item, Register): |
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This is not a blocking comment, moreso for my own learning. What situations exist where a register is modified during the coerce operation?
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This is about code like this:
t = (n, 0)
n += 1
t2: tuple[float, float] = tWe can't use n to refer to the first item of t when constructing t2, since n was incremented on line 2.
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Ah right. I should've thought of that, painfully obvious now you show it. Thanks!
Instead, coerce each tuple item individually. This makes some coercions between tuple types much faster, primarily because there is less (or no) allocation and deallocation going on.
This speeds up the raytrace benchmark by about 7% (when using native floats).
Related to mypyc/mypyc#99.