bf47146085
lowerFor's by-value element fetch emitted index_get on the array VALUE; the emitter realizes that as a whole-array spill to a stack temp + GEP, per iteration — O(N^2) bytes copied per loop (and pre-0109 it also grew the stack per iteration, segfaulting a [4096]s64 loop). When the iterable is an array with addressable storage (and not deref'd from a pointer, whose identifier alloca holds the pointer rather than the array), the fetch is now index_gep on the storage + one element load. Storage-less arrays keep the index_get fallback. The loaded element remains a copy — mutating the capture does not write back. Regression: examples/0048-basic-for-array-large.sx (sum over 4096 elements + by-value copy-guard).
25 lines
901 B
Plaintext
25 lines
901 B
Plaintext
// Collection-form `for` over an array, by-value capture: each iteration
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// reads ONE element from the array's storage (GEP + load), and the capture
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// stays a copy — mutating it never writes back to the array.
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// Regression (issue 0110): the element fetch was `index_get` on the array
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// VALUE, spilling a full copy of the array to a stack temp per iteration —
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// O(N²) bytes copied, and (pre-0109) per-iteration stack growth that made
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// this 4096-element loop segfault.
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#import "modules/std.sx";
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main :: () -> s32 {
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arr : [4096]s64 = ---;
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i := 0;
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while i < 4096 { arr[i] = i; i += 1; }
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sum := 0;
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for arr: (x) { sum += x; }
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print("sum={}\n", sum);
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// By-value capture is a copy: mutating it leaves the array untouched.
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small : [3]s64 = .[10, 20, 30];
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for small: (x) { x += 100; }
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print("copy-guard: {} {} {}\n", small[0], small[1], small[2]);
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0
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}
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