repro large variant timeout #8042
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cristianoc
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Dec 9, 2025
…mplification This PR fixes two sources of exponential compilation time: 1. **Boolean expression simplification** (`js_exp_make.ml`): The `simplify_and_` function had O(3^n) recursive behavior when simplifying nested AND expressions. Added a depth limit (10) to prevent exponential blowup while preserving optimizations for normal cases. Fixes the issue reported in #8039 and #8042 (large unboxed variants). Note: PR #8039's diagnosis of "infinite recursion" was incorrect - the actual issue was exponential blowup, not infinite loops. 2. **Exhaustiveness checking** (`parmatch.ml`): The `exhaust_gadt` function had exponential complexity (~4^n) when checking exhaustiveness for dict pattern matching. Added a call count limit (1000) that conservatively reports non-exhaustive when exceeded, preventing hangs while maintaining correctness. Performance improvements: - Large unboxed variants (28 cases): 3.79s -> 0.03s (126x faster) - Dict pattern matching (6 cases): 0.94s -> 0.04s (24x faster) Added test cases for both scenarios. Closes #8074 Closes #8039 Closes #8042
cristianoc
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Dec 9, 2025
…mplification This PR fixes two sources of exponential compilation time: 1. **Boolean expression simplification** (`js_exp_make.ml`): The `simplify_and_` function had O(3^n) recursive behavior when simplifying nested AND expressions. Added a depth limit (10) to prevent exponential blowup while preserving optimizations for normal cases. Fixes the issue reported in #8039 and #8042 (large unboxed variants). Note: PR #8039's diagnosis of "infinite recursion" was incorrect - the actual issue was exponential blowup, not infinite loops. 2. **Exhaustiveness checking** (`parmatch.ml`): The `exhaust_gadt` function had exponential complexity (~4^n) when checking exhaustiveness for dict pattern matching. Added a call count limit (1000) that conservatively reports non-exhaustive when exceeded, preventing hangs while maintaining correctness. Performance improvements: - Large unboxed variants (28 cases): 3.79s -> 0.03s (126x faster) - Dict pattern matching (6 cases): 0.94s -> 0.04s (24x faster) Added test cases for both scenarios. Closes #8074 Closes #8039 Closes #8042
cknitt
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Dec 9, 2025
…mplification This PR fixes two sources of exponential compilation time: 1. **Boolean expression simplification** (`js_exp_make.ml`): The `simplify_and_` function had O(3^n) recursive behavior when simplifying nested AND expressions. Added a depth limit (10) to prevent exponential blowup while preserving optimizations for normal cases. Fixes the issue reported in rescript-lang#8039 and rescript-lang#8042 (large unboxed variants). Note: PR rescript-lang#8039's diagnosis of "infinite recursion" was incorrect - the actual issue was exponential blowup, not infinite loops. 2. **Exhaustiveness checking** (`parmatch.ml`): The `exhaust_gadt` function had exponential complexity (~4^n) when checking exhaustiveness for dict pattern matching. Added a call count limit (1000) that conservatively reports non-exhaustive when exceeded, preventing hangs while maintaining correctness. Performance improvements: - Large unboxed variants (28 cases): 3.79s -> 0.03s (126x faster) - Dict pattern matching (6 cases): 0.94s -> 0.04s (24x faster) Added test cases for both scenarios. Closes rescript-lang#8074 Closes rescript-lang#8039 Closes rescript-lang#8042
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for #8039