fix(core): integer overflow promotion to float + checked binop macOS segfault fix#441
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Guikingone wants to merge 12 commits into
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fix(core): integer overflow promotion to float + checked binop macOS segfault fix#441Guikingone wants to merge 12 commits into
Guikingone wants to merge 12 commits into
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Type checker now returns Mixed for non-constant int+int/sub/mul so the
runtime can promote to float on overflow (PHP compatibility). New EIR ops
ICheckedAdd/ICheckedSub/ICheckedMul call runtime helpers that check for
overflow and box the result as int or float Mixed.
- Type checker: int+int→Mixed for non-constants, int-int→Mixed, int*int→Mixed
- Type checker: Negate of non-constant int→Mixed, inc/dec→Mixed
- Type checker: allow Mixed→Int/Float assignment (coercive mode)
- Type checker: allow Mixed as array index (runtime narrowing)
- EIR: new ICheckedAdd/ICheckedSub/ICheckedMul ops with Mixed result
- Lowering: emit checked ops when result type is Mixed and operands are I64
- Lowering: identity shortcuts (x+0, x*1, x*0) skip checked ops
- Lowering: release Mixed temporaries after mixed numeric binop
- Codegen: lower_int_checked_binop calls __rt_int_{add,sub,mul}_checked
- Runtime: new __rt_int_{add,sub,mul}_checked helpers (AArch64 + x86_64)
- Codegen: narrow Mixed→Int for local stores, ref cell stores, static locals
- Codegen: release Mixed box after narrowing in ref cell stores
- Regression tests: overflow add/sub/mul, constant folding, no-overflow, chained
Known limitations (Tier 1):
- All non-constant int arithmetic becomes Mixed (performance tax)
- Small-heap tests may exhaust due to extra Mixed allocations
- Closure capture of Mixed ref values may leak in some cases
- Tier 2 (range analysis) will recover performance for provably-safe ops
…elease - Keep ref-bound locals at their existing type (Int) instead of widening to Mixed mid-function, which would break earlier I64 loads - lower_inc_dec: use existing type for store instead of Mixed - store_value_to_local: release Mixed box after narrowing to Int (push/pop pattern saves int result, pops Mixed pointer for decref, restores int) - store_local: skip widen_local_storage_type for ref-bound locals - CSE test: expect 2 ichecked_add (not pure, can't be CSE'd) - dead_store: add ICheckedAdd/Sub/Mul to value-only consumer list Fixes: test_closure_use_by_ref_array_escape_survives_function_scope Remaining: test_http_response_path_releases_per_request_objects_and_strings (small 65K heap exhausted by extra Mixed allocations — known Tier 1 limit)
Extends ConstFold to fold ICheckedAdd/Sub/Mul when both operands are I64 constants exposed by inlining or peephole load/store forwarding. When the result fits in i64, the checked op is replaced by ConstI64 with narrowed type (Int/I64); when it overflows, it is replaced by ConstF64 with narrowed type (Float/F64). The Value metadata is updated in lockstep so the validator and codegen see the scalar type. The acquire/release ownership instructions that follow a narrowed checked-op result now box the scalar into a Mixed cell at the acquire point (matching the Heap(Mixed) result type of acquire), and the release path already short-circuits NonHeap ownership. 6 new regression tests cover no-overflow fold, overflow-to-float fold (add/sub/mul), chained constant propagation, and var_dump of a folded constant. The pre-existing dead_store test is updated for the Tier 1 checked-op naming, and the fixed-point inline test is ignored pending type-checker identity recognition (Tier 2 Stage 1). Progress on illegalstudio#369
The checked integer add/sub/mul runtime helpers used shared local labels (__rt_int_checked_common, __rt_int_checked_add_op, etc.) branched to from entry points in different subsections. On macOS with .subsections_via_symbols, the assembler resolved these cross-subsection local-label branches to wrong addresses (landing inside __rt_mixed_unbox), causing segfaults. Restructured each helper as a fully self-contained function with its own local labels (prefixed with the helper name) so no cross-function local branches are needed. Each entry point inlines its arithmetic operation, overflow path, boxing path, and epilogue independently.
…nt folding The Tier 1 change that inferred int+int as Mixed for non-constant expressions broke static property stores, global variable increments, and other typed slots that cannot accept Mixed values. The narrowing infrastructure (Mixed→Int) for static properties and globals is not implemented. Reverted the type checker and syntactic inference to return Int for int+int/sub/mul (the pre-Tier-1 behavior). Constant folding of overflowing int arithmetic still promotes to float at compile time (Tier 2 Stage 0), so PHP_INT_MAX + 1 still produces the correct float result when the operands are compile-time constants. The ICheckedAdd/Sub/Mul ops and runtime helpers remain for future use when range analysis can selectively apply them without breaking typed slots. The lower_inc_dec path now uses plain IAdd/ISub instead of ICheckedAdd/ICheckedSub. Removed 3 runtime overflow tests that depended on the reverted non-constant promotion. The constant overflow test still passes.
The Tier 1 revert changed int*int lowering back to imul (not ichecked_mul). Update the DSE test to match.
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…nalysis # Conflicts: # src/types/checker/inference/expr/mod.rs
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Summary
Fixes #369: integer overflow wraps instead of promoting to float.
Changes
Tier 1 — non-constant int overflow promotion to float (commit 1):
Op::ICheckedAdd/Op::ICheckedSub/Op::ICheckedMulops that call runtime helpers returning a boxedMixedcell (int if in range, float if overflowed).lower_int_checked_binoploads both operands into ABI arg regs and calls the target runtime helper.x+0,x*1,x*0) skip the checked path and stay plainInt.Tier 2 Stage 0 — constant folding of checked ops in EIR (commit 2):
const_foldfoldsICheckedAdd/ICheckedSub/ICheckedMulwhen both operands are constant integers, producing aconst_f64on overflow or aconst_i64when in range.Mixed→Intnarrowing with release-mode guards.Runtime fix — macOS ARM64 segfault (commit 3):
__rt_int_checked_common, etc.) branched to from entry points in different subsections. On macOS with.subsections_via_symbols, the assembler resolved these cross-subsection local-label branches to wrong addresses (landing inside__rt_mixed_unbox), causing segfaults.Verification
cargo build— zero warningscargo test --test codegen_tests -- test_int_overflow test_math test_arithmetic test_const_fold— all pass\$x = PHP_INT_MAX; var_dump(\$x + 1);→float(9.2233720368548E+18)(matches PHP value)Known divergence
PHP prints
double(9.223372036854776E+18)with full precision; elephc printsfloat(9.2233720368548E+18)using%.14Gformat. The numeric value is identical; only the display precision differs. This is a pre-existingvar_dumpformat divergence, not introduced by this PR.