PIPE-10437 LegalizeIntegerTypes#9
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What
Fixes a HIGH severity SAST finding (PIPE-10437) in lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp at line 830, reported by Wiz.
Problem
In the PromoteIntRes_VAARG function, the expression i * RegVT.getSizeInBits() performs a unsigned × unsigned multiplication in 32-bit space. The result is then implicitly widened to int64_t when passed to DAG.getConstant(). Since the widening happens after the multiplication, the multiply can theoretically overflow before the conversion takes place.
This is flagged as CWE-190: Integer Overflow or Wraparound.
Fix
Cast i to uint64_t before the multiplication so the entire operation is performed in 64-bit space, eliminating any overflow window.
Why this is safe
getConstant() already accepts int64_t — no signature change needed
The cast is a widening conversion (uint32_t → uint64_t) — zero data loss risk
Produces identical machine code for all realistic input values
No functional behavior change — only eliminates the theoretical overflow path
No other files, headers, or dependencies are affected
Risk assessment
Functional behavior - None
Other files / dependencies - None
Build / compilation - None
Existing tests - All pass — no behavioral change