Fix BigInteger to double conversion rounding on s390x - #131491
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abhishekabhi73cc-design wants to merge 3 commits into
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Fix BigInteger to double conversion rounding on s390x#131491abhishekabhi73cc-design wants to merge 3 commits into
abhishekabhi73cc-design wants to merge 3 commits into
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Summary
Fix the rounding mode used by the s390x
CDLGBRinstruction during BigInteger to double conversion in the Mono JIT.The CDLGBR instruction encodes the IEEE-754 rounding mode in its M3 field. The implementation was using M3 = 6 (round toward +infinity), which produced incorrect results for values that require round-to-nearest-even behavior.
This change updates the M3 field to 4, which corresponds to round to nearest with ties to even, matching the expected .NET floating-point conversion semantics.