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[mono] Workaround MSVC miscompiling sgen_clz #114786

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Merged
merged 1 commit into from
Apr 17, 2025
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[mono] Workaround MSVC miscompiling sgen_clz #114786

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5 changes: 4 additions & 1 deletion src/mono/mono/sgen/sgen-array-list.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,10 @@ static inline guint32
sgen_clz (guint32 x)
{
gulong leading_zero_bits;
return _BitScanReverse (&leading_zero_bits, (gulong)x) ? 31 - leading_zero_bits : 32;
if (_BitScanReverse (&leading_zero_bits, (gulong)x))
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Copilot AI Apr 17, 2025

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Consider adding an inline comment above this if/else block to explain that the change is a workaround for the MSVC miscompilation issue encountered in VS 17.13.2.

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return 31 - leading_zero_bits;
else
return 32;
}
#elif defined(ENABLE_MSVC_LZCNT) && defined(_MSC_VER)
static inline guint32
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