[LangRef] Correct documentation for roundeven

[tgross35]

Langref for roundeven implies that the C standard function roundeven may raise floating point exceptions. However, this is not correct; C23 does not mention exceptions for roundeven, and per 1 FE_INEXACT is never raised.

Clarify that LLVM's roundeven behaves the same.

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[llvmbot]

@llvm/pr-subscribers-llvm-ir

Author: Trevor Gross (tgross35)

Changes

Langref for roundeven implies that the C standard function roundeven may raise floating point exceptions. However, this is not correct; C23 does not mention exceptions for roundeven, and per 1 FE_INEXACT is never raised.

Clarify that LLVM's roundeven behaves the same.

---

Full diff: https://github.com/llvm/llvm-project/pull/125452.diff

1 Files Affected:

• (modified) llvm/docs/LangRef.rst (+2-2)

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 8891aedcb58e55..bd9c522987834f 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -17255,8 +17255,8 @@ Semantics:
 """"""""""
 
 This function implements IEEE-754 operation ``roundToIntegralTiesToEven``. It
-also behaves in the same way as C standard function ``roundeven``, except that
-it does not raise floating point exceptions.
+also behaves in the same way as C standard function ``roundeven``, including
+that it disregards rounding mode and does not raise floating point exceptions.
 
 
 '``llvm.lround.*``' Intrinsic

[tgross35]

@arsenm it looks like you have reviewed some of the sections around here, would you mind taking a look at this?

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[tgross35]

Thanks!