[LangRef] Clarify absence of rounding guarantees for fmuladd.

During the review of D67434, it was recommended to make fmuladd's
behavior more explicit. D67434 depends on this interpretation.

Reviewers: efriedma, jfb, reames, scanon, lebedev.ri, spatel

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D67552

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372892 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/LangRef.rst b/docs/LangRef.rst
index a38356aa27eb7a1ecf7058e1d4c136402f601ea0..ac1db593ac8ffb1680fdb37c6c49a4abeb509b6f 100644 (file)
--- a/docs/LangRef.rst
+++ b/docs/LangRef.rst
@@ -13959,12 +13959,12 @@ The expression:
 
       %0 = call float @llvm.fmuladd.f32(%a, %b, %c)
 
-is equivalent to the expression a \* b + c, except that rounding will
-not be performed between the multiplication and addition steps if the
-code generator fuses the operations. Fusion is not guaranteed, even if
-the target platform supports it. If a fused multiply-add is required, the
-corresponding :ref:`llvm.fma <int_fma>` intrinsic function should be used
-instead. This never sets errno, just as '``llvm.fma.*``'.
+is equivalent to the expression a \* b + c, except that it is unspecified
+whether rounding will be performed between the multiplication and addition
+steps. Fusion is not guaranteed, even if the target platform supports it.
+If a fused multiply-add is required, the corresponding
+:ref:`llvm.fma <int_fma>` intrinsic function should be used instead.
+This never sets errno, just as '``llvm.fma.*``'.
 
 Examples:
 """""""""