<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJylU0uPmzAQ_jXmMlpETEjIgUNeq0ZNq6pNH7fIgAmujI1ss7v8-44dsq8eeiiywGMz33wz802p67E4ceuALBIpHzpC7x2a-DkZpmyjTWfROCjrvomul6IZ0dxqtL8Y3ePeCOViKdEfhIUHbkZ4NFpdAH3hsWUODlAxBY5LGZNkR5L1qeXQ4VHPLhx0A4ozU46IM8GBZaMF531dyy2HZlCVExgUBrTwDIweVC0wSqdrDsyC5Q7K0afRoIcL92gQuoVyQA6vEsDf7dBxG4COxx-foOYNG6R7izqRvb73TwydOUkn20OHFYoWjhBEKOQqNfIm86TyRWLKnRst67PP69yk9JzMCM0JXQGhaQJkuZkA0w1sP-y3H--O683-iIH-ifHO7_P-18m74WOwGFceszgJDyd0kyTPLtcNIIfsCUi6ww5J-UL9uSENxrkB0ezG-ub9EsbjTODL3bsKvS7jjvf8WmGt_u6jb5ZrUUW3fvsIg8G2YxqAcqJxEsNP7vVE6BIbLoWq5Qi-OpNU1vfrw_c3rasqn9KRl7zmD18P3jDaMceNuLQh3aZlrYrqIq1X6YpFbHCtNoUalO6l7rmNBiOL1rne-v7Te1wX4dqhjCvtJ2YaHP-5643-zSuvZIEq4354sjRPVlFbJMmszrN0RhdpnafpbN4sVnSeV1mTl808TyPJSi5tQbINoVTxRwgQuCfZLvp_BqKgCcU1S_3K5nGZz2i2RHFk2aKqVgmWgndMyNjjxNpcIlMEyHK4WLyUwjr7coljJC6K80AYGTrhJC_eTJpvjAUTRjuInql6GvfpABG08QIIahjUnRPdO1lEIY8iJPEHU_N5eA>53809</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            InstSimplify folds rint() and nearby() ignoring the run-time rounding mode
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          nunoplopes
      </td>
    </tr>
</table>

<pre>
    Test `llvm/test/Transforms/InstSimplify/ConstProp/rint.ll` is very wrong for what I can tell.
The man page of nearbyint/rint says that these functions use the rounding mode as set by `fesetround`, but InstSimplify assumes the LLVM default rounding mode.

Example:
```llvm
define float @constant_fold_rint_f32_01() #0 {
; CHECK-LABEL: @constant_fold_rint_f32_01(
; CHECK-NEXT:    ret float 1.000000e+00
;
  %x = call float @nearbyintf(float 1.25) #0
  ret float %x
}
```

Depending on the rounding mode, this function returns 1.0 or 2.0. We can't blindly fold these AFAIU.

cc @LebedevRI @rotateright @fhahn
</pre>
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