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    <div class="moz-cite-prefix">On 08/31/2017 04:55 PM, Richard Smith
      via cfe-dev wrote:<br>
    </div>
    <blockquote
cite="mid:CAOfiQq=wWKhk9FazzsDuYACLJffOA8=0q8HEZaOgGct7iJ5gDw@mail.gmail.com"
      type="cite">
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        <div class="gmail_extra">
          <div class="gmail_quote">On 31 August 2017 at 14:48, Kaylor,
            Andrew via cfe-dev <span dir="ltr"><<a
                moz-do-not-send="true"
                href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>></span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin:0 0 0
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                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">I
                      had considered the inlining issue, and updating
                      the inliner to handle this was on my list of
                      things yet to be done.  I’m not sure I understand
                      what you’re saying about LTO. </span></p>
                </div>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div>The point about LTO was that you can't solve the
              inlining problem by using intrinsics throughout an entire
              module if FENV_ACCESS is used anywhere, because you might
              see code from outside the module.</div>
            <div><br>
            </div>
            <blockquote class="gmail_quote" style="margin:0 0 0
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                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">There
                      are some points about the standard specification
                      that seem a bit unclear to me, specifically with
                      regard to how things work if you call an
                      FENV_ACCESS-off function from within an
                      FENV_ACCESS-on scope.  I believe that when I
                      talked with our front end guys here about that our
                      conclusion was that doing that sort of thing is
                      undefined behavior.  I’m not sure if this is
                      related to your LTO concern or not.</span></p>
                </div>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div>I don't think that observation helps much, since you
              can call FENV_ACCESS-on code from FENV_ACCESS-off code,
              which is equally problematic. It's also not true that the
              above case results in UB: you only get UB if you're in a
              non-default FP mode when you enter the FENV_ACCESS-off
              code, or if that code attempts to inspect or alter the FP
              environment -- so the hoisting problem still seems to
              exist.</div>
            <div><br>
            </div>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
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                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">In
                      any event, you definitely raise some good
                      questions that I don’t have answers for.  I’ll
                      have to give this some more thought.</span></p>
                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">I
                      just want to add that one of the primary design
                      goals in what I’ve done so far was to not doing
                      anything that would inhibit optimizations or
                      require extra work on the part of the optimization
                      passes in the case where we don’t care about
                      FENV_ACCESS.  That requirement makes attaching
                      side-effects to the FP operations quite difficult.</span></p>
                </div>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div>Indeed; FWIW that approach seems like the right one to
              me. We need a very strong barrier between anything that
              might use feenableexcept and anything that might use
              LLVM's "pure" FP operations, and I don't believe we have
              such a thing in LLVM IR yet. So I don't think we're ready
              for frontend work on FENV_ACCESS, since we don't yet know
              how it will be represented in IR.</div>
          </div>
        </div>
      </div>
    </blockquote>
    <br>
    To be clear, we've had several extensive discussions about this, on
    and off list, and Andy has started adding the corresponding
    intrinsics into the IR. There was a presumption about a lack of
    mixing, however, and we do need to work out how to prevent mixing
    the native IR operations with the intrinsics (although, perhaps we
    just did that).<br>
    <br>
     -Hal<br>
    <br>
    <blockquote
cite="mid:CAOfiQq=wWKhk9FazzsDuYACLJffOA8=0q8HEZaOgGct7iJ5gDw@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div class="gmail_extra">
          <div class="gmail_quote">
            <div><span
style="color:rgb(31,73,125);font-family:Calibri,sans-serif;font-size:11pt"> </span></div>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
              <div link="blue" vlink="purple" lang="EN-US">
                <div class="m_1672052445564938120WordSection1">
                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">-Andy</span></p>
                  <p class="MsoNormal"><a moz-do-not-send="true"
                      name="m_1672052445564938120__MailEndCompose"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></a></p>
                  <p class="MsoNormal"><b><span
                        style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">
                      Richard Smith [mailto:<a moz-do-not-send="true"
                        href="mailto:richard@metafoo.co.uk"
                        target="_blank">richard@metafoo.co.uk</a>]
                      <br>
                      <b>Sent:</b> Thursday, August 31, 2017 2:32 PM</span></p>
                  <div>
                    <div class="h5"><br>
                      <b>To:</b> Kaylor, Andrew <<a
                        moz-do-not-send="true"
                        href="mailto:andrew.kaylor@intel.com"
                        target="_blank">andrew.kaylor@intel.com</a>><br>
                      <b>Cc:</b> Marcus Johnson <<a
                        moz-do-not-send="true"
                        href="mailto:bumblebritches57@gmail.com"
                        target="_blank">bumblebritches57@gmail.com</a>>;
                      Clang Dev <<a moz-do-not-send="true"
                        href="mailto:cfe-dev@lists.llvm.org"
                        target="_blank">cfe-dev@lists.llvm.org</a>>;
                      <a moz-do-not-send="true"
                        href="mailto:wei.ding2@amd.com" target="_blank">wei.ding2@amd.com</a><br>
                      <b>Subject:</b> Re: [cfe-dev] Why is #pragma STDC
                      FENV_ACCESS not supported?</div>
                  </div>
                  <div>
                    <div class="h5">
                      <p class="MsoNormal"> </p>
                      <div>
                        <p class="MsoNormal">I think that's also not
                          enough; you'd get the same problem after
                          inlining, and across modules with LTO. You
                          would need to also prevent any interprocedural
                          code motion across a FENV_ACCESS /
                          non-FENV_ACCESS boundary.</p>
                        <div>
                          <p class="MsoNormal"> </p>
                        </div>
                        <div>
                          <p class="MsoNormal">And even that doesn't
                            seem to be enough. Suppose that some scalar
                            optimization pass finds a clever way to
                            converts some integer operation into a
                            floating-point operation, such that it can
                            prove that the FP values never overflow (I
                            believe Chandler has an example of this that
                            comes up in some real crypto code). Now
                            suppose there's a case where the integer
                            operands are undef, but that the code in
                            question is bypassed in that case. If the FP
                            operations get hoisted, and you happen to
                            have FP exceptions enabled, you have a
                            potential miscompile.</p>
                        </div>
                        <div>
                          <div>
                            <p class="MsoNormal"> </p>
                          </div>
                          <div>
                            <p class="MsoNormal">Fundamentally, it seems
                              to me that feenableexcept is unsound in
                              the current LLVM IR model of floating
                              point, if we assume that fadd, fmul, fsub
                              etc do not have side-effects.</p>
                            <div>
                              <p class="MsoNormal"> </p>
                              <div>
                                <p class="MsoNormal">On 31 August 2017
                                  at 14:20, Kaylor, Andrew via cfe-dev
                                  <<a moz-do-not-send="true"
                                    href="mailto:cfe-dev@lists.llvm.org"
                                    target="_blank">cfe-dev@lists.llvm.org</a>>
                                  wrote:</p>
                                <blockquote
                                  style="border:none;border-left:solid
                                  #cccccc 1.0pt;padding:0in 0in 0in
                                  6.0pt;margin-left:4.8pt;margin-right:0in">
                                  <div>
                                    <div>
                                      <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">If
                                          that’s the case, we may need
                                          to use the constrained
                                          intrinsics for all FP
                                          operations when FENV_ACCESS is
                                          enabled anywhere in a
                                          function.</span></p>
                                      <p class="MsoNormal"><a
                                          moz-do-not-send="true"
                                          name="m_1672052445564938120_m_-2075974219545047674__MailEndCompose"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></a></p>
                                      <p class="MsoNormal"><b><span
                                            style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">
                                          Richard Smith [mailto:<a
                                            moz-do-not-send="true"
                                            href="mailto:richard@metafoo.co.uk"
                                            target="_blank">richard@metafoo.co.uk</a>]
                                          <br>
                                          <b>Sent:</b> Thursday, August
                                          31, 2017 2:18 PM<br>
                                          <b>To:</b> Kaylor, Andrew <<a
                                            moz-do-not-send="true"
                                            href="mailto:andrew.kaylor@intel.com"
                                            target="_blank">andrew.kaylor@intel.com</a>><br>
                                          <b>Cc:</b> Clang Dev <<a
                                            moz-do-not-send="true"
                                            href="mailto:cfe-dev@lists.llvm.org"
                                            target="_blank">cfe-dev@lists.llvm.org</a>>;
                                          Marcus Johnson <<a
                                            moz-do-not-send="true"
                                            href="mailto:bumblebritches57@gmail.com"
                                            target="_blank">bumblebritches57@gmail.com</a>>;
                                          <a moz-do-not-send="true"
                                            href="mailto:wei.ding2@amd.com"
                                            target="_blank">wei.ding2@amd.com</a></span></p>
                                      <div>
                                        <div>
                                          <p class="MsoNormal"><br>
                                            <b>Subject:</b> Re:
                                            [cfe-dev] Why is #pragma
                                            STDC FENV_ACCESS not
                                            supported?</p>
                                        </div>
                                      </div>
                                      <div>
                                        <div>
                                          <p class="MsoNormal"> </p>
                                          <div>
                                            <div>
                                              <div>
                                                <p class="MsoNormal">On
                                                  31 August 2017 at
                                                  14:14, Kaylor, Andrew
                                                  via cfe-dev <<a
                                                    moz-do-not-send="true"
href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>>
                                                  wrote:</p>
                                                <blockquote
                                                  style="border:none;border-left:solid
                                                  #cccccc
                                                  1.0pt;padding:0in 0in
                                                  0in
6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
                                                  <div>
                                                    <div>
                                                      <p
                                                        class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">I
                                                          believe that
                                                          we will rely
                                                          on
                                                          fedisableexcept()
                                                          being marked
                                                          as having
                                                          unmodeled
                                                          side-effects
                                                          to prevent a
                                                          hoist like
                                                          that.</span></p>
                                                    </div>
                                                  </div>
                                                </blockquote>
                                                <div>
                                                  <p class="MsoNormal"> </p>
                                                </div>
                                                <div>
                                                  <p class="MsoNormal">fadd
                                                    can be hoisted past
                                                    *anything*, can't
                                                    it?</p>
                                                </div>
                                                <div>
                                                  <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                                                </div>
                                                <blockquote
                                                  style="border:none;border-left:solid
                                                  #cccccc
                                                  1.0pt;padding:0in 0in
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6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
                                                  <div>
                                                    <div>
                                                      <p
                                                        class="MsoNormal"><b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">
                                                          Richard Smith
                                                          [mailto:<a
                                                          moz-do-not-send="true"
href="mailto:richard@metafoo.co.uk" target="_blank">richard@metafoo.co.uk</a>]
                                                          <br>
                                                          <b>Sent:</b>
                                                          Thursday,
                                                          August 31,
                                                          2017 2:09 PM<br>
                                                          <b>To:</b>
                                                          Kaylor, Andrew
                                                          <<a
                                                          moz-do-not-send="true"
href="mailto:andrew.kaylor@intel.com" target="_blank">andrew.kaylor@intel.com</a>><br>
                                                          <b>Cc:</b>
                                                          Marcus Johnson
                                                          <<a
                                                          moz-do-not-send="true"
href="mailto:bumblebritches57@gmail.com" target="_blank">bumblebritches57@gmail.com</a>>;
                                                          Clang Dev <<a
moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org"
                                                          target="_blank">cfe-dev@lists.llvm.org</a>>;
                                                          <a
                                                          moz-do-not-send="true"
href="mailto:wei.ding2@amd.com" target="_blank">wei.ding2@amd.com</a></span></p>
                                                      <div>
                                                        <div>
                                                          <p
                                                          class="MsoNormal"><br>
                                                          <b>Subject:</b>
                                                          Re: [cfe-dev]
                                                          Why is #pragma
                                                          STDC
                                                          FENV_ACCESS
                                                          not supported?</p>
                                                        </div>
                                                      </div>
                                                      <div>
                                                        <div>
                                                          <p
                                                          class="MsoNormal"> </p>
                                                          <div>
                                                          <div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal">On
                                                          31 August 2017
                                                          at 11:09,
                                                          Kaylor, Andrew
                                                          via cfe-dev
                                                          <<a
                                                          moz-do-not-send="true"
href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>>
                                                          wrote:</p>
                                                          <blockquote
                                                          style="border:none;border-left:solid
                                                          #cccccc
                                                          1.0pt;padding:0in
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6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
                                                          <div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">There
                                                          are still a
                                                          few things
                                                          missing from
                                                          the optimizer
                                                          to get it
                                                          completely
                                                          robust, but I
                                                          think there is
                                                          enough in
                                                          place for
                                                          front end work
                                                          to begin.  As
                                                          I think I’ve
                                                          demonstrated
                                                          in my recent
                                                          attempt to
                                                          contribute a
                                                          clang patch
                                                          I’m not
                                                          skilled enough
                                                          with the front
                                                          end to be the
                                                          person to pull
                                                          this off
                                                          without an
                                                          excessive
                                                          amount of
                                                          oversight, but
                                                          as Erich
                                                          indicated we
                                                          do have some
                                                          good front end
                                                          people here
                                                          who have this
                                                          on their TODO
                                                          list.  It’s
                                                          just not at
                                                          the top of the
                                                          TODO list yet.</span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">If
                                                          anyone is
                                                          interested in
                                                          the details of
                                                          the LLVM side
                                                          of things,
                                                          there are
                                                          constrained FP
                                                          intrinisics
                                                          (still marked
                                                          as
                                                          experimental
                                                          at this point)
                                                          documented in
                                                          the language
                                                          reference. 
                                                          The initial
                                                          patch can be
                                                          seen here:</span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><a
moz-do-not-send="true" href="https://reviews.llvm.org/D27028"
                                                          target="_blank">https://reviews.llvm.org/<wbr>D27028</a></span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">I’ve
                                                          since added
                                                          another group
                                                          of intrinsics
                                                          to handle the
libm-equivalent intrinsics, and more recently Wei Ding contributed an
                                                          fma intrinsic.</span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">The
                                                          idea is that
                                                          the front end
                                                          will emit the
                                                          constrained
                                                          intrinsics in
                                                          place of
                                                          equivalent
                                                          general FP
                                                          operations or
                                                          intrinsics in
                                                          scopes where
                                                          FENV_ACCESS is
                                                          enabled.  This
                                                          will prevent
                                                          the optimizer
                                                          from making
                                                          optimizations
                                                          that assume
                                                          default fenv
                                                          settings
                                                          (which is what
                                                          we want the
                                                          optimizer to
                                                          do in all
                                                          other cases). 
                                                          Eventually,
                                                          we’ll want to
                                                          go back and
                                                          teach specific
                                                          optimizations
                                                          to understand
                                                          the intrinsics
                                                          so that where
                                                          possible
                                                          optimizations
                                                          can be
                                                          performed in a
                                                          manner
                                                          consistent
                                                          with dynamic
                                                          rounding modes
                                                          and strict
                                                          exception
                                                          handling.</span></p>
                                                          </div>
                                                          </div>
                                                          </blockquote>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"> </p>
                                                          </div>
                                                          <div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">How do you deal with the hoisting-into-<span
class="m_1672052445564938120m-2075974219545047674m2724022782041152477gmail-il">fenv_access</span> <wbr>problem?
                                                          Eg:</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt"> </span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">double f(double a, double b, double c) {</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">  {</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">#pragma STDC <span
class="m_1672052445564938120m-2075974219545047674m2724022782041152477gmail-il">FENV_ACCESS</span> ON</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">    feenableexcept(FE_OVERFLOW);</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">    double d = a * b;</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">    fedisableexcept(FE_OVERFLOW);</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">  }</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">  return c * d;</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">}</span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt"> </span></p>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:9.5pt">What stops llvm from hoisting the second fmul up
                                                          to before the
fedisableexcept?</span></p>
                                                          </div>
                                                          </div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p>
                                                          </div>
                                                          <blockquote
                                                          style="border:none;border-left:solid
                                                          #cccccc
                                                          1.0pt;padding:0in
                                                          0in 0in
6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
                                                          <div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">-Andy</span></p>
                                                          <p
                                                          class="MsoNormal"><a
moz-do-not-send="true"
                                                          name="m_1672052445564938120_m_-2075974219545047674_m_272402278204115"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></a></p>
                                                          <div>
                                                          <div
                                                          style="border:none;border-top:solid
                                                          #e1e1e1
                                                          1.0pt;padding:3.0pt
                                                          0in 0in 0in">
                                                          <p
                                                          class="MsoNormal"><b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Hal
                                                          Finkel
                                                          [mailto:<a
                                                          moz-do-not-send="true"
href="mailto:hfinkel@anl.gov" target="_blank">hfinkel@anl.gov</a>]
                                                          <br>
                                                          <b>Sent:</b>
                                                          Thursday,
                                                          August 31,
                                                          2017 10:45 AM<br>
                                                          <b>To:</b>
                                                          Richard Smith
                                                          <<a
                                                          moz-do-not-send="true"
href="mailto:richard@metafoo.co.uk" target="_blank">richard@metafoo.co.uk</a>>;
                                                          Marcus Johnson
                                                          <<a
                                                          moz-do-not-send="true"
href="mailto:bumblebritches57@gmail.com" target="_blank">bumblebritches57@gmail.com</a>><br>
                                                          <b>Cc:</b>
                                                          Clang Dev <<a
moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org"
                                                          target="_blank">cfe-dev@lists.llvm.org</a>>;
                                                          Kaylor, Andrew
                                                          <<a
                                                          moz-do-not-send="true"
href="mailto:andrew.kaylor@intel.com" target="_blank">andrew.kaylor@intel.com</a>><br>
                                                          <b>Subject:</b>
                                                          Re: [cfe-dev]
                                                          Why is #pragma
                                                          STDC
                                                          FENV_ACCESS
                                                          not supported?</span></p>
                                                          </div>
                                                          </div>
                                                          <div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"> </p>
                                                          <p> </p>
                                                          <div>
                                                          <p
                                                          class="MsoNormal">On
                                                          08/31/2017
                                                          12:10 PM,
                                                          Richard Smith
                                                          via cfe-dev
                                                          wrote:</p>
                                                          </div>
                                                          <blockquote
                                                          style="margin-top:5.0pt;margin-bottom:5.0pt">
                                                          <div>
                                                          <p
                                                          class="MsoNormal">Because
                                                          no-one has
                                                          implemented
                                                          it. Patches
                                                          would be
                                                          welcome, but
                                                          will need to
                                                          start with a
                                                          design and
                                                          implementation
                                                          of the
                                                          requisite llvm
                                                          extensions.</p>
                                                          </div>
                                                          </blockquote>
                                                          <p
                                                          class="MsoNormal"
style="margin-bottom:12.0pt"><br>
                                                          Yes. This is
                                                          what Andrew
                                                          Kaylor has
                                                          been working
                                                          on (cc'd).<br>
                                                          <br>
                                                           -Hal</p>
                                                          <blockquote
                                                          style="margin-top:5.0pt;margin-bottom:5.0pt">
                                                          <div>
                                                          <p
                                                          class="MsoNormal"> </p>
                                                          <div>
                                                          <p
                                                          class="MsoNormal">On
                                                          31 Aug 2017
                                                          10:06, "Marcus
                                                          Johnson via
                                                          cfe-dev" <<a
moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org"
                                                          target="_blank">cfe-dev@lists.llvm.org</a>>
                                                          wrote:</p>
                                                          <blockquote
                                                          style="border:none;border-left:solid
                                                          #cccccc
                                                          1.0pt;padding:0in
                                                          0in 0in
6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt">
                                                          <div>
                                                          <div>
                                                          <p
                                                          class="MsoNormal"><span
style="font-size:18.0pt">^^^^^^</span></p>
                                                          </div>
                                                          </div>
                                                          <p
                                                          class="MsoNormal"
style="margin-bottom:12.0pt"><br>
______________________________<wbr>_________________<br>
                                                          cfe-dev
                                                          mailing list<br>
                                                          <a
                                                          moz-do-not-send="true"
href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a><br>
                                                          <a
                                                          moz-do-not-send="true"
href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev"
                                                          target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/cfe-dev</a></p>
                                                          </blockquote>
                                                          </div>
                                                          </div>
                                                          <p
                                                          class="MsoNormal"
style="margin-bottom:12.0pt"> </p>
                                                          <pre>______________________________<wbr>_________________</pre>
<pre>cfe-dev mailing list</pre>
<pre><a moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a></pre>
<pre><a moz-do-not-send="true" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/cfe-dev</a></pre>
</blockquote>
<p class="MsoNormal" style="margin-bottom:12.0pt"> </p>
<pre>-- </pre>
<pre>Hal Finkel</pre>
<pre>Lead, Compiler Technology and Programming Languages</pre>
<pre>Leadership Computing Facility</pre>
<pre>Argonne National Laboratory</pre>
</div>
</div>
</div>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt">

______________________________<wbr>_________________

cfe-dev mailing list

<a moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>

<a moz-do-not-send="true" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/cfe-dev</a></p>
</blockquote>
</div>
<p class="MsoNormal"> </p>
</div>
</div>
</div>
</div>
</div>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt">

______________________________<wbr>_________________

cfe-dev mailing list

<a moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>

<a moz-do-not-send="true" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/cfe-dev</a></p>
</blockquote>
</div>
<p class="MsoNormal"> </p>
</div>
</div>
</div>
</div>
</div>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt">

______________________________<wbr>_________________

cfe-dev mailing list

<a moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>

<a moz-do-not-send="true" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/cfe-dev</a></p>
</blockquote>
</div>
<p class="MsoNormal"> </p>
</div>
</div>
</div>
</div>
</div></div></div>
</div>


______________________________<wbr>_________________

cfe-dev mailing list

<a moz-do-not-send="true" href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>

<a moz-do-not-send="true" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" rel="noreferrer" target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/cfe-dev</a>


</blockquote></div>
</div></div>


<fieldset class="mimeAttachmentHeader"></fieldset>
<pre wrap="">_______________________________________________
cfe-dev mailing list
<a class="moz-txt-link-abbreviated" href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>
<a class="moz-txt-link-freetext" href="http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev">http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a>
</pre>

</blockquote>
<pre class="moz-signature" cols="72">-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory</pre></body></html>