commit f067d584a81ae771d301304ea885e55e2de8ee9a
author Chris Lattner <sabre@nondot.org> Mon Feb 07 16:40:21 2011 +0000
committer Chris Lattner <sabre@nondot.org> Mon Feb 07 16:40:21 2011 +0000
tree 9e3fa2842b0884048e3cf0937db440d77d115168
parent 163a84bbce69947aa314760e6068c704fc0df7a0

implement .ll and .bc support for nsw/nuw on shl and exact on lshr/ashr.
Factor some code better.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125006 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LangRef.html

diff --git a/docs/LangRef.html b/docs/LangRef.html
index f799749..dbe3853 100644
--- a/docs/LangRef.html
+++ b/docs/LangRef.html
@@ -3684,7 +3684,10 @@
 
 <h5>Syntax:</h5>
 <pre>
-  &lt;result&gt; = shl &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;   <i>; yields {ty}:result</i>
+  &lt;result&gt; = shl &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;           <i>; yields {ty}:result</i>
+  &lt;result&gt; = shl nuw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;       <i>; yields {ty}:result</i>
+  &lt;result&gt; = shl nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;       <i>; yields {ty}:result</i>
+  &lt;result&gt; = shl nuw nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;   <i>; yields {ty}:result</i>
 </pre>
 
 <h5>Overview:</h5>
@@ -3704,6 +3707,14 @@
    vectors, each vector element of <tt>op1</tt> is shifted by the corresponding
    shift amount in <tt>op2</tt>.</p>
 
+<p>If the <tt>nuw</tt> keyword is present, then the shift produces a 
+   <a href="#trapvalues">trap value</a> if it shifts out any non-zero bits.  If
+   the <tt>nsw</tt> keywrod is present, then the shift produces a
+   <a href="#trapvalues">trap value</a> if it shifts out any bits that disagree
+   with the resultant sign bit.  As such, NUW/NSW have the same semantics as
+   they would if the shift were expressed as a mul instruction with the same
+   nsw/nuw bits in (mul %op1, (shl 1, %op2)).</p>
+
 <h5>Example:</h5>
 <pre>
   &lt;result&gt; = shl i32 4, %var   <i>; yields {i32}: 4 &lt;&lt; %var</i>
@@ -3723,7 +3734,8 @@
 
 <h5>Syntax:</h5>
 <pre>
-  &lt;result&gt; = lshr &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;   <i>; yields {ty}:result</i>
+  &lt;result&gt; = lshr &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;         <i>; yields {ty}:result</i>
+  &lt;result&gt; = lshr exact &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;   <i>; yields {ty}:result</i>
 </pre>
 
 <h5>Overview:</h5>
@@ -3743,6 +3755,11 @@
    vectors, each vector element of <tt>op1</tt> is shifted by the corresponding
    shift amount in <tt>op2</tt>.</p>
 
+<p>If the <tt>exact</tt> keyword is present, the result value of the
+   <tt>lshr</tt> is a <a href="#trapvalues">trap value</a> if any of the bits
+   shifted out are non-zero.</p>
+
+
 <h5>Example:</h5>
 <pre>
   &lt;result&gt; = lshr i32 4, 1   <i>; yields {i32}:result = 2</i>
@@ -3762,7 +3779,8 @@
 
 <h5>Syntax:</h5>
 <pre>
-  &lt;result&gt; = ashr &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;   <i>; yields {ty}:result</i>
+  &lt;result&gt; = ashr &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;         <i>; yields {ty}:result</i>
+  &lt;result&gt; = ashr exact &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt;   <i>; yields {ty}:result</i>
 </pre>
 
 <h5>Overview:</h5>
@@ -3783,6 +3801,10 @@
    the arguments are vectors, each vector element of <tt>op1</tt> is shifted by
    the corresponding shift amount in <tt>op2</tt>.</p>
 
+<p>If the <tt>exact</tt> keyword is present, the result value of the
+   <tt>ashr</tt> is a <a href="#trapvalues">trap value</a> if any of the bits
+   shifted out are non-zero.</p>
+
 <h5>Example:</h5>
 <pre>
   &lt;result&gt; = ashr i32 4, 1   <i>; yields {i32}:result = 2</i>