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remove some dead passes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83717 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
parent
39c0e67a89
commit
60f034097e
113
docs/Passes.html
113
docs/Passes.html
@ -78,7 +78,6 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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<tr><td><a href="#anders-aa">-anders-aa</a></td><td>Andersen's Interprocedural Alias Analysis</td></tr>
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<tr><td><a href="#basicaa">-basicaa</a></td><td>Basic Alias Analysis (default AA impl)</td></tr>
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<tr><td><a href="#basiccg">-basiccg</a></td><td>Basic CallGraph Construction</td></tr>
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<tr><td><a href="#basicvn">-basicvn</a></td><td>Basic Value Numbering (default GVN impl)</td></tr>
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<tr><td><a href="#codegenprepare">-codegenprepare</a></td><td>Optimize for code generation</td></tr>
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<tr><td><a href="#count-aa">-count-aa</a></td><td>Count Alias Analysis Query Responses</td></tr>
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<tr><td><a href="#debug-aa">-debug-aa</a></td><td>AA use debugger</td></tr>
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@ -90,7 +89,6 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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<tr><td><a href="#globalsmodref-aa">-globalsmodref-aa</a></td><td>Simple mod/ref analysis for globals</td></tr>
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<tr><td><a href="#instcount">-instcount</a></td><td>Counts the various types of Instructions</td></tr>
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<tr><td><a href="#intervals">-intervals</a></td><td>Interval Partition Construction</td></tr>
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<tr><td><a href="#load-vn">-load-vn</a></td><td>Load Value Numbering</td></tr>
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<tr><td><a href="#loops">-loops</a></td><td>Natural Loop Construction</td></tr>
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<tr><td><a href="#memdep">-memdep</a></td><td>Memory Dependence Analysis</td></tr>
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<tr><td><a href="#no-aa">-no-aa</a></td><td>No Alias Analysis (always returns 'may' alias)</td></tr>
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@ -125,11 +123,9 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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<tr><td><a href="#deadtypeelim">-deadtypeelim</a></td><td>Dead Type Elimination</td></tr>
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<tr><td><a href="#die">-die</a></td><td>Dead Instruction Elimination</td></tr>
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<tr><td><a href="#dse">-dse</a></td><td>Dead Store Elimination</td></tr>
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<tr><td><a href="#gcse">-gcse</a></td><td>Global Common Subexpression Elimination</td></tr>
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<tr><td><a href="#globaldce">-globaldce</a></td><td>Dead Global Elimination</td></tr>
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<tr><td><a href="#globalopt">-globalopt</a></td><td>Global Variable Optimizer</td></tr>
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<tr><td><a href="#gvn">-gvn</a></td><td>Global Value Numbering</td></tr>
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<tr><td><a href="#gvnpre">-gvnpre</a></td><td>Global Value Numbering/Partial Redundancy Elimination</td></tr>
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<tr><td><a href="#indmemrem">-indmemrem</a></td><td>Indirect Malloc and Free Removal</td></tr>
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<tr><td><a href="#indvars">-indvars</a></td><td>Canonicalize Induction Variables</td></tr>
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<tr><td><a href="#inline">-inline</a></td><td>Function Integration/Inlining</td></tr>
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@ -161,7 +157,6 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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<tr><td><a href="#mem2reg">-mem2reg</a></td><td>Promote Memory to Register</td></tr>
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<tr><td><a href="#memcpyopt">-memcpyopt</a></td><td>Optimize use of memcpy and friends</td></tr>
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<tr><td><a href="#mergereturn">-mergereturn</a></td><td>Unify function exit nodes</td></tr>
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<tr><td><a href="#predsimplify">-predsimplify</a></td><td>Predicate Simplifier</td></tr>
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<tr><td><a href="#prune-eh">-prune-eh</a></td><td>Remove unused exception handling info</td></tr>
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<tr><td><a href="#raiseallocs">-raiseallocs</a></td><td>Raise allocations from calls to instructions</td></tr>
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<tr><td><a href="#reassociate">-reassociate</a></td><td>Reassociate expressions</td></tr>
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@ -302,25 +297,6 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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<p>Yet to be written.</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="basicvn">Basic Value Numbering (default Value Numbering impl)</a>
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</div>
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<div class="doc_text">
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<p>
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This is the default implementation of the <code>ValueNumbering</code>
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interface. It walks the SSA def-use chains to trivially identify
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lexically identical expressions. This does not require any ahead of time
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analysis, so it is a very fast default implementation.
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</p>
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<p>
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The ValueNumbering analysis passes are mostly deprecated. They are only used
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by the <a href="#gcse">Global Common Subexpression Elimination pass</a>, which
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is deprecated by the <a href="#gvn">Global Value Numbering pass</a> (which
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does its value numbering on its own).
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="codegenprepare">Optimize for code generation</a>
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@ -459,28 +435,6 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="load-vn">Load Value Numbering</a>
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</div>
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<div class="doc_text">
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<p>
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This pass value numbers load and call instructions. To do this, it finds
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lexically identical load instructions, and uses alias analysis to determine
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which loads are guaranteed to produce the same value. To value number call
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instructions, it looks for calls to functions that do not write to memory
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which do not have intervening instructions that clobber the memory that is
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read from.
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</p>
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<p>
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This pass builds off of another value numbering pass to implement value
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numbering for non-load and non-call instructions. It uses Alias Analysis so
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that it can disambiguate the load instructions. The more powerful these base
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analyses are, the more powerful the resultant value numbering will be.
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="loops">Natural Loop Construction</a>
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@ -863,23 +817,6 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="gcse">Global Common Subexpression Elimination</a>
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</div>
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<div class="doc_text">
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<p>
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This pass is designed to be a very quick global transformation that
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eliminates global common subexpressions from a function. It does this by
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using an existing value numbering analysis pass to identify the common
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subexpressions, eliminating them when possible.
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</p>
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<p>
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This pass is deprecated by the <a href="#gvn">Global Value Numbering pass</a>
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(which does a better job with its own value numbering).
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="globaldce">Dead Global Elimination</a>
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@ -912,35 +849,11 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !
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</div>
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<div class="doc_text">
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<p>
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This pass performs global value numbering to eliminate fully redundant
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instructions. It also performs simple dead load elimination.
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</p>
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<p>
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Note that this pass does the value numbering itself, it does not use the
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ValueNumbering analysis passes.
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This pass performs global value numbering to eliminate fully and partially
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redundant instructions. It also performs redundant load elimination.
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="gvnpre">Global Value Numbering/Partial Redundancy Elimination</a>
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</div>
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<div class="doc_text">
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<p>
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This pass performs a hybrid of global value numbering and partial redundancy
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elimination, known as GVN-PRE. It performs partial redundancy elimination on
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values, rather than lexical expressions, allowing a more comprehensive view
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the optimization. It replaces redundant values with uses of earlier
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occurences of the same value. While this is beneficial in that it eliminates
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unneeded computation, it also increases register pressure by creating large
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live ranges, and should be used with caution on platforms that are very
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sensitive to register pressure.
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</p>
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<p>
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Note that this pass does the value numbering itself, it does not use the
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ValueNumbering analysis passes.
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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@ -1576,28 +1489,6 @@ if (X < 3) {</pre>
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</p>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="predsimplify">Predicate Simplifier</a>
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</div>
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<div class="doc_text">
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<p>
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Path-sensitive optimizer. In a branch where <tt>x == y</tt>, replace uses of
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<tt>x</tt> with <tt>y</tt>. Permits further optimization, such as the
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elimination of the unreachable call:
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</p>
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<blockquote><pre
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>void test(int *p, int *q)
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{
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if (p != q)
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return;
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if (*p != *q)
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foo(); // unreachable
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}</pre></blockquote>
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</div>
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<!-------------------------------------------------------------------------- -->
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<div class="doc_subsection">
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<a name="prune-eh">Remove unused exception handling info</a>
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