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<pre><a name="line-1"></a><span class='hs-comment'>-- | Optimisation fuel is used to control the amount of work the optimiser does.</span>
<a name="line-2"></a><span class='hs-comment'>--</span>
<a name="line-3"></a><span class='hs-comment'>-- Every optimisation step consumes a certain amount of fuel and stops when</span>
<a name="line-4"></a><span class='hs-comment'>-- it runs out of fuel. This can be used e.g. to debug optimiser bugs: Run</span>
<a name="line-5"></a><span class='hs-comment'>-- the optimiser with varying amount of fuel to find out the exact number of</span>
<a name="line-6"></a><span class='hs-comment'>-- steps where a bug is introduced in the output.</span>
<a name="line-7"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-8"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>OptimizationFuel</span><span class='hs-layout'>,</span> <span class='hs-varid'>canRewriteWithFuel</span><span class='hs-layout'>,</span> <span class='hs-varid'>maybeRewriteWithFuel</span><span class='hs-layout'>,</span> <span class='hs-varid'>oneLessFuel</span>
<a name="line-9"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>OptFuelState</span><span class='hs-layout'>,</span> <span class='hs-varid'>initOptFuelState</span> <span class='hs-comment'>--, setTotalFuel</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>tankFilledTo</span><span class='hs-layout'>,</span> <span class='hs-varid'>diffFuel</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>FuelConsumer</span>
<a name="line-12"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>FuelUsingMonad</span><span class='hs-layout'>,</span> <span class='hs-conid'>FuelState</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>lastFuelPass</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuelExhausted</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuelRemaining</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuelDecrement</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuelDec1</span>
<a name="line-14"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>runFuelIO</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuelConsumingPass</span>
<a name="line-15"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>FuelMonad</span>
<a name="line-16"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>liftUniq</span>
<a name="line-17"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>lGraphOfGraph</span> <span class='hs-comment'>-- needs to be able to create a unique ID...</span>
<a name="line-18"></a> <span class='hs-layout'>)</span>
<a name="line-19"></a><span class='hs-keyword'>where</span>
<a name="line-20"></a>
<a name="line-21"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>BlockId</span>
<a name="line-22"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>ZipCfg</span>
<a name="line-23"></a><span class='hs-comment'>--import GHC.Exts (State#)</span>
<a name="line-24"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Panic</span>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span>
<a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span>
<a name="line-27"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>StaticFlags</span> <span class='hs-layout'>(</span><span class='hs-varid'>opt_Fuel</span><span class='hs-layout'>)</span>
<a name="line-28"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>UniqSupply</span>
<a name="line-29"></a>
<a name="line-30"></a><span class='hs-cpp'>#include "HsVersions.h"</span>
<a name="line-31"></a>
<a name="line-32"></a>
<a name="line-33"></a><a name="OptFuelState"></a><span class='hs-comment'>-- We limit the number of transactions executed using a record of flags</span>
<a name="line-34"></a><a name="OptFuelState"></a><span class='hs-comment'>-- stored in an HscEnv. The flags store the name of the last optimization</span>
<a name="line-35"></a><a name="OptFuelState"></a><span class='hs-comment'>-- pass and the amount of optimization fuel remaining.</span>
<a name="line-36"></a><a name="OptFuelState"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>OptFuelState</span> <span class='hs-keyglyph'>=</span>
<a name="line-37"></a> <span class='hs-conid'>OptFuelState</span> <span class='hs-layout'>{</span> <span class='hs-varid'>pass_ref</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-conid'>String</span>
<a name="line-38"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>fuel_ref</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-39"></a> <span class='hs-layout'>}</span>
<a name="line-40"></a><a name="initOptFuelState"></a><span class='hs-definition'>initOptFuelState</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-conid'>OptFuelState</span>
<a name="line-41"></a><span class='hs-definition'>initOptFuelState</span> <span class='hs-keyglyph'>=</span>
<a name="line-42"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>pass_ref'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>newIORef</span> <span class='hs-str'>"unoptimized program"</span>
<a name="line-43"></a> <span class='hs-varid'>fuel_ref'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>newIORef</span> <span class='hs-layout'>(</span><span class='hs-varid'>tankFilledTo</span> <span class='hs-varid'>opt_Fuel</span><span class='hs-layout'>)</span>
<a name="line-44"></a> <span class='hs-varid'>return</span> <span class='hs-conid'>OptFuelState</span> <span class='hs-layout'>{</span><span class='hs-varid'>pass_ref</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pass_ref'</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuel_ref</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fuel_ref'</span><span class='hs-layout'>}</span>
<a name="line-45"></a>
<a name="line-46"></a><a name="FuelConsumer"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>FuelConsumer</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>OptimizationFuel</span><span class='hs-layout'>)</span>
<a name="line-47"></a>
<a name="line-48"></a><a name="canRewriteWithFuel"></a><span class='hs-definition'>canRewriteWithFuel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-49"></a><a name="oneLessFuel"></a><span class='hs-definition'>oneLessFuel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-50"></a><a name="maybeRewriteWithFuel"></a><span class='hs-definition'>maybeRewriteWithFuel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span>
<a name="line-51"></a><a name="diffFuel"></a><span class='hs-definition'>diffFuel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-52"></a> <span class='hs-comment'>-- to measure consumption during compilation</span>
<a name="line-53"></a><a name="tankFilledTo"></a><span class='hs-definition'>tankFilledTo</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-54"></a>
<a name="line-55"></a><span class='hs-cpp'>#ifdef DEBUG</span>
<a name="line-56"></a><a name="OptimizationFuel"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-conid'>Int</span>
<a name="line-57"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Show</span>
<a name="line-58"></a>
<a name="line-59"></a><span class='hs-definition'>tankFilledTo</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-60"></a><span class='hs-definition'>canRewriteWithFuel</span> <span class='hs-layout'>(</span><span class='hs-conid'>OptimizationFuel</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span>
<a name="line-61"></a><span class='hs-definition'>maybeRewriteWithFuel</span> <span class='hs-varid'>fuel</span> <span class='hs-varid'>ma</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>canRewriteWithFuel</span> <span class='hs-varid'>fuel</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>ma</span> <span class='hs-keyword'>else</span> <span class='hs-conid'>Nothing</span>
<a name="line-62"></a><span class='hs-definition'>oneLessFuel</span> <span class='hs-layout'>(</span><span class='hs-conid'>OptimizationFuel</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ASSERT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>OptimizationFuel</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-63"></a><span class='hs-definition'>diffFuel</span> <span class='hs-layout'>(</span><span class='hs-conid'>OptimizationFuel</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>OptimizationFuel</span> <span class='hs-varid'>f'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-comment'>-</span> <span class='hs-varid'>f'</span>
<a name="line-64"></a><span class='hs-cpp'>#else</span>
<a name="line-65"></a><a name="OptimizationFuel"></a><span class='hs-comment'>-- type OptimizationFuel = State# () -- would like this, but it won't work</span>
<a name="line-66"></a><a name="OptimizationFuel"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-67"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Show</span>
<a name="line-68"></a><span class='hs-definition'>tankFilledTo</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>panic</span> <span class='hs-str'>"tankFilledTo"</span> <span class='hs-comment'>-- should be impossible to evaluate</span>
<a name="line-69"></a> <span class='hs-comment'>-- realWorld# might come in handy, too...</span>
<a name="line-70"></a><span class='hs-definition'>canRewriteWithFuel</span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>True</span>
<a name="line-71"></a><span class='hs-definition'>maybeRewriteWithFuel</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>ma</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ma</span>
<a name="line-72"></a><span class='hs-definition'>oneLessFuel</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span>
<a name="line-73"></a><span class='hs-definition'>diffFuel</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>0</span>
<a name="line-74"></a><span class='hs-cpp'>#endif</span>
<a name="line-75"></a>
<a name="line-76"></a><a name="FuelState"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>FuelState</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelState</span> <span class='hs-layout'>{</span> <span class='hs-varid'>fs_fuellimit</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>OptimizationFuel</span><span class='hs-layout'>,</span> <span class='hs-varid'>fs_lastpass</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-layout'>}</span>
<a name="line-77"></a><a name="FuelMonad"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-conid'>FuelState</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>UniqSM</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>FuelState</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-78"></a>
<a name="line-79"></a><a name="fuelConsumingPass"></a><span class='hs-definition'>fuelConsumingPass</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelConsumer</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>a</span>
<a name="line-80"></a><span class='hs-definition'>fuelConsumingPass</span> <span class='hs-varid'>name</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>fuel</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>fuelRemaining</span>
<a name="line-81"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuel'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>fuel</span>
<a name="line-82"></a> <span class='hs-varid'>fuelDecrement</span> <span class='hs-varid'>name</span> <span class='hs-varid'>fuel</span> <span class='hs-varid'>fuel'</span>
<a name="line-83"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span>
<a name="line-84"></a>
<a name="line-85"></a><a name="runFuelIO"></a><span class='hs-definition'>runFuelIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>OptFuelState</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span>
<a name="line-86"></a><span class='hs-definition'>runFuelIO</span> <span class='hs-varid'>fs</span> <span class='hs-layout'>(</span><span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-87"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>pass</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readIORef</span> <span class='hs-layout'>(</span><span class='hs-varid'>pass_ref</span> <span class='hs-varid'>fs</span><span class='hs-layout'>)</span>
<a name="line-88"></a> <span class='hs-varid'>fuel</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readIORef</span> <span class='hs-layout'>(</span><span class='hs-varid'>fuel_ref</span> <span class='hs-varid'>fs</span><span class='hs-layout'>)</span>
<a name="line-89"></a> <span class='hs-varid'>u</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>mkSplitUniqSupply</span> <span class='hs-chr'>'u'</span>
<a name="line-90"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>FuelState</span> <span class='hs-varid'>fuel'</span> <span class='hs-varid'>pass'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>initUs_</span> <span class='hs-varid'>u</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>FuelState</span> <span class='hs-varid'>fuel</span> <span class='hs-varid'>pass</span><span class='hs-layout'>)</span>
<a name="line-91"></a> <span class='hs-varid'>writeIORef</span> <span class='hs-layout'>(</span><span class='hs-varid'>pass_ref</span> <span class='hs-varid'>fs</span><span class='hs-layout'>)</span> <span class='hs-varid'>pass'</span>
<a name="line-92"></a> <span class='hs-varid'>writeIORef</span> <span class='hs-layout'>(</span><span class='hs-varid'>fuel_ref</span> <span class='hs-varid'>fs</span><span class='hs-layout'>)</span> <span class='hs-varid'>fuel'</span>
<a name="line-93"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span>
<a name="line-94"></a>
<a name="line-95"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-keyword'>where</span>
<a name="line-96"></a> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>f</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>s'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>f</span> <span class='hs-varid'>s</span>
<a name="line-97"></a> <span class='hs-keyword'>let</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>f'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>k</span> <span class='hs-varid'>a</span> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>f'</span> <span class='hs-varid'>s'</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-98"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-99"></a>
<a name="line-100"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadUnique</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-keyword'>where</span>
<a name="line-101"></a> <span class='hs-varid'>getUniqueSupplyM</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftUniq</span> <span class='hs-varid'>getUniqueSupplyM</span>
<a name="line-102"></a> <span class='hs-varid'>getUniqueM</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftUniq</span> <span class='hs-varid'>getUniqueM</span>
<a name="line-103"></a> <span class='hs-varid'>getUniquesM</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftUniq</span> <span class='hs-varid'>getUniquesM</span>
<a name="line-104"></a><a name="liftUniq"></a><span class='hs-definition'>liftUniq</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>UniqSM</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>x</span>
<a name="line-105"></a><span class='hs-definition'>liftUniq</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span> <span class='hs-varop'>>>=</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>u</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>u</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-106"></a>
<a name="line-107"></a><a name="FuelUsingMonad"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>FuelUsingMonad</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-108"></a> <span class='hs-varid'>fuelRemaining</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-conid'>OptimizationFuel</span>
<a name="line-109"></a> <span class='hs-varid'>fuelDecrement</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-110"></a> <span class='hs-varid'>fuelDec1</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-111"></a> <span class='hs-varid'>fuelExhausted</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-conid'>Bool</span>
<a name="line-112"></a> <span class='hs-varid'>lastFuelPass</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-conid'>String</span>
<a name="line-113"></a>
<a name="line-114"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>FuelUsingMonad</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-keyword'>where</span>
<a name="line-115"></a> <span class='hs-varid'>fuelRemaining</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>extract</span> <span class='hs-varid'>fs_fuellimit</span>
<a name="line-116"></a> <span class='hs-varid'>lastFuelPass</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>extract</span> <span class='hs-varid'>fs_lastpass</span>
<a name="line-117"></a> <span class='hs-varid'>fuelExhausted</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>extract</span> <span class='hs-varop'>$</span> <span class='hs-varid'>not</span> <span class='hs-varop'>.</span> <span class='hs-varid'>canRewriteWithFuel</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fs_fuellimit</span>
<a name="line-118"></a> <span class='hs-varid'>fuelDecrement</span> <span class='hs-varid'>p</span> <span class='hs-varid'>f</span> <span class='hs-varid'>f'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>()</span><span class='hs-layout'>,</span> <span class='hs-varid'>fuelDecrementState</span> <span class='hs-varid'>p</span> <span class='hs-varid'>f</span> <span class='hs-varid'>f'</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-119"></a> <span class='hs-varid'>fuelDec1</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>f</span>
<a name="line-120"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>f</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>canRewriteWithFuel</span> <span class='hs-layout'>(</span><span class='hs-varid'>fs_fuellimit</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>then</span>
<a name="line-121"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>()</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span> <span class='hs-layout'>{</span> <span class='hs-varid'>fs_fuellimit</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>oneLessFuel</span> <span class='hs-layout'>(</span><span class='hs-varid'>fs_fuellimit</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-layout'>}</span><span class='hs-layout'>)</span>
<a name="line-122"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>panic</span> <span class='hs-str'>"Tried to use exhausted fuel supply"</span>
<a name="line-123"></a>
<a name="line-124"></a><a name="extract"></a><span class='hs-definition'>extract</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>FuelState</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelMonad</span> <span class='hs-varid'>a</span>
<a name="line-125"></a><span class='hs-definition'>extract</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>s</span><span class='hs-layout'>,</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-126"></a>
<a name="line-127"></a><a name="fuelDecrementState"></a><span class='hs-definition'>fuelDecrementState</span>
<a name="line-128"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OptimizationFuel</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelState</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelState</span>
<a name="line-129"></a><span class='hs-definition'>fuelDecrementState</span> <span class='hs-varid'>new_optimizer</span> <span class='hs-varid'>old</span> <span class='hs-varid'>new</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span>
<a name="line-130"></a> <span class='hs-conid'>FuelState</span> <span class='hs-layout'>{</span> <span class='hs-varid'>fs_fuellimit</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lim</span><span class='hs-layout'>,</span> <span class='hs-varid'>fs_lastpass</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>optimizer</span> <span class='hs-layout'>}</span>
<a name="line-131"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>lim</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>diffFuel</span> <span class='hs-varid'>old</span> <span class='hs-layout'>(</span><span class='hs-varid'>fs_fuellimit</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>new</span>
<a name="line-132"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>panic</span> <span class='hs-varop'>$</span>
<a name="line-133"></a> <span class='hs-varid'>concat</span> <span class='hs-keyglyph'>[</span><span class='hs-str'>"lost track of "</span><span class='hs-layout'>,</span> <span class='hs-varid'>new_optimizer</span><span class='hs-layout'>,</span> <span class='hs-str'>"'s transactions"</span><span class='hs-keyglyph'>]</span>
<a name="line-134"></a> <span class='hs-varid'>optimizer</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>diffFuel</span> <span class='hs-varid'>old</span> <span class='hs-varid'>new</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>new_optimizer</span> <span class='hs-keyword'>else</span> <span class='hs-varid'>fs_lastpass</span> <span class='hs-varid'>s</span>
<a name="line-135"></a>
<a name="line-136"></a><a name="lGraphOfGraph"></a><span class='hs-comment'>-- lGraphOfGraph is here because we need uniques to implement it.</span>
<a name="line-137"></a><span class='hs-definition'>lGraphOfGraph</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Graph</span> <span class='hs-varid'>m</span> <span class='hs-varid'>l</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FuelMonad</span> <span class='hs-layout'>(</span><span class='hs-conid'>LGraph</span> <span class='hs-varid'>m</span> <span class='hs-varid'>l</span><span class='hs-layout'>)</span>
<a name="line-138"></a><span class='hs-definition'>lGraphOfGraph</span> <span class='hs-layout'>(</span><span class='hs-conid'>Graph</span> <span class='hs-varid'>tail</span> <span class='hs-varid'>blocks</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-139"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>entry</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>liftM</span> <span class='hs-conid'>BlockId</span> <span class='hs-varop'>$</span> <span class='hs-varid'>getUniqueM</span>
<a name="line-140"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>LGraph</span> <span class='hs-varid'>entry</span> <span class='hs-layout'>(</span><span class='hs-varid'>insertBlock</span> <span class='hs-layout'>(</span><span class='hs-conid'>Block</span> <span class='hs-varid'>entry</span> <span class='hs-varid'>tail</span><span class='hs-layout'>)</span> <span class='hs-varid'>blocks</span><span class='hs-layout'>)</span>
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