llvm-project

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#!/bin/bash
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#
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#  findmisopt
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#
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#      This is a quick and dirty hack to potentially find a misoptimization
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#      problem. Mostly its to work around problems in bugpoint that prevent
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#      it from finding a problem unless the set of failing optimizations are
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#      known and given to it on the command line.
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#
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#      Given a bitcode file that produces correct output (or return code), 
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#      this script will run through all the optimizations passes that gccas
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#      uses (in the same order) and will narrow down which optimizations
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#      cause the program either generate different output or return a 
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#      different result code. When the passes have been narrowed down, 
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#      bugpoint is invoked to further refine the problem to its origin. If a
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#      release version of bugpoint is available it will be used, otherwise 
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#      debug.
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#
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#   Usage:
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#      findmisopt bcfile outdir progargs [match]
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#
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#   Where:
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#      bcfile 
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#          is the bitcode file input (the unoptimized working case)
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#      outdir
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#          is a directory into which intermediate results are placed
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#      progargs
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#          is a single argument containing all the arguments the program needs
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#      proginput
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#          is a file name from which stdin should be directed
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#      match
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#          if specified to any value causes the result code of the program to
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#          be used to determine success/fail. If not specified success/fail is
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#          determined by diffing the program's output with the non-optimized
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#          output.
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#       
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if [ "$#" -lt 3 ] ; then
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  echo "usage: findmisopt bcfile outdir progargs [match]"
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  exit 1
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fi
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dir="${0%%/utils/findmisopt}"
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if [ -x "$dir/Release/bin/bugpoint" ] ; then
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  bugpoint="$dir/Release/bin/bugpoint"
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elif [ -x "$dir/Debug/bin/bugpoint" ] ; then
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  bugpoint="$dir/Debug/bin/bugpoint"
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else
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  echo "findmisopt: bugpoint not found"
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  exit 1
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fi
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bcfile="$1"
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outdir="$2"
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args="$3"
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input="$4"
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if [ ! -f "$input" ] ; then
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  input="/dev/null"
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fi
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match="$5"
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name=`basename $bcfile .bc`
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ll="$outdir/${name}.ll"
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s="$outdir/${name}.s"
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prog="$outdir/${name}"
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out="$outdir/${name}.out"
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optbc="$outdir/${name}.opt.bc"
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optll="$outdir/${name}.opt.ll"
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opts="$outdir/${name}.opt.s"
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optprog="$outdir/${name}.opt"
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optout="$outdir/${name}.opt.out"
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ldflags="-lstdc++ -lm -ldl -lc"
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echo "Test Name: $name"
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echo "Unoptimized program: $prog"
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echo "  Optimized program: $optprog"
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# Define the list of optimizations to run. This comprises the same set of 
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# optimizations that opt -O3 runs, in the same order.
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opt_switches=`llvm-as < /dev/null -o - | opt -O3 -disable-output -debug-pass=Arguments 2>&1 | sed 's/Pass Arguments: //'`
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all_switches="$opt_switches"
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echo "Passes : $all_switches"
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# Create output directory if it doesn't exist
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if [ -f "$outdir" ] ; then
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  echo "$outdir is not a directory"
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  exit 1
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fi
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if [ ! -d "$outdir" ] ; then
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  mkdir "$outdir" || exit 1
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fi
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# Generate the disassembly
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llvm-dis "$bcfile" -o "$ll" -f || exit 1
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# Generate the non-optimized program and its output
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llc "$bcfile" -o "$s" -f || exit 1
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gcc "$s" -o "$prog" $ldflags || exit 1
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"$prog" $args > "$out" 2>&1 <$input
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ex1=$?
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# Current set of switches is empty
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function tryit {
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  switches_to_use="$1"
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  opt $switches_to_use "$bcfile" -o "$optbc" -f || exit
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  llvm-dis "$optbc" -o "$optll" -f || exit
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  llc "$optbc" -o "$opts" -f || exit
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  gcc "$opts" -o "$optprog" $ldflags || exit
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  "$optprog" $args > "$optout" 2>&1 <"$input"
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  ex2=$?
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  if [ -n "$match" ] ; then
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    if [ "$ex1" -ne "$ex2" ] ; then
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      echo "Return code not the same with these switches:"
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      echo $switches
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      echo "Unoptimized returned: $ex1"
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      echo "Optimized   returned: $ex2"
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      return 0
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    fi
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  else
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    diff "$out" "$optout" > /dev/null
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    if [ $? -ne 0 ] ; then
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      echo "Diff fails with these switches:"
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      echo $switches
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      echo "Differences:"
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      diff "$out" "$optout" | head
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      return 0;
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    fi
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  fi
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  return 1
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}
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echo "Trying to find optimization that breaks program:"
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for sw in $all_switches ; do
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  echo -n " $sw"
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  switches="$switches $sw"
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  if tryit "$switches" ; then
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    break;
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  fi
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done
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# Terminate the previous output with a newline
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echo ""
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# Determine if we're done because none of the optimizations broke the program
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if [ "$switches" == " $all_switches" ] ; then
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  echo "The program did not miscompile"
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  exit 0
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fi
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final=""
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while [ ! -z "$switches" ] ; do
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  trimmed=`echo "$switches" | sed -e 's/^ *\(-[^ ]*\).*/\1/'`
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  switches=`echo "$switches" | sed -e 's/^ *-[^ ]* *//'`
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  echo "Trimmed $trimmed from left"
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  tryit "$final $switches"
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  if [ "$?" -eq "0" ] ; then
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    echo "Still Failing .. continuing ..."
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    continue
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  else
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    echo "Found required early pass: $trimmed"
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    final="$final $trimmed"
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    continue
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  fi
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  echo "Next Loop"
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done
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if [ "$final" == " $all_switches" ] ; then
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  echo "findmisopt: All optimizations pass. Perhaps this isn't a misopt?"
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  exit 0
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fi
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echo "Smallest Optimization list=$final"
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bpcmd="$bugpoint -run-llc -disable-loop-extraction --output "$out" --input /dev/null $bcfile $final --args $args"
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echo "Running: $bpcmd"
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$bpcmd
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echo "findmisopt finished."
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