102 lines
3.8 KiB
Plaintext
102 lines
3.8 KiB
Plaintext
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#!/bin/bash
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#
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# findoptdiff
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#
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# This script helps find the optimization difference between two llvm
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# builds. It is useful when you have a build that is known to work and
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# one that exhibits an optimization problem. Identifying the difference
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# between the two builds can lead to discovery of the source of a
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# mis-optimization.
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#
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# The script takes two llvm build paths as arguments. These specify the
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# the two llvm builds to compare. It is generally expected that they
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# are "close cousins". That is, they are the same except that the
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# second build contains some experimental optimization features that
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# are suspected of producing a misoptimization.
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#
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# The script takes two bitcode files, one from each build. They are
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# presumed to be a compilation of the same program or program fragment
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# with the only difference being the builds.
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#
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# The script operates by iteratively applying the optimizations that gccas
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# and gccld run until there is a difference in the assembly resulting
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# from the optimization. The difference is then reported with the set of
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# optimization passes that produce the difference. The processing
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# continues until all optimization passes have been tried. The differences
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# for each pass, if they do differ, are placed in a diffs.# file.
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#
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# To work around differences in the assembly language format, the script
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# can also take two filter arguments that post-process the assembly
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# so they can be differenced without making false positives for known
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# differences in the two builds. These filters are optional.
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#
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# Usage:
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# findoptdiff llvm1 llvm2 bc1 bc2 filter1 filter2
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#
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# Where:
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# llvm1
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# is the path to the first llvm build dir
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# llvm2
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# is the path to the second llvm build dir
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# bc1
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# is the bitcode file for the first llvm environment
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# bc2
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# is the bitcode file for the second llvm environment
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# filter1
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# is an optional filter for filtering the llvm1 generated assembly
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# filter2
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# is an optional filter for filtering the llvm2 generated assembly
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#
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llvm1=$1
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llvm2=$2
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bc1=$3
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bc2=$4
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filt1=$5
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filt2=$6
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if [ -z "$filt1" ] ; then
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filt1="cat"
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fi
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if [ -z "$filt2" ] ; then
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filt2="cat"
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fi
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opt1="${bc1}.opt"
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opt2="${bc2}.opt"
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ll1="${bc1}.ll"
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ll2="${bc2}.ll"
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opt1ll="${bc1}.opt.ll"
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opt2ll="${bc2}.opt.ll"
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dis1="$llvm1/Debug/bin/llvm-dis"
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dis2="$llvm2/Debug/bin/llvm-dis"
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opt1="$llvm1/Debug/bin/opt"
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opt2="$llvm2/Debug/bin/opt"
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all_switches="-verify -lowersetjmp -simplifycfg -mem2reg -globalopt -globaldce -ipconstprop -deadargelim -instcombine -simplifycfg -prune-eh -inline -simplify-libcalls -argpromotion -tailduplicate -simplifycfg -scalarrepl -instcombine -predsimplify -condprop -tailcallelim -simplifycfg -reassociate -licm -loop-unswitch -instcombine -indvars -loop-unroll -instcombine -load-vn -gcse -sccp -instcombine -condprop -dse -dce -simplifycfg -deadtypeelim -constmerge -internalize -ipsccp -globalopt -constmerge -deadargelim -inline -prune-eh -globalopt -globaldce -argpromotion -instcombine -predsimplify -scalarrepl -globalsmodref-aa -licm -load-vn -gcse -dse -instcombine -simplifycfg -verify"
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#counter=0
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function tryit {
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switches_to_use="$1"
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$opt1 $switches_to_use "$bc1" -o - | $dis1 | $filt1 > "$opt1ll"
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$opt2 $switches_to_use "$bc2" -o - | $dis2 | $filt2 > "$opt2ll"
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diffs="diffs."$((counter++))
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diff "$opt1ll" "$opt2ll" > $diffs
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if [ $? -ne 0 ] ; then
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echo
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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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head $diffs
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echo 'Switches:' $switches_to_use >> $diffs
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else
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rm $diffs
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fi
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return 1
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}
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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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