Changes in directory llvm/utils:
findoptdiff added (r1.1)
---
Log message:
Provide a script that can track down which optimization pass causes
different code to be produced between two llvm builds that differe slightly.
This is useful in tracking down mis-optimization bugs.
---
Diffs of the changes: (+99 -0)
findoptdiff | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 99 insertions(+)
Index: llvm/utils/findoptdiff
diff -c /dev/null llvm/utils/findoptdiff:1.1
*** /dev/null Mon Dec 11 11:42:22 2006
--- llvm/utils/findoptdiff Mon Dec 11 11:42:12 2006
***************
*** 0 ****
--- 1,99 ----
+ #!/bin/bash
+ #
+ # findoptdiff
+ #
+ # This script helps find the optimization difference between two llvm
+ # builds. It is useful when you have a build that is known to work and
+ # one that exhibits an optimization problem. Identifying the difference
+ # between the two builds can lead to discovery of the source of a
+ # mis-optimization.
+ #
+ # The script takes two llvm build paths as arguments. These specify the
+ # the two llvm builds to compare. It is generally expected that they
+ # are "close cousins". That is, they are the same except that the
+ # second build contains some experimental optimization features that
+ # are suspected of producing a misoptimization.
+ #
+ # The script takes two bytecode files, one from each build. They are
+ # presumed to be a compilation of the same program or program fragment
+ # with the only difference being the builds.
+ #
+ # The script operates by iteratively applying the optimizations that
gccas
+ # and gccld run until there is a difference in the assembly resulting
+ # from the optimization. The difference is then reported with the set of
+ # optimization passes that produce the difference.
+ #
+ # To work around differences in the assembly language format, the script
+ # can also take two filter arguments that post-process the assembly
+ # so they can be differenced without making false positives for known
+ # differences in the two builds. These filters are optional.
+ #
+ # Usage:
+ # findoptdiff llvm1 llvm2 bc1 bc2 filter1 filter2
+ #
+ # Where:
+ # llvm1
+ # is the path to the first llvm build dir
+ # llvm2
+ # is the path to the second llvm build dir
+ # bc1
+ # is the bytecode file for the first llvm environment
+ # bc2
+ # is the bytecode file for the second llvm environment
+ # filter1
+ # is an optional filter for filtering the llvm1 generated assembly
+ # filter2
+ # is an optional filter for filtering the llvm2 generated assembly
+ #
+ llvm1=$1
+ llvm2=$2
+ bc1=$3
+ bc2=$4
+ filt1=$5
+ if [ -z "$filt1" ] ; then
+ filt1="cat"
+ fi
+ filt2=$6
+ if [ -z "$filt2" ] ; then
+ filt2="cat"
+ fi
+ opt1=opt.$bc1
+ opt2=opt.$bc2
+ ll1=${bc1}.ll
+ ll2=${bc2}.ll
+ dir1="/proj/llvm/llvm-test-1/External/SPEC/CINT2000/300.twolf"
+ opt1="/proj/llvm/llvm-1/Debug/bin/opt"
+ dis1="/proj/llvm/llvm-1/Debug/bin/llvm-dis"
+ dir2="/proj/llvm/llvm-test-2/External/SPEC/CINT2000/300.twolf"
+ opt2="/proj/llvm/llvm-2/Debug/bin/opt"
+ dis2="/proj/llvm/llvm-2/Debug/bin/llvm-dis"
+ bcfile="Output/300.twolf.linked.rbc"
+ optll="opt.ll"
+
+ all_switches="-verify -lowersetjmp -funcresolve -raiseallocs -simplifycfg
-mem2reg -globalopt -globaldce -ipconstprop -deadargelim -instcombine
-simplifycfg -prune-eh -inline -simplify-libcalls -argpromotion -raise
-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 -funcresolve -internalize
-ipsccp -globalopt -constmerge -deadargelim -inline -prune-eh -globalopt
-globaldce -argpromotion -instcombine -predsimplify -scalarrepl
-globalsmodref-aa -licm -load-vn -gcse -dse -instcombine -simplifycfg -verify"
+
+ function tryit {
+ switches_to_use="$1"
+ cd $dir1
+ $opt1 $switches_to_use "$bcfile" -o - | $dis1 | $filt1 > "$optll"
+ cd $dir2
+ $opt2 $switches_to_use "$bcfile" -o - | $dis2 | $filt2 > "$optll"
+ diff "$dir1/$optll" "$dir2/$optll" > /dev/null
+ if [ $? -ne 0 ] ; then
+ echo
+ echo "Diff fails with these switches:"
+ echo $switches
+ echo "Differences:"
+ diff "$dir1/$optll" "$dir2/$optll" | head
+ exit 1
+ fi
+ return 1
+ }
+
+ for sw in $all_switches ; do
+ echo -n " $sw"
+ switches="$switches $sw"
+ if tryit "$switches" ; then
+ break;
+ fi
+ done
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