[llvm-commits] CVS: llvm/utils/findoptdiff

[Reid Spencer]

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