[llvm-bugs] [Bug 120977] scan-build division by zero while calculating the stats

[LLVM Bugs via llvm-bugs]

Issue	120977
Summary	scan-build division by zero while calculating the stats
Labels	new issue
Assignees
Reporter	BebeSparkelSparkel

    ```txt
scan-build: Analysis run complete.
Illegal division by zero at /home/wjr/llvm-project/build/bin/scan-build line 500.
```

Line 500

```perl
  my $PercentAborted = sprintf("%.2f", $Aborted / $TotalFunctions * 100);
```

in the function `CalcStats`

```perl
sub CalcStats {
  my $Stats = shift;

  my $TotalBlocks = 0;
  my $UnreachedBlocks = 0;
  my $TotalFunctions = scalar(@$Stats);
  my $BlockAborted = 0;
  my $WorkListAborted = 0;
  my $Aborted = 0;

  # Calculate the unique files
  my $FilesHash = {};

  foreach my $Row (@$Stats) {
    $FilesHash->{$Row->{Filename}} = 1;
    $TotalBlocks += $Row->{Total};
    $UnreachedBlocks += $Row->{Unreachable};
 $BlockAborted++ if $Row->{Aborted} eq 'yes';
    $WorkListAborted++ if $Row->{Empty} eq 'no';
    $Aborted++ if $Row->{Aborted} eq 'yes' || $Row->{Empty} eq 'no';
  }

  my $TotalFiles = scalar(keys(%$FilesHash));

  # Calculations
  my $PercentAborted = sprintf("%.2f", $Aborted / $TotalFunctions * 100);
  my $PercentBlockAborted = sprintf("%.2f", $BlockAborted / $TotalFunctions
 * 100);
  my $PercentWorkListAborted = sprintf("%.2f", $WorkListAborted /
      $TotalFunctions * 100);
  my $PercentBlocksUnreached = sprintf("%.2f", $UnreachedBlocks / $TotalBlocks
      * 100);

  my $StatsString = "Analyzed $TotalBlocks blocks in $TotalFunctions functions"
    . " in $TotalFiles files\n"
    . "$Aborted functions aborted early ($PercentAborted%)\n"
    . "$BlockAborted had aborted blocks ($PercentBlockAborted%)\n"
    . "$WorkListAborted had unfinished worklists ($PercentWorkListAborted%)\n"
    . "$UnreachedBlocks blocks were never reached ($PercentBlocksUnreached%)\n";

  return $StatsString;
}
```

The command was:

```sh
#!/bin/sh

# Create a clean output directory
REPORT_DIR="/tmp/iked-analysis"
mkdir -p "$REPORT_DIR"

~/llvm-project/build/bin/scan-build \
  --status-bugs \
  --use-cc=clang \
  -analyze-headers \
  -constraints range \
 -enable-checker alpha.core.PointerArithmetic \
  -enable-checker alpha.core.PointerSub \
  -enable-checker alpha.security.ArrayBound \
 -enable-checker alpha.unix.Stream \
  -enable-checker core.CallAndMessage \
  -enable-checker core.DivideZero \
  -enable-checker core.NullDereference \
  -enable-checker core.uninitialized.ArraySubscript \
  -enable-checker core.uninitialized.Assign \
  -enable-checker core.uninitialized.Branch \
  -enable-checker deadcode.DeadStores \
 -enable-checker security \
  -enable-checker unix.API \
  -enable-checker unix.Malloc \
  -enable-checker unix.cstring.BadSizeArg \
 -enable-checker unix.cstring.NullArg \
  -maxloop 30 \
  -o "$REPORT_DIR" \
  -stats \
  -v \
  make \
  CFLAGS="-Wall -I. -Wstrict-prototypes -Wmissing-prototypes \
  -Wmissing-declarations -Wshadow -Wpointer-arith -Wcast-qual \
  -Wsign-compare -DDEBUG"
```

in the OpenBSD iked src directory.

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