[mc] Add stack-cleaning compiler wrappers

This compiler wrappers clear each satck frame before using it in order
to avoid issues with unitialized variables in SimGridMC state
comparison.

Compiling with those compiler is much slower.

diff --git a/tools/stack-cleaner/README b/tools/stack-cleaner/README
new file mode 100644 (file)
index 0000000..0aa98f8
--- /dev/null
+++ b/tools/stack-cleaner/README
@@ -0,0 +1,21 @@
+Provides stack-cleaning compilers for x86_64:
+
+ * as
+ * cc
+ * c++
+
+Each of them modify the generated/given X86_64 assembly by prepending
+stack-cleanup code to each function:
+
+       movq $QSIZE, %r11
+.Lloop:
+        movq $0, OFFSET(%rsp,%r11,8)
+        subq $1, %r11
+        jne  .Lloop
+
+The modification of the assembly is done by the clean-stack-filter
+program.
+
+If the underlying compiler is clang, it might be necessary to add the
+-no-integrated-as flag in order to force the usage of an external
+assembler.

diff --git a/tools/stack-cleaner/as b/tools/stack-cleaner/as
new file mode 100755 (executable)
index 0000000..dcdb491
--- /dev/null
+++ b/tools/stack-cleaner/as
@@ -0,0 +1,57 @@
+#!/usr/bin/ruby
+# Wrapper around the real `as` which adds filtering capabilities.
+
+require "tempfile"
+require "fileutils"
+
+def wrapped_as(argv)
+
+  args=[]
+  input=nil
+
+  i = 0
+  while i<argv.size
+    case argv[i]
+    when "-o", "-I"
+      args.push(argv[i])
+      args.push(argv[i+1])
+      i = i + 1
+    when /^-/
+      args.push(argv[i])
+    else
+      if input
+        exit 1
+      else
+        input = argv[i]
+      end
+    end
+    i = i + 1
+  end
+
+  if input==nil
+    # We dont handle pipe yet:
+    exit 1
+  end
+
+  # Generate temp file
+  tempfile = Tempfile.new("as-filter")
+  unless system(File.dirname($0) + "/clean-stack-filter", 0 => input, 1 => tempfile)
+    status=$?.exitstatus
+    FileUtils.rm tempfile
+    exit status
+  end
+  args.push(tempfile.path)
+
+  # Call the real assembler:
+  res = system("as", *args)
+  status = if res != nil
+             $?.exitstatus
+           else
+             1
+           end
+  FileUtils.rm tempfile
+  exit status
+
+end
+
+wrapped_as(ARGV)

diff --git a/tools/stack-cleaner/c++ b/tools/stack-cleaner/c++
new file mode 100755 (executable)
index 0000000..516d36c
--- /dev/null
+++ b/tools/stack-cleaner/c++
@@ -0,0 +1,3 @@
+#!/bin/sh
+path="$(dirname $0)"
+exec "${FILTER_CXX:-c++}" -B "$path" "$@"

diff --git a/tools/stack-cleaner/cc b/tools/stack-cleaner/cc
new file mode 100755 (executable)
index 0000000..3cfd378
--- /dev/null
+++ b/tools/stack-cleaner/cc
@@ -0,0 +1,3 @@
+#!/bin/sh
+path="$(dirname $0)"
+exec "${FILTER_CC:-cc}" -B "$path" "$@"

diff --git a/tools/stack-cleaner/clean-stack-filter b/tools/stack-cleaner/clean-stack-filter
new file mode 100755 (executable)
index 0000000..8c5c01c
--- /dev/null
+++ b/tools/stack-cleaner/clean-stack-filter
@@ -0,0 +1,61 @@
+#!/usr/bin/perl -w
+# Transform assembly in order to clean each stack frame for X86_64.
+
+use strict;
+$SIG{__WARN__} = sub { die @_ };
+
+
+# Whether we are still scanning the content of a function:
+our $scanproc = 0;
+
+# Save lines of the function:
+our $lines = "";
+
+# Size of the stack for this function:
+our $size = 0;
+
+
+# Counter for assigning unique ids to labels:
+our $id=0;
+
+sub emit_code {
+    my $qsize = $size / 8;
+    my $offset = - $size - 8;
+
+    if($size != 0) {
+      print("\tmovabsq \$$qsize, %r11\n");
+      print(".Lstack_cleaner_loop$id:\n");
+      print("\tmovq    \$0, $offset(%rsp,%r11,8)\n");
+      print("\tsubq    \$1, %r11\n");
+      print("\tjne     .Lstack_cleaner_loop$id\n");
+    }
+
+    print $lines;
+
+    $id = $id + 1;
+    $size = 0;
+    $lines = "";
+    $scanproc = 0;
+}
+
+while (<>) {
+  if ($scanproc) {
+      $lines = $lines . $_;
+      if (m/^[ \t]*.cfi_endproc$/) {
+         emit_code();
+      } elsif (m/^[ \t]*pushq/) {
+         $size += 8;
+      } elsif (m/^[ \t]*subq[\t *]\$([0-9]*),[ \t]*%rsp$/) {
+          my $val = $1;
+          $val = oct($val) if $val =~ /^0/;
+          $size += $val;
+          emit_code();
+      }
+  } elsif (m/^[ \t]*.cfi_startproc$/) {
+      print $_;
+
+      $scanproc = 1;
+  } else {
+      print $_;
+  }
+}