Adding upstream version 1:7.0.4.upstream/1%7.0.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 139 insertions, 0 deletions

diff --git a/compilerplugins/clang/pahole-all-classes.py b/compilerplugins/clang/pahole-all-classes.py
new file mode 100755
index 000000000..b95b92543
--- /dev/null
+++ b/compilerplugins/clang/pahole-all-classes.py
@@ -0,0 +1,139 @@
+#!/usr/bin/python3
+#
+# Find holes in structures, so that we can pack them and improve our memory density.
+#
+# In order to make this work, you need to
+# (1) Be operating in a workspace where you have a __NON-DEBUG__ build of LibreOffice, but __WITH SYMBOLS__.
+#     (A debug build has different sizes for some things in the standard library.)
+# (2) First run the unusedfields loplugin to generate a log file
+# (3) Install the pahole stuff into your gdb, I used this one:
+#     https://github.com/PhilArmstrong/pahole-gdb
+# (4) Edit the loop near the top of the script to only produce results for one of our modules.
+#     Note that this will make GDB soak up about 8G of RAM, which is why I don't do more than one module at a time
+# (5) Run the script
+#     ./compilerplugins/clang/pahole-all-classes.py > ./compilerplugins/clang/pahole.results
+#
+
+import _thread
+import io
+import os
+import subprocess
+import time
+import re
+
+# search for all the class names in the file produced by the unusedfields loplugin
+#a = subprocess.Popen("grep 'definition:' workdir/loplugin.unusedfields.log | sort -u", stdout=subprocess.PIPE, shell=True)
+a = subprocess.Popen("cat n1", stdout=subprocess.PIPE, shell=True)
+
+classSet = set()
+classSourceLocDict = dict()
+with a.stdout as txt:
+    for line in txt:
+        tokens = line.decode('utf8').strip().split("\t")
+        className = tokens[2].strip()
+        srcLoc = tokens[5].strip()
+        # ignore things like unions
+        if "anonymous" in className: continue
+        # ignore duplicates
+        if className in classSet: continue
+        classSet.add(className)
+        classSourceLocDict[className] = srcLoc
+a.terminate()
+
+# Some of the pahole commands are going to fail, and I cannot read the error stream and the input stream
+# together because python has no way of (easily) doing a non-blocking read.
+# So I have to write the commands out using a background thread, and then read the entire resulting
+# stream out below.
+def write_pahole_commands(classes):
+    for className in classes:
+        stdin.write("echo " + className + " " + classSourceLocDict[className] + "\n")
+        stdin.write("pahole " + className + "\n")
+        stdin.flush()
+    stdin.write("echo all-done\n")
+    stdin.flush()
+    stdin.close() # only way to make it flush the last echo command
+
+# Use generator because lines often end up merged together in gdb's output, and we need
+# to split them up, and that creates a mess in the parsing logic.
+def read_generator(gdbOutput):
+    while True:
+        line = gdbOutput.readline().decode('utf8').strip()
+        for split in line.split("(gdb)"):
+            split = split.strip()
+            if len(split) == 0: continue
+            if "all-done" in split: return
+            yield split
+
+classList = sorted(classSet)
+
+# Process 200 classes at a time, otherwise gdb's memory usage blows up and kills the machine
+#
+while len(classList) > 0:
+
+    currClassList = classList[1:200];
+    classList = classList[200:]
+
+    gdbProc = subprocess.Popen("gdb", stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True)
+
+    stdin = io.TextIOWrapper(gdbProc.stdin, 'utf-8')
+
+    # make gdb load all the debugging info
+    stdin.write("set confirm off\n")
+    for filename in sorted(os.listdir('instdir/program')):
+        if filename.endswith(".so"):
+            stdin.write("add-symbol-file instdir/program/" + filename + "\n")
+    stdin.flush()
+
+
+    _thread.start_new_thread( write_pahole_commands, (currClassList,) )
+
+    firstLineRegex = re.compile("/\*\s+(\d+)\s+\*/ struct")
+    fieldLineRegex = re.compile("/\*\s+(\d+)\s+(\d+)\s+\*/ ")
+    holeLineRegex = re.compile("/\* XXX (\d+) bit hole, try to pack \*/")
+    # sometimes pahole can't determine the size of a sub-struct, and then it returns bad data
+    bogusLineRegex = re.compile("/\*\s+\d+\s+0\s+\*/")
+    structLines = list()
+    foundHole = False
+    cumulativeHoleBits = 0
+    structSize = 0
+    foundBogusLine = False
+    # pahole doesn't report space at the end of the structure, so work it out myself
+    sizeOfFields = 0
+    for line in read_generator(gdbProc.stdout):
+        structLines.append(line)
+        firstLineMatch = firstLineRegex.match(line)
+        if firstLineMatch:
+            structSize = int(firstLineMatch.group(1))
+        holeLineMatch = holeLineRegex.match(line)
+        if holeLineMatch:
+            foundHole = True
+            cumulativeHoleBits += int(holeLineMatch.group(1))
+        fieldLineMatch = fieldLineRegex.match(line)
+        if fieldLineMatch:
+            fieldSize = int(fieldLineMatch.group(2))
+            sizeOfFields = int(fieldLineMatch.group(1)) + fieldSize
+        if bogusLineRegex.match(line):
+            foundBogusLine = True
+        if line == "}":
+            # Ignore very large structs, packing those is not going to help much, and
+            # re-organising them can make them much less readable.
+            if foundHole and len(structLines) < 12 and structSize < 100 and not foundBogusLine:
+                # Verify that we have enough hole-space that removing it will result in a structure
+                # that still satisfies alignment requirements, otherwise the compiler will just put empty
+                # space at the end of the struct.
+                # TODO improve detection of the required alignment for a structure
+                potentialSpace = (cumulativeHoleBits / 8) + (sizeOfFields - structSize)
+                if potentialSpace >= 8:
+                    for line in structLines:
+                        print(line)
+                    if (sizeOfFields - structSize) > 0:
+                        print("hole at end of struct: " + str(sizeOfFields - structSize))
+            #  reset state
+            structLines.clear()
+            foundHole = False
+            cumulativeHoleBits = 0
+            structSize = 0
+            foundBogusLine = False
+            actualStructSize = 0
+
+    gdbProc.terminate()