Add a utility script for displaying the CFG of SIL or LLVM IR.

It is useful if you have the SIL already in a file (instead of calling viewCFG() while running the compiler in lldb).

Especially useful for vim users: see the comment in the script on how to add commands to view the CFG from inside vim.




Swift SVN r30186

Author: eeckstein

docs/DebuggingTheCompiler.rst

@@ -113,6 +113,15 @@ debugging press <CTRL>-C on the LLDB prompt.
 Note that this only works in Xcode if the PATH variable in the scheme's
 environment setting contains the path to the dot tool.
 
+Other Utilities
+```````````````
+
+To view the CFG of a function (or code region) in a SIL file, you can use the
+script ``swift/utils/viewcfg``. It also works for LLVM IR files.
+The script reads the SIL (or LLVM IR) code from stdin and displays the dot
+graph file. Note: .dot files should be associated with the Graphviz app.
+
+
 Using Breakpoints
 `````````````````
 

utils/viewcfg

@@ -0,0 +1,166 @@
+#!/usr/bin/env python
+
+# A script for viewing the CFG of SIL and llvm IR.
+
+# For vim users: use the following lines in .vimrc
+#
+#   com! -nargs=? Funccfg silent ?{$?,/^}/w !viewcfg <args>
+#   com! -range -nargs=? Viewcfg silent <line1>,<line2>w !viewcfg <args>
+#
+# to add these commands:
+#
+#   :Funccfg        displays the CFG of the current SIL/llvm function.
+#   :<range>Viewcfg displays the sub-CFG of the selected range.
+#
+# Note: viewcfg should be in the $PATH and .dot files should be associated
+# with the Graphviz app.
+
+import re
+import sys
+import tempfile
+import subprocess
+import os
+
+def help():
+  print """\
+Usage:
+
+viewcfg [output-suffix] < file
+
+By default all CFGs are opened in the same window.
+Use the a unique output-suffix to open a CFG in a new window.
+"""
+
+class Block:
+
+    currentIndex = 0
+
+    def __init__(self, name, preds):
+        self.name = name
+        self.content = None
+        self.lastLineContent = None
+        self.preds = []
+        self.succs = None
+        self.lastLine = None
+        self.index = Block.currentIndex
+        Block.currentIndex +=  1
+        if preds is not None:
+            for pred in re.split("[, %]", preds):
+                canPred = pred.strip()
+                if canPred:
+                    self.preds.append(canPred)
+
+    def addLine(self, text):
+        if self.content is None:
+            self.content = ""
+        escapedText = re.sub(r'([\\<>{}"|])', r'\\\1', text[0:80]).rstrip()
+        self.content += escapedText + '\\l'
+        self.lastLine = text
+
+    def getSuccs(self):
+        if self.succs is None:
+            self.succs = []
+            if self.lastLine is not None:
+                for match in re.finditer(r'\bbb[0-9]+\b', self.lastLine):
+                    self.succs.append(match.group())
+
+                for match in re.finditer(r'\blabel %(\S+)\b', self.lastLine):
+                    self.succs.append(match.group(1))
+
+        return self.succs
+
+def main():
+    suffix = ""
+    if len(sys.argv) >= 2:
+        if sys.argv[1].startswith('-'):
+            help()
+            return
+        suffix = sys.argv[1]
+
+    blocks = { }
+    curBlock = None
+    silBlockPattern = re.compile(r'^(\S+)(\(.*\))?: *(\/\/ *Preds:(.*))?$')
+    llvmBlockPattern1 = re.compile(r'^(\S+): *; *preds =(.*)?$')
+    llvmBlockPattern2 = re.compile(r'^; <label>:(\d+) *; *preds =(.*)?$')
+
+    # Scan the input file.
+
+    for line in sys.stdin:
+        silBlockMatch = silBlockPattern.match(line)
+        llvmBlockMatch1 = llvmBlockPattern1.match(line)
+        llvmBlockMatch2 = llvmBlockPattern2.match(line)
+        blockName = None
+        preds = None
+        if silBlockMatch:
+            blockName = silBlockMatch.group(1)
+            preds = silBlockMatch.group(4)
+        elif llvmBlockMatch1:
+            blockName = llvmBlockMatch1.group(1)
+            preds = llvmBlockMatch1.group(2)
+        elif llvmBlockMatch2:
+            blockName = llvmBlockMatch2.group(1)
+            preds = llvmBlockMatch2.group(2)
+        elif line.startswith(' '):
+            if curBlock is not None:
+                curBlock.addLine(line)
+        elif not line[:1].isspace():
+            if line.startswith('}') and blocks:
+                break
+            curBlock = None
+
+        if blockName is not None:
+            curBlock = Block(blockName, preds)
+            curBlock.addLine(line)
+            blocks[blockName] = curBlock
+
+
+    # Add empty blocks which we didn't see, but which are referenced.
+
+    newBlocks = { }
+    for name, block in blocks.iteritems():
+        for adjName in (block.preds + block.getSuccs()):
+            if not adjName in blocks:
+                newBlocks[adjName] = Block(adjName, None)
+
+    blocks = dict(blocks.items() + newBlocks.items())
+
+    # Add missing edges if we didn't see a successor in the terminator
+    # but the block is mentioned in the pred list of the successor.
+
+    for name, block in blocks.iteritems():
+        for predName in block.preds:
+            predBlock = blocks[predName]
+            if not name in predBlock.getSuccs():
+                predBlock.getSuccs().append(name)
+
+    # Write the output dot file.
+
+    fileName = tempfile.gettempdir() + "/viewcfg" + suffix + ".dot"
+    outFile = open(fileName, "w")
+
+    outFile.write('digraph "CFG" {\n')
+    for name, block in blocks.iteritems():
+        if block.content is not None:
+            outFile.write("\tNode" + str(block.index) + \
+                " [shape=record,label=\"{" + block.content + "}\"];\n")
+        else:
+            outFile.write("\tNode" + str(block.index) + \
+                " [shape=record,color=gray,fontcolor=gray,label=\"{" + \
+                block.name + "}\"];\n")
+
+        for succName in block.getSuccs():
+            succBlock = blocks[succName]
+            outFile.write("\tNode" + str(block.index) + " -> Node" + \
+                str(succBlock.index) + ";\n")
+
+    outFile.write("}\n")
+    outFile.flush()
+    os.fsync(outFile.fileno())
+    outFile.close
+
+    # Open the dot file (should be done with Graphviz).
+
+    subprocess.call(["open", fileName])
+
+main()
+