[patch] Dotty printer for dependency trees

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#1

Hi,

I started to work with llvm and liked the CFG dotty printer a lot.
However there was none for the dominance trees.

I implemented dotty printing for dominance trees and introduced these
new flags:

-dot-dom : Print dominance tree of function to 'dot' file
-dot-dom-only : Print dominance tree of function to 'dot' file
                     (with no function bodies)
-dot-postdom : Print postdominance tree of function to 'dot' file
-dot-postdom-only : Print postdominance tree of function to 'dot' file
                     (with no function bodies)

-view-dom : View dominance tree of function
-view-dom-only : View dominance tree of function
                     (with no function bodies)
-view-postdom : View postdominance tree of function
-view-postdom-only : View postdominance tree of function
                     (with no function bodies)

The patch contains these changes:

1. Move DOTGraphTraits<const Function*> to CFGPrinter.h to reuse it
later.

2. Add nodes_iterator to GraphTraits<DomTreeNode *>,
GraphTraits<DominatorTree*>, GraphTraits<PostDominatorTree*> to enable
the GraphWriter on these data structures.

3. The file DomPrinter.cpp containing the actual passes, printers & Co.
It is simple as almost everything already existed.

4. A little bug fix in lib/Analysis/CFGPrinter.cpp.

     virtual bool runOnFunction(Function &F) {
- F.viewCFG();
+ F.viewCFGOnly();
       return false;

"opt -view-cfg-only" showed too much.

Any feedback is highly appreciated.

See you

Tobi

#2

And here is the patch.

Tobi

llvm-dot-dominance-printer.patch (18.8 KB)

#3

Tobias Grosser wrote:

Hi,

I started to work with llvm and liked the CFG dotty printer a lot.
However there was none for the dominance trees.

I implemented dotty printing for dominance trees

Great! I'm a huge fan of graphviz integration in the compiler.

And here is the patch.

What's up with copying from CFGPrinter.cpp into CFGPrinter.h? You shouldn't need that.

+ static nodes_iterator nodes_begin (DomTreeNode * N) {
+ return df_begin<DomTreeNode *> (N);
+ }

#4

Tobias Grosser wrote:
>> Hi,
>>
>> I started to work with llvm and liked the CFG dotty printer a lot.
>> However there was none for the dominance trees.
>>
>> I implemented dotty printing for dominance trees

Great! I'm a huge fan of graphviz integration in the compiler.

> And here is the patch.

What's up with copying from CFGPrinter.cpp into CFGPrinter.h? You
shouldn't need that.

CFGPrinter.cpp implements the printing for a graph of basic blocks, in
this case for an CFG. The nodes in the case of dominance information are
also basic blocks, so I want to use the same code to print these.
As the template is defined in the *.cpp file it can not be accessed,
therefore I moved it to the .h file.

The function I am calling is:

DOTGraphTraits<const Function*>::getNodeLabel(const BasicBlock*, const
Function *, bool);

Is there any way to access the template in the *.cpp file? I do not want
to just copy the code or write my own version of basic block printing.
It would not be different from the current one.

+ static nodes_iterator nodes_begin (DomTreeNode * N) {
+ return df_begin<DomTreeNode *> (N);
+ }
+
+ static nodes_iterator nodes_end (DomTreeNode *N) {
+ return df_end<DomTreeNode *> (N);
+ }

No spaces between the function name and the parenthesis. This occurs a
few times.

Fixed.

@@ -112,7 +59,7 @@ namespace {
      CFGOnlyViewer() : FunctionPass(&ID) {}

      virtual bool runOnFunction(Function &F) {
- F.viewCFG();
+ F.viewCFGOnly();
        return false;
      }

Put that back. viewCFG shows the CFG with full instructions inside it
while viewCFGOnly shows just the block without the instruction listing
inside. This pass is intended to show the details.

I thought the CFGViewer pass triggered on '-view-cfg' should show
details, whereas the CFGOnlyViewer triggered on '-view-cfg-only' should
show the blocks without instructions.
At the moment CFGOnlyViewer as triggered by '-view-cfg-only' shows the
instructions, that seems to be wrong.

+ template<>
+ struct DOTGraphTraits<DomTreeNode*> : public DefaultDOTGraphTraits {
+ static std::string getNodeLabel(DomTreeNode *Node,
+ DomTreeNode *Graph,
+ bool ShortNames) {

Tabs are forbidden in LLVM. Also, neither "namespace llvm {" nor
"template<>" increase indent level.

Fixed.

+ return DOTGraphTraits<const Function*>::getNodeLabel(
+ (const BasicBlock*) BB, (const Function *) BB->getParent(),
+ ShortNames);
+ }

If you're just changing constness, please use const_cast<>. But why
isn't this using DOMGraphTraits<Function*> instead?

I removed them, as they are not required. However I still have to use
the DOTGraphTraits<const Function*> template, as there does not exist
any template for DOTGraphTraits<Function*> and using
DOTGraphTraits<Function*> will not fall back to DOTGraphTraits<const
Function*>, but to the default implementation of DOTGraphTraits. That is
not what I want. As the graph printer does not modify the graph it seems
correct to define everything as 'const', so defining
DOTGraphTraits<Function*> does not seem to be a solution.

+ struct DomViewer: public FunctionPass {

Missing space before colon.

Fixed.

Thanks for your review

Tobias

llvm-dot-dominance-printer.patch (19.4 KB)