[CFGPrinter] Allow CFG dumps with a given filename

[LewisCrawford]

Add functions to print the CFG via the debugger using a specified filename.

This is useful when comparing CFGs for the same function before vs after a change, or when handling functions with names that are too long to be file names.

[llvmbot]

@llvm/pr-subscribers-llvm-ir

@llvm/pr-subscribers-llvm-analysis

Author: Lewis Crawford (LewisCrawford)

Changes

Add functions to print the CFG via the debugger using a specified filename.

This is useful when comparing CFGs for the same function before vs after a change, or when handling functions with names that are too long to be file names.

---

Full diff: https://github.com/llvm/llvm-project/pull/112906.diff

2 Files Affected:

• (modified) llvm/include/llvm/IR/Function.h (+10-1)
• (modified) llvm/lib/Analysis/CFGPrinter.cpp (+11-2)

diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 43bf36d6f1eec9..abe574a077f24a 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -942,9 +942,14 @@ class LLVM_ABI Function : public GlobalObject, public ilist_node<Function> {
   ///
   void viewCFG() const;
 
+  /// viewCFG - This function is meant for use from the debugger. It works just
+  /// like viewCFG(), but generates the dot file with the given filename.
+  void viewCFG(const char *Name) const;
+
   /// Extended form to print edge weights.
   void viewCFG(bool ViewCFGOnly, const BlockFrequencyInfo *BFI,
-               const BranchProbabilityInfo *BPI) const;
+               const BranchProbabilityInfo *BPI,
+               const char *Name = nullptr) const;
 
   /// viewCFGOnly - This function is meant for use from the debugger.  It works
   /// just like viewCFG, but it does not include the contents of basic blocks
@@ -953,6 +958,10 @@ class LLVM_ABI Function : public GlobalObject, public ilist_node<Function> {
   ///
   void viewCFGOnly() const;
 
+  /// viewCFG - This function is meant for use from the debugger. It works just
+  /// like viewCFGOnly(), but generates the dot file with the given filename.
+  void viewCFGOnly(const char *Name) const;
+
   /// Extended form to print edge weights.
   void viewCFGOnly(const BlockFrequencyInfo *BFI,
                    const BranchProbabilityInfo *BPI) const;
diff --git a/llvm/lib/Analysis/CFGPrinter.cpp b/llvm/lib/Analysis/CFGPrinter.cpp
index 67a15197058b73..dc07d8239bd889 100644
--- a/llvm/lib/Analysis/CFGPrinter.cpp
+++ b/llvm/lib/Analysis/CFGPrinter.cpp
@@ -136,12 +136,17 @@ PreservedAnalyses CFGOnlyPrinterPass::run(Function &F,
 ///
 void Function::viewCFG() const { viewCFG(false, nullptr, nullptr); }
 
+void Function::viewCFG(const char *Name) const {
+  viewCFG(false, nullptr, nullptr, Name);
+}
+
 void Function::viewCFG(bool ViewCFGOnly, const BlockFrequencyInfo *BFI,
-                       const BranchProbabilityInfo *BPI) const {
+                       const BranchProbabilityInfo *BPI,
+                       const char *Name) const {
   if (!CFGFuncName.empty() && !getName().contains(CFGFuncName))
     return;
   DOTFuncInfo CFGInfo(this, BFI, BPI, BFI ? getMaxFreq(*this, BFI) : 0);
-  ViewGraph(&CFGInfo, "cfg" + getName(), ViewCFGOnly);
+  ViewGraph(&CFGInfo, Name ? Name : "cfg" + getName(), ViewCFGOnly);
 }
 
 /// viewCFGOnly - This function is meant for use from the debugger.  It works
@@ -151,6 +156,10 @@ void Function::viewCFG(bool ViewCFGOnly, const BlockFrequencyInfo *BFI,
 ///
 void Function::viewCFGOnly() const { viewCFGOnly(nullptr, nullptr); }
 
+void Function::viewCFGOnly(const char *Name) const {
+  viewCFG(true, nullptr, nullptr, Name);
+}
+
 void Function::viewCFGOnly(const BlockFrequencyInfo *BFI,
                            const BranchProbabilityInfo *BPI) const {
   viewCFG(true, BFI, BPI);

[LewisCrawford]

Requesting review from @WenleiHe and @david-xl , as they reviewed a similar CFGPrinter debugger utils patch a few years ago in https://reviews.llvm.org/D77978

[WenleiHe]

lgtm with a nit. thanks.