Add some switches helpful for debugging:

-print-before=<Pass Name>

Dump IR before running pass <Pass Name>.

-print-before-all

Dump IR before running each pass.

-print-after-all

Dump IR after running each pass.

These are helpful when tracking down a miscompilation.  It is easy to
get IR dumps and do diffs on them, etc.

To make this work well, add a new getPrinterPass API to Pass so that
each kind of pass (ModulePass, FunctionPass, etc.) can create a Pass
suitable for dumping out the kind of object the Pass works on.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100143 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/VMCore/Pass.cpp b/lib/VMCore/Pass.cpp
index a782e5a82e..6093750124 100644
--- a/lib/VMCore/Pass.cpp
+++ b/lib/VMCore/Pass.cpp
@@ -18,6 +18,7 @@
 #include "llvm/Module.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Assembly/PrintModulePass.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/PassNameParser.h"
@@ -42,6 +43,11 @@ Pass::~Pass() {
 // Force out-of-line virtual method.
 ModulePass::~ModulePass() { }
 
+Pass *ModulePass::createPrinterPass(raw_ostream &O,
+                                    const std::string &Banner) const {
+  return createPrintModulePass(&O, false, Banner);
+}
+
 PassManagerType ModulePass::getPotentialPassManagerType() const {
   return PMT_ModulePassManager;
 }
@@ -113,6 +119,11 @@ void ImmutablePass::initializePass() {
 // FunctionPass Implementation
 //
 
+Pass *FunctionPass::createPrinterPass(raw_ostream &O,
+                                      const std::string &Banner) const {
+  return createPrintFunctionPass(Banner, &O);
+}
+
 // run - On a module, we run this pass by initializing, runOnFunction'ing once
 // for every function in the module, then by finalizing.
 //
@@ -155,6 +166,13 @@ PassManagerType FunctionPass::getPotentialPassManagerType() const {
 // BasicBlockPass Implementation
 //
 
+Pass *BasicBlockPass::createPrinterPass(raw_ostream &O,
+                                        const std::string &Banner) const {
+  
+  llvm_unreachable("BasicBlockPass printing unsupported.");
+  return 0;
+}
+
 // To run this pass on a function, we simply call runOnBasicBlock once for each
 // function.
 //