Initial implementation of optimization bisect support.

This patch implements a optimization bisect feature, which will allow optimizations to be selectively disabled at compile time in order to track down test failures that are caused by incorrect optimizations.

The bisection is enabled using a new command line option (-opt-bisect-limit).  Individual passes that may be skipped call the OptBisect object (via an LLVMContext) to see if they should be skipped based on the bisect limit.  A finer level of control (disabling individual transformations) can be managed through an addition OptBisect method, but this is not yet used.

The skip checking in this implementation is based on (and replaces) the skipOptnoneFunction check.  Where that check was being called, a new call has been inserted in its place which checks the bisect limit and the optnone attribute.  A new function call has been added for module and SCC passes that behaves in a similar way.

Differential Revision: http://reviews.llvm.org/D19172

llvm-svn: 267022

1 files changed, 8 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/CallGraphSCCPass.cpp b/llvm/lib/Analysis/CallGraphSCCPass.cpp
index 6dd1d0a066b..71226bd25ca 100644
--- a/llvm/lib/Analysis/CallGraphSCCPass.cpp
+++ b/llvm/lib/Analysis/CallGraphSCCPass.cpp
@@ -23,6 +23,7 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/LegacyPassManagers.h"
+#include "llvm/IR/OptBisect.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Timer.h"
@@ -444,7 +445,7 @@ bool CGPassManager::runOnModule(Module &M) {
   // Walk the callgraph in bottom-up SCC order.
   scc_iterator<CallGraph*> CGI = scc_begin(&CG);
 
-  CallGraphSCC CurSCC(&CGI);
+  CallGraphSCC CurSCC(CG, &CGI);
   while (!CGI.isAtEnd()) {
     // Copy the current SCC and increment past it so that the pass can hack
     // on the SCC if it wants to without invalidating our iterator.
@@ -631,3 +632,9 @@ Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
   return new PrintCallGraphPass(Banner, O);
 }
 
+bool CallGraphSCCPass::skipSCC(CallGraphSCC &SCC) const {
+  return !SCC.getCallGraph().getModule()
+              .getContext()
+              .getOptBisect()
+              .shouldRunPass(this, SCC);
+}