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, 9 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index ec6062a..a9a2db1 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -987,6 +987,9 @@ static bool addNoRecurseAttrs(const SCCNodeSet &SCCNodes) {
 
 PreservedAnalyses PostOrderFunctionAttrsPass::run(LazyCallGraph::SCC &C,
                                                   CGSCCAnalysisManager &AM) {
+  if (skipPassForSCC(name(), C))
+    return PreservedAnalyses::all();
+
   Module &M = *C.begin()->getFunction().getParent();
   const ModuleAnalysisManager &MAM =
       AM.getResult<ModuleAnalysisManagerCGSCCProxy>(C).getManager();
@@ -1081,6 +1084,9 @@ INITIALIZE_PASS_END(PostOrderFunctionAttrsLegacyPass, "functionattrs",
 Pass *llvm::createPostOrderFunctionAttrsLegacyPass() { return new PostOrderFunctionAttrsLegacyPass(); }
 
 bool PostOrderFunctionAttrsLegacyPass::runOnSCC(CallGraphSCC &SCC) {
+  if (skipSCC(SCC))
+    return false;
+
   TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
   bool Changed = false;
 
@@ -1195,6 +1201,9 @@ static bool addNoRecurseAttrsTopDown(Function &F) {
 }
 
 bool ReversePostOrderFunctionAttrs::runOnModule(Module &M) {
+  if (skipModule(M))
+    return false;
+
   // We only have a post-order SCC traversal (because SCCs are inherently
   // discovered in post-order), so we accumulate them in a vector and then walk
   // it in reverse. This is simpler than using the RPO iterator infrastructure