Add flag to PassManagerBuilder to disable GVN Hoist Pass.

Summary:
Adding a flag to diable GVN Hoisting by default.
Note: The GVN Hoist Pass causes some Halide tests to hang. Halide will disable the pass while investigating.

Reviewers: llvm-commits, chandlerc, spop, dberlin

Subscribers: mehdi_amini

Differential Revision: https://reviews.llvm.org/D22639

llvm-svn: 276479

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -134,6 +134,10 @@ static cl::opt<int> PreInlineThreshold(
     cl::desc("Control the amount of inlining in pre-instrumentation inliner "
              "(default = 75)"));
 
+static cl::opt<bool> EnableGVNHoist(
+    "enable-gvn-hoist", cl::init(false), cl::Hidden,
+    cl::desc("Enable the experimental GVN Hoisting pass"));
+
 PassManagerBuilder::PassManagerBuilder() {
     OptLevel = 2;
     SizeLevel = 0;
@@ -232,7 +236,8 @@ void PassManagerBuilder::populateFunctionPassManager(
   FPM.add(createCFGSimplificationPass());
   FPM.add(createSROAPass());
   FPM.add(createEarlyCSEPass());
-  FPM.add(createGVNHoistPass());
+  if(EnableGVNHoist)
+    FPM.add(createGVNHoistPass());
   FPM.add(createLowerExpectIntrinsicPass());
 }
 

llvm/test/Feature/optnone-opt.ll

@@ -41,7 +41,6 @@ attributes #0 = { optnone noinline }
 ; OPT-O1-DAG: Skipping pass 'Combine redundant instructions'
 ; OPT-O1-DAG: Skipping pass 'Dead Store Elimination'
 ; OPT-O1-DAG: Skipping pass 'Early CSE'
-; OPT-O1-DAG: Skipping pass 'Early GVN Hoisting of Expressions'
 ; OPT-O1-DAG: Skipping pass 'Jump Threading'
 ; OPT-O1-DAG: Skipping pass 'MemCpy Optimization'
 ; OPT-O1-DAG: Skipping pass 'Reassociate expressions'