Add an option to turn off the expensive GVN load PRE part of GVN.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153902 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 13 insertions, 6 deletions

diff --git a/include/llvm/Transforms/IPO/PassManagerBuilder.h b/include/llvm/Transforms/IPO/PassManagerBuilder.h
index 734f37e52e..47ce90265b 100644
--- a/include/llvm/Transforms/IPO/PassManagerBuilder.h
+++ b/include/llvm/Transforms/IPO/PassManagerBuilder.h
@@ -131,8 +131,9 @@ public:
   /// populateModulePassManager - This sets up the primary pass manager.
   void populateModulePassManager(PassManagerBase &MPM);
   void populateLTOPassManager(PassManagerBase &PM, bool Internalize,
-                              bool RunInliner);
+                              bool RunInliner, bool DisableGVNLoadPRE = false);
 };
+
 /// Registers a function for adding a standard set of passes.  This should be
 /// used by optimizer plugins to allow all front ends to transparently use
 /// them.  Create a static instance of this class in your plugin, providing a
@@ -143,5 +144,6 @@ struct RegisterStandardPasses {
     PassManagerBuilder::addGlobalExtension(Ty, Fn);
   }
 };
+
 } // end namespace llvm
 #endif
diff --git a/lib/Transforms/IPO/PassManagerBuilder.cpp b/lib/Transforms/IPO/PassManagerBuilder.cpp
index 243ba1a85b..a1b0a4580b 100644
--- a/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -207,7 +207,8 @@ void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
 
 void PassManagerBuilder::populateLTOPassManager(PassManagerBase &PM,
                                                 bool Internalize,
-                                                bool RunInliner) {
+                                                bool RunInliner,
+                                                bool DisableGVNLoadPRE) {
   // Provide AliasAnalysis services for optimizations.
   addInitialAliasAnalysisPasses(PM);
 
@@ -263,9 +264,9 @@ void PassManagerBuilder::populateLTOPassManager(PassManagerBase &PM,
   PM.add(createFunctionAttrsPass()); // Add nocapture.
   PM.add(createGlobalsModRefPass()); // IP alias analysis.
 
-  PM.add(createLICMPass());      // Hoist loop invariants.
-  PM.add(createGVNPass());       // Remove redundancies.
-  PM.add(createMemCpyOptPass()); // Remove dead memcpys.
+  PM.add(createLICMPass());                 // Hoist loop invariants.
+  PM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
+  PM.add(createMemCpyOptPass());            // Remove dead memcpys.
   // Nuke dead stores.
   PM.add(createDeadStoreEliminationPass());
 
diff --git a/tools/lto/LTOCodeGenerator.cpp b/tools/lto/LTOCodeGenerator.cpp
index 1d2631e07d..f0640c2206 100644
--- a/tools/lto/LTOCodeGenerator.cpp
+++ b/tools/lto/LTOCodeGenerator.cpp
@@ -49,6 +49,9 @@ using namespace llvm;
 static cl::opt<bool> DisableInline("disable-inlining",
   cl::desc("Do not run the inliner pass"));
 
+static cl::opt<bool> DisableGVNLoadPRE("disable-gvn-loadpre",
+  cl::desc("Do not run the GVN load PRE pass"));
+
 const char* LTOCodeGenerator::getVersionString() {
 #ifdef LLVM_VERSION_INFO
   return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
@@ -353,7 +356,8 @@ bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
   passes.add(new TargetData(*_target->getTargetData()));
 
   PassManagerBuilder().populateLTOPassManager(passes, /*Internalize=*/ false,
-                                              !DisableInline);
+                                              !DisableInline,
+                                              DisableGVNLoadPRE);
 
   // Make sure everything is still good.
   passes.add(createVerifierPass());