GBE: Add a new pass to handle barrier function's noduplicate attribute correctly.

This pass is to remove or add noduplicate function attribute for barrier functions.
Basically, we want to set NoDuplicate for those __gen_barrier_xxx functions. But if
a sub function calls those barrier functions, the sub function will not be inlined
in llvm's inlining pass. This is what we don't want. As inlining such a function in
the caller is safe, we just don't want it to duplicate the call. So Introduce this
pass to remove the NoDuplicate function attribute before the inlining pass and restore
it after.

v2:
fix the module changed check.

Signed-off-by: Zhigang Gong <zhigang.gong@intel.com>
Reviewed-by: "Yang, Rong R" <rong.r.yang@intel.com>
Reviewed-by: "Song, Ruiling" <ruiling.song@intel.com>

5 files changed, 125 insertions, 3 deletions

diff --git a/backend/src/CMakeLists.txt b/backend/src/CMakeLists.txt
index 6e37d95d..d6f2d3c6 100644
--- a/backend/src/CMakeLists.txt
+++ b/backend/src/CMakeLists.txt
@@ -144,6 +144,7 @@ else (GBE_USE_BLOB)
     llvm/llvm_passes.cpp
     llvm/llvm_scalarize.cpp
     llvm/llvm_intrinsic_lowering.cpp
+    llvm/llvm_barrier_nodup.cpp
     llvm/llvm_to_gen.cpp
     llvm/llvm_gen_backend.hpp
     llvm/llvm_gen_ocl_function.hxx
diff --git a/backend/src/llvm/llvm_barrier_nodup.cpp b/backend/src/llvm/llvm_barrier_nodup.cpp
new file mode 100644
index 00000000..cc1e22ce
--- /dev/null
+++ b/backend/src/llvm/llvm_barrier_nodup.cpp
@@ -0,0 +1,117 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * \file llvm_barrier_nodup.cpp
+ *
+ *  This pass is to remove or add noduplicate function attribute for barrier functions.
+ *  Basically, we want to set NoDuplicate for those __gen_barrier_xxx functions. But if
+ *  a sub function calls those barrier functions, the sub function will not be inlined
+ *  in llvm's inlining pass. This is what we don't want. As inlining such a function in
+ *  the caller is safe, we just don't want it to duplicate the call. So Introduce this
+ *  pass to remove the NoDuplicate function attribute before the inlining pass and restore
+ *  it after.
+ *  
+ */
+
+#include "llvm/Config/config.h"
+#if LLVM_VERSION_MINOR <= 2
+#include "llvm/Function.h"
+#include "llvm/InstrTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Module.h"
+#else
+#include "llvm/IR/Function.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#endif  /* LLVM_VERSION_MINOR <= 2 */
+#include "llvm/Pass.h"
+#if LLVM_VERSION_MINOR <= 1
+#include "llvm/Support/IRBuilder.h"
+#elif LLVM_VERSION_MINOR == 2
+#include "llvm/IRBuilder.h"
+#else
+#include "llvm/IR/IRBuilder.h"
+#endif /* LLVM_VERSION_MINOR <= 1 */
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/IR/Attributes.h"
+
+#include "llvm/llvm_gen_backend.hpp"
+#include "sys/map.hpp"
+
+
+using namespace llvm;
+
+namespace gbe {
+    class BarrierNodup : public ModulePass
+    {
+    public:
+      static char ID;
+      BarrierNodup(bool nodup) :
+        ModulePass(ID), nodup(nodup) {}
+
+      void getAnalysisUsage(AnalysisUsage &AU) const {
+
+      }
+
+      virtual const char *getPassName() const {
+        return "SPIR backend: set barrier no duplicate attr";
+      }
+
+      virtual bool runOnModule(Module &M)
+      {
+        using namespace llvm;
+        bool changed = false;
+        for (auto &F : M) {
+          if (F.getName() == "__gen_ocl_barrier_local_and_global" ||
+              F.getName() == "__gen_ocl_barrier_local"            ||
+              F.getName() == "__gen_ocl_barrier_global") {
+            if (nodup) {
+              if (!F.hasFnAttribute(Attribute::NoDuplicate)) {
+                F.addFnAttr(Attribute::NoDuplicate);
+                changed = true;
+              }
+            } else {
+              if (F.hasFnAttribute(Attribute::NoDuplicate)) {
+                auto attrs = F.getAttributes();
+                F.setAttributes(attrs.removeAttribute(M.getContext(),
+                                AttributeSet::FunctionIndex,
+                                Attribute::NoDuplicate));
+                changed = true;
+              }
+            }
+          }
+        }
+
+        return changed;
+      }
+    private:
+      bool nodup;
+    };
+
+
+    ModulePass *createBarrierNodupPass(bool Nodup) {
+      return new BarrierNodup(Nodup);
+    }
+
+    char BarrierNodup::ID = 0;
+} // end namespace
diff --git a/backend/src/llvm/llvm_gen_backend.hpp b/backend/src/llvm/llvm_gen_backend.hpp
index 389d5f36..56dd27f3 100644
--- a/backend/src/llvm/llvm_gen_backend.hpp
+++ b/backend/src/llvm/llvm_gen_backend.hpp
@@ -86,6 +86,8 @@ namespace gbe
 
   /*! Scalarize all vector op instructions */
   llvm::FunctionPass* createScalarizePass();
+  /*! Remove/add NoDuplicate function attribute for barrier functions. */
+  llvm::ModulePass* createBarrierNodupPass(bool);
 
   /*! Convert the Intrinsic call to gen function */
   llvm::BasicBlockPass *createIntrinsicLoweringPass();
diff --git a/backend/src/llvm/llvm_to_gen.cpp b/backend/src/llvm/llvm_to_gen.cpp
index 9e18a578..4d064a24 100644
--- a/backend/src/llvm/llvm_to_gen.cpp
+++ b/backend/src/llvm/llvm_to_gen.cpp
@@ -112,7 +112,9 @@ namespace gbe
     MPM.add(createInstructionCombiningPass());// Clean up after IPCP & DAE
     MPM.add(createCFGSimplificationPass());   // Clean up after IPCP & DAE
     MPM.add(createPruneEHPass());             // Remove dead EH info
+    MPM.add(createBarrierNodupPass(false));   // remove noduplicate fnAttr before inlining.
     MPM.add(createFunctionInliningPass(200000));
+    MPM.add(createBarrierNodupPass(true));    // restore noduplicate fnAttr after inlining.
     MPM.add(createFunctionAttrsPass());       // Set readonly/readnone attrs
 
     //MPM.add(createScalarReplAggregatesPass(64, true, -1, -1, 64))
diff --git a/backend/src/ocl_barrier.ll b/backend/src/ocl_barrier.ll
index 9f463478..4e55fcb7 100644
--- a/backend/src/ocl_barrier.ll
+++ b/backend/src/ocl_barrier.ll
@@ -6,9 +6,9 @@
 
 declare i32 @_get_local_mem_fence() nounwind alwaysinline
 declare i32 @_get_global_mem_fence() nounwind alwaysinline
-declare void @__gen_ocl_barrier_local() nounwind alwaysinline
-declare void @__gen_ocl_barrier_global() nounwind alwaysinline
-declare void @__gen_ocl_barrier_local_and_global() nounwind alwaysinline
+declare void @__gen_ocl_barrier_local() nounwind alwaysinline noduplicate
+declare void @__gen_ocl_barrier_global() nounwind alwaysinline noduplicate
+declare void @__gen_ocl_barrier_local_and_global() nounwind alwaysinline noduplicate
 
 define void @barrier(i32 %flags) nounwind noduplicate alwaysinline {
   %1 = icmp eq i32 %flags, 3