This patch adds a helper class (CGLoopInfo) for marking memory instructions with llvm.mem.parallel_loop_access metadata.

It also adds a simple initial version of codegen for pragma omp simd (it will change in the future to support all the clauses).

Differential revision: http://reviews.llvm.org/D3644

llvm-svn: 209411

1 files changed, 112 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGLoopInfo.cpp b/clang/lib/CodeGen/CGLoopInfo.cpp
new file mode 100644
index 00000000000..7b154b2d27e
--- /dev/null
+++ b/clang/lib/CodeGen/CGLoopInfo.cpp
@@ -0,0 +1,112 @@
+//===---- CGLoopInfo.cpp - LLVM CodeGen for loop metadata -*- C++ -*-------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CGLoopInfo.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Metadata.h"
+using namespace clang;
+using namespace CodeGen;
+using namespace llvm;
+
+static MDNode *createMetadata(LLVMContext &Ctx, const LoopAttributes &Attrs) {
+
+  if (!Attrs.IsParallel && Attrs.VectorizerWidth == 0 &&
+      Attrs.VectorizerUnroll == 0 &&
+      Attrs.VectorizerEnable == LoopAttributes::VecUnspecified)
+    return nullptr;
+
+  SmallVector<Value *, 4> Args;
+  // Reserve operand 0 for loop id self reference.
+  MDNode *TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode);
+
+  // Setting vectorizer.width
+  if (Attrs.VectorizerWidth > 0) {
+    Value *Vals[] = { MDString::get(Ctx, "llvm.vectorizer.width"),
+                      ConstantInt::get(Type::getInt32Ty(Ctx),
+                                       Attrs.VectorizerWidth) };
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // Setting vectorizer.unroll
+  if (Attrs.VectorizerUnroll > 0) {
+    Value *Vals[] = { MDString::get(Ctx, "llvm.vectorizer.unroll"),
+                      ConstantInt::get(Type::getInt32Ty(Ctx),
+                                       Attrs.VectorizerUnroll) };
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // Setting vectorizer.enable
+  if (Attrs.VectorizerEnable != LoopAttributes::VecUnspecified) {
+    Value *Vals[] = { MDString::get(Ctx, "llvm.vectorizer.enable"),
+                      ConstantInt::get(Type::getInt1Ty(Ctx),
+                                       (Attrs.VectorizerEnable ==
+                                        LoopAttributes::VecEnable)) };
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  MDNode *LoopID = MDNode::get(Ctx, Args);
+  assert(LoopID->use_empty() && "LoopID should not be used");
+
+  // Set the first operand to itself.
+  LoopID->replaceOperandWith(0, LoopID);
+  MDNode::deleteTemporary(TempNode);
+  return LoopID;
+}
+
+LoopAttributes::LoopAttributes(bool IsParallel)
+    : IsParallel(IsParallel), VectorizerEnable(LoopAttributes::VecUnspecified),
+      VectorizerWidth(0), VectorizerUnroll(0) {}
+
+void LoopAttributes::clear() {
+  IsParallel = false;
+  VectorizerWidth = 0;
+  VectorizerUnroll = 0;
+  VectorizerEnable = LoopAttributes::VecUnspecified;
+}
+
+LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs)
+    : LoopID(nullptr), Header(Header), Attrs(Attrs) {
+  LoopID = createMetadata(Header->getContext(), Attrs);
+}
+
+void LoopInfoStack::push(BasicBlock *Header) {
+  Active.push_back(LoopInfo(Header, StagedAttrs));
+  // Clear the attributes so nested loops do not inherit them.
+  StagedAttrs.clear();
+}
+
+void LoopInfoStack::pop() {
+  assert(!Active.empty() && "No active loops to pop");
+  Active.pop_back();
+}
+
+void LoopInfoStack::InsertHelper(Instruction *I) const {
+  if (!hasInfo())
+    return;
+
+  const LoopInfo &L = getInfo();
+  if (!L.getLoopID())
+    return;
+
+  if (TerminatorInst *TI = dyn_cast<TerminatorInst>(I)) {
+    for (unsigned i = 0, ie = TI->getNumSuccessors(); i < ie; ++i)
+      if (TI->getSuccessor(i) == L.getHeader()) {
+        TI->setMetadata("llvm.loop", L.getLoopID());
+        break;
+      }
+    return;
+  }
+
+  if (L.getAttributes().IsParallel && I->mayReadOrWriteMemory())
+    I->setMetadata("llvm.mem.parallel_loop_access", L.getLoopID());
+}