1 files changed, 138 insertions, 0 deletions
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp b/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp
new file mode 100644
index 000000000000..bba132c3bc46
--- /dev/null
+++ b/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp
@@ -0,0 +1,138 @@
+//===- AMDGPUAliasAnalysis ------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This is the AMGPU address space based alias analysis pass.
+//===----------------------------------------------------------------------===//
+
+#include "AMDGPUAliasAnalysis.h"
+#include "AMDGPU.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/MemoryLocation.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Argument.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/Value.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <cassert>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "amdgpu-aa"
+
+// Register this pass...
+char AMDGPUAAWrapperPass::ID = 0;
+char AMDGPUExternalAAWrapper::ID = 0;
+
+INITIALIZE_PASS(AMDGPUAAWrapperPass, "amdgpu-aa",
+                "AMDGPU Address space based Alias Analysis", false, true)
+
+INITIALIZE_PASS(AMDGPUExternalAAWrapper, "amdgpu-aa-wrapper",
+                "AMDGPU Address space based Alias Analysis Wrapper", false, true)
+
+ImmutablePass *llvm::createAMDGPUAAWrapperPass() {
+  return new AMDGPUAAWrapperPass();
+}
+
+ImmutablePass *llvm::createAMDGPUExternalAAWrapperPass() {
+  return new AMDGPUExternalAAWrapper();
+}
+
+void AMDGPUAAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+}
+
+// These arrays are indexed by address space value enum elements 0 ... to 7
+static const AliasResult ASAliasRules[8][8] = {
+  /*                    Flat       Global    Region    Group     Constant  Private   Constant 32-bit  Buffer Fat Ptr */
+  /* Flat     */        {MayAlias, MayAlias, NoAlias,  MayAlias, MayAlias, MayAlias, MayAlias,        MayAlias},
+  /* Global   */        {MayAlias, MayAlias, NoAlias , NoAlias , MayAlias, NoAlias , MayAlias,        MayAlias},
+  /* Region   */        {NoAlias,  NoAlias , MayAlias, NoAlias , NoAlias,  NoAlias , NoAlias,         NoAlias},
+  /* Group    */        {MayAlias, NoAlias , NoAlias , MayAlias, NoAlias , NoAlias , NoAlias ,        NoAlias},
+  /* Constant */        {MayAlias, MayAlias, NoAlias,  NoAlias , NoAlias , NoAlias , MayAlias,        MayAlias},
+  /* Private  */        {MayAlias, NoAlias , NoAlias , NoAlias , NoAlias , MayAlias, NoAlias ,        NoAlias},
+  /* Constant 32-bit */ {MayAlias, MayAlias, NoAlias,  NoAlias , MayAlias, NoAlias , NoAlias ,        MayAlias},
+  /* Buffer Fat Ptr  */ {MayAlias, MayAlias, NoAlias , NoAlias , MayAlias, NoAlias , MayAlias,        MayAlias}
+};
+
+static AliasResult getAliasResult(unsigned AS1, unsigned AS2) {
+  static_assert(AMDGPUAS::MAX_AMDGPU_ADDRESS <= 7, "Addr space out of range");
+
+  if (AS1 > AMDGPUAS::MAX_AMDGPU_ADDRESS || AS2 > AMDGPUAS::MAX_AMDGPU_ADDRESS)
+    return MayAlias;
+
+  return ASAliasRules[AS1][AS2];
+}
+
+AliasResult AMDGPUAAResult::alias(const MemoryLocation &LocA,
+                                  const MemoryLocation &LocB,
+                                  AAQueryInfo &AAQI) {
+  unsigned asA = LocA.Ptr->getType()->getPointerAddressSpace();
+  unsigned asB = LocB.Ptr->getType()->getPointerAddressSpace();
+
+  AliasResult Result = getAliasResult(asA, asB);
+  if (Result == NoAlias)
+    return Result;
+
+  // Forward the query to the next alias analysis.
+  return AAResultBase::alias(LocA, LocB, AAQI);
+}
+
+bool AMDGPUAAResult::pointsToConstantMemory(const MemoryLocation &Loc,
+                                            AAQueryInfo &AAQI, bool OrLocal) {
+  const Value *Base = GetUnderlyingObject(Loc.Ptr, DL);
+  unsigned AS = Base->getType()->getPointerAddressSpace();
+  if (AS == AMDGPUAS::CONSTANT_ADDRESS ||
+      AS == AMDGPUAS::CONSTANT_ADDRESS_32BIT) {
+    return true;
+  }
+
+  if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
+    if (GV->isConstant())
+      return true;
+  } else if (const Argument *Arg = dyn_cast<Argument>(Base)) {
+    const Function *F = Arg->getParent();
+
+    // Only assume constant memory for arguments on kernels.
+    switch (F->getCallingConv()) {
+    default:
+      return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
+    case CallingConv::AMDGPU_LS:
+    case CallingConv::AMDGPU_HS:
+    case CallingConv::AMDGPU_ES:
+    case CallingConv::AMDGPU_GS:
+    case CallingConv::AMDGPU_VS:
+    case CallingConv::AMDGPU_PS:
+    case CallingConv::AMDGPU_CS:
+    case CallingConv::AMDGPU_KERNEL:
+    case CallingConv::SPIR_KERNEL:
+      break;
+    }
+
+    unsigned ArgNo = Arg->getArgNo();
+    /* On an argument, ReadOnly attribute indicates that the function does
+       not write through this pointer argument, even though it may write
+       to the memory that the pointer points to.
+       On an argument, ReadNone attribute indicates that the function does
+       not dereference that pointer argument, even though it may read or write
+       the memory that the pointer points to if accessed through other pointers.
+     */
+    if (F->hasParamAttribute(ArgNo, Attribute::NoAlias) &&
+        (F->hasParamAttribute(ArgNo, Attribute::ReadNone) ||
+         F->hasParamAttribute(ArgNo, Attribute::ReadOnly))) {
+      return true;
+    }
+  }
+  return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
+}