Imported Upstream version 5.18.0.161

Former-commit-id: 4db48158d3a35497b8f118ab21b5f08ac3d86d98

external/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp

@@ -0,0 +1,159 @@
+//===- AMDGPUAliasAnalysis ------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \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;
+
+INITIALIZE_PASS(AMDGPUAAWrapperPass, "amdgpu-aa",
+                "AMDGPU Address space based Alias Analysis", false, true)
+
+ImmutablePass *llvm::createAMDGPUAAWrapperPass() {
+  return new AMDGPUAAWrapperPass();
+}
+
+void AMDGPUAAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+}
+
+// Must match the table in getAliasResult.
+AMDGPUAAResult::ASAliasRulesTy::ASAliasRulesTy(AMDGPUAS AS_, Triple::ArchType Arch_)
+  : Arch(Arch_), AS(AS_) {
+  // These arrarys are indexed by address space value
+  // enum elements 0 ... to 5
+  static const AliasResult ASAliasRulesPrivIsZero[6][6] = {
+  /*             Private    Global    Constant  Group     Flat      Region*/
+  /* Private  */ {MayAlias, NoAlias , NoAlias , NoAlias , MayAlias, NoAlias},
+  /* Global   */ {NoAlias , MayAlias, NoAlias , NoAlias , MayAlias, NoAlias},
+  /* Constant */ {NoAlias , NoAlias , MayAlias, NoAlias , MayAlias, NoAlias},
+  /* Group    */ {NoAlias , NoAlias , NoAlias , MayAlias, MayAlias, NoAlias},
+  /* Flat     */ {MayAlias, MayAlias, MayAlias, MayAlias, MayAlias, MayAlias},
+  /* Region   */ {NoAlias , NoAlias , NoAlias , NoAlias , MayAlias, MayAlias}
+  };
+  static const AliasResult ASAliasRulesGenIsZero[6][6] = {
+  /*             Flat       Global    Constant  Group     Region    Private */
+  /* Flat     */ {MayAlias, MayAlias, MayAlias, MayAlias, MayAlias, MayAlias},
+  /* Global   */ {MayAlias, MayAlias, NoAlias , NoAlias , NoAlias , NoAlias},
+  /* Constant */ {MayAlias, NoAlias , MayAlias, NoAlias , NoAlias,  NoAlias},
+  /* Group    */ {MayAlias, NoAlias , NoAlias , MayAlias, NoAlias , NoAlias},
+  /* Region   */ {MayAlias, NoAlias , NoAlias , NoAlias,  MayAlias, NoAlias},
+  /* Private  */ {MayAlias, NoAlias , NoAlias , NoAlias , NoAlias , MayAlias}
+  };
+  assert(AS.MAX_COMMON_ADDRESS <= 5);
+  if (AS.FLAT_ADDRESS == 0) {
+    assert(AS.GLOBAL_ADDRESS   == 1 &&
+           AS.REGION_ADDRESS   == 4 &&
+           AS.LOCAL_ADDRESS    == 3 &&
+           AS.CONSTANT_ADDRESS == 2 &&
+           AS.PRIVATE_ADDRESS  == 5);
+    ASAliasRules = &ASAliasRulesGenIsZero;
+  } else {
+    assert(AS.PRIVATE_ADDRESS  == 0 &&
+           AS.GLOBAL_ADDRESS   == 1 &&
+           AS.CONSTANT_ADDRESS == 2 &&
+           AS.LOCAL_ADDRESS    == 3 &&
+           AS.FLAT_ADDRESS     == 4 &&
+           AS.REGION_ADDRESS   == 5);
+    ASAliasRules = &ASAliasRulesPrivIsZero;
+  }
+}
+
+AliasResult AMDGPUAAResult::ASAliasRulesTy::getAliasResult(unsigned AS1,
+    unsigned AS2) const {
+  if (AS1 > AS.MAX_COMMON_ADDRESS || AS2 > AS.MAX_COMMON_ADDRESS) {
+    if (Arch == Triple::amdgcn)
+      report_fatal_error("Pointer address space out of range");
+    return AS1 == AS2 ? MayAlias : NoAlias;
+  }
+
+  return (*ASAliasRules)[AS1][AS2];
+}
+
+AliasResult AMDGPUAAResult::alias(const MemoryLocation &LocA,
+                                  const MemoryLocation &LocB) {
+  unsigned asA = LocA.Ptr->getType()->getPointerAddressSpace();
+  unsigned asB = LocB.Ptr->getType()->getPointerAddressSpace();
+
+  AliasResult Result = ASAliasRules.getAliasResult(asA, asB);
+  if (Result == NoAlias) return Result;
+
+  // Forward the query to the next alias analysis.
+  return AAResultBase::alias(LocA, LocB);
+}
+
+bool AMDGPUAAResult::pointsToConstantMemory(const MemoryLocation &Loc,
+                                            bool OrLocal) {
+  const Value *Base = GetUnderlyingObject(Loc.Ptr, DL);
+
+  if (Base->getType()->getPointerAddressSpace() == AS.CONSTANT_ADDRESS) {
+    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, 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, OrLocal);
+}