Update aosp/master LLVM for rebase to r256229

http://b/26987366

Change-Id: I1f29c4676a8abe633ab5707dded58d846c973d50

1 files changed, 175 insertions, 0 deletions

diff --git a/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp b/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
new file mode 100644
index 000000000000..0eefd57f1f2c
--- /dev/null
+++ b/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
@@ -0,0 +1,175 @@
+//===-- WebAssemblyFrameLowering.cpp - WebAssembly Frame Lowering ----------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file contains the WebAssembly implementation of
+/// TargetFrameLowering class.
+///
+/// On WebAssembly, there aren't a lot of things to do here. There are no
+/// callee-saved registers to save, and no spill slots.
+///
+/// The stack grows downward.
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssemblyFrameLowering.h"
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssemblyInstrInfo.h"
+#include "WebAssemblyMachineFunctionInfo.h"
+#include "WebAssemblySubtarget.h"
+#include "WebAssemblyTargetMachine.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-frame-info"
+
+// TODO: Implement a red zone?
+// TODO: wasm64
+// TODO: Prolog/epilog should be stackified too. This pass runs after register
+//       stackification, so we'll have to do it manually.
+// TODO: Emit TargetOpcode::CFI_INSTRUCTION instructions
+
+/// Return true if the specified function should have a dedicated frame pointer
+/// register.
+bool WebAssemblyFrameLowering::hasFP(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  const auto *RegInfo =
+      MF.getSubtarget<WebAssemblySubtarget>().getRegisterInfo();
+  return MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken() ||
+         MFI->hasStackMap() || MFI->hasPatchPoint() ||
+         RegInfo->needsStackRealignment(MF);
+}
+
+/// Under normal circumstances, when a frame pointer is not required, we reserve
+/// argument space for call sites in the function immediately on entry to the
+/// current function. This eliminates the need for add/sub sp brackets around
+/// call sites. Returns true if the call frame is included as part of the stack
+/// frame.
+bool WebAssemblyFrameLowering::hasReservedCallFrame(
+    const MachineFunction &MF) const {
+  return !MF.getFrameInfo()->hasVarSizedObjects();
+}
+
+
+/// Adjust the stack pointer by a constant amount.
+static void adjustStackPointer(unsigned StackSize,
+                               bool AdjustUp,
+                               MachineFunction& MF,
+                               MachineBasicBlock& MBB,
+                               const TargetInstrInfo* TII,
+                               MachineBasicBlock::iterator InsertPt,
+                               const DebugLoc& DL) {
+  auto &MRI = MF.getRegInfo();
+  unsigned SPReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+  auto *SPSymbol = MF.createExternalSymbolName("__stack_pointer");
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), SPReg)
+      .addExternalSymbol(SPSymbol);
+  // This MachinePointerInfo should reference __stack_pointer as well but
+  // doesn't because MachinePointerInfo() takes a GV which we don't have for
+  // __stack_pointer. TODO: check if PseudoSourceValue::ExternalSymbolCallEntry
+  // is appropriate instead. (likewise for EmitEpologue below)
+  auto *LoadMMO = new MachineMemOperand(MachinePointerInfo(),
+                                        MachineMemOperand::MOLoad, 4, 4);
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::LOAD_I32), SPReg)
+      .addImm(0)
+      .addReg(SPReg)
+      .addMemOperand(LoadMMO);
+  // Add/Subtract the frame size
+  unsigned OffsetReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+      .addImm(StackSize);
+  BuildMI(MBB, InsertPt, DL,
+          TII->get(AdjustUp ? WebAssembly::ADD_I32 : WebAssembly::SUB_I32),
+          WebAssembly::SP32)
+      .addReg(SPReg)
+      .addReg(OffsetReg);
+  // The SP32 register now has the new stacktop. Also write it back to memory.
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+      .addExternalSymbol(SPSymbol);
+  auto *MMO = new MachineMemOperand(MachinePointerInfo(),
+                                    MachineMemOperand::MOStore, 4, 4);
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::STORE_I32), WebAssembly::SP32)
+      .addImm(0)
+      .addReg(OffsetReg)
+      .addReg(WebAssembly::SP32)
+      .addMemOperand(MMO);
+}
+
+void WebAssemblyFrameLowering::eliminateCallFramePseudoInstr(
+    MachineFunction &MF, MachineBasicBlock &MBB,
+    MachineBasicBlock::iterator I) const {
+  const auto *TII =
+      static_cast<const WebAssemblyInstrInfo*>(MF.getSubtarget().getInstrInfo());
+  DebugLoc DL = I->getDebugLoc();
+  unsigned Opc = I->getOpcode();
+  bool IsDestroy = Opc == TII->getCallFrameDestroyOpcode();
+  unsigned Amount = I->getOperand(0).getImm();
+  if (Amount)
+    adjustStackPointer(Amount, IsDestroy, MF, MBB,
+                       TII, I, DL);
+  MBB.erase(I);
+}
+
+void WebAssemblyFrameLowering::emitPrologue(MachineFunction &MF,
+                                            MachineBasicBlock &MBB) const {
+  // TODO: Do ".setMIFlag(MachineInstr::FrameSetup)" on emitted instructions
+  auto *MFI = MF.getFrameInfo();
+  assert(MFI->getCalleeSavedInfo().empty() &&
+         "WebAssembly should not have callee-saved registers");
+  assert(!hasFP(MF) && "Functions needing frame pointers not yet supported");
+  uint64_t StackSize = MFI->getStackSize();
+  if (!StackSize && (!MFI->adjustsStack() || MFI->getMaxCallFrameSize() == 0))
+    return;
+
+  const auto *TII = MF.getSubtarget().getInstrInfo();
+
+  auto InsertPt = MBB.begin();
+  DebugLoc DL;
+
+  adjustStackPointer(StackSize, false, MF, MBB, TII, InsertPt, DL);
+}
+
+void WebAssemblyFrameLowering::emitEpilogue(MachineFunction &MF,
+                                            MachineBasicBlock &MBB) const {
+  uint64_t StackSize = MF.getFrameInfo()->getStackSize();
+  if (!StackSize)
+    return;
+  const auto *TII = MF.getSubtarget().getInstrInfo();
+  auto &MRI = MF.getRegInfo();
+  unsigned OffsetReg = MRI.createVirtualRegister(&WebAssembly::I32RegClass);
+  auto InsertPt = MBB.getFirstTerminator();
+  DebugLoc DL;
+
+  if (InsertPt != MBB.end()) {
+    DL = InsertPt->getDebugLoc();
+  }
+
+  // Restore the stack pointer. Without FP its value is just SP32 - stacksize
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+      .addImm(StackSize);
+  auto *SPSymbol = MF.createExternalSymbolName("__stack_pointer");
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::ADD_I32), WebAssembly::SP32)
+      .addReg(WebAssembly::SP32)
+      .addReg(OffsetReg);
+  // Re-use OffsetReg to hold the address of the stacktop
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::CONST_I32), OffsetReg)
+      .addExternalSymbol(SPSymbol);
+  auto *MMO = new MachineMemOperand(MachinePointerInfo(),
+                                    MachineMemOperand::MOStore, 4, 4);
+  BuildMI(MBB, InsertPt, DL, TII->get(WebAssembly::STORE_I32), WebAssembly::SP32)
+      .addImm(0)
+      .addReg(OffsetReg)
+      .addReg(WebAssembly::SP32)
+      .addMemOperand(MMO);
+}