1 files changed, 109 insertions, 8 deletions

diff --git a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
index e4ca82e..0eefd57 100644
--- a/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
+++ b/contrib/llvm/lib/Target/WebAssembly/WebAssemblyFrameLowering.cpp
@@ -35,11 +35,20 @@ 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 {
-  llvm_unreachable("TODO: implement hasFP");
+  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
@@ -52,23 +61,115 @@ bool WebAssemblyFrameLowering::hasReservedCallFrame(
   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 {
-  llvm_unreachable("TODO: implement eliminateCallFramePseudoInstr");
+  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 {
-  llvm_unreachable("TODO: implement emitPrologue");
+  // 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 {
-  llvm_unreachable("TODO: implement emitEpilogue");
-}
+  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();
+  }
 
-void WebAssemblyFrameLowering::processFunctionBeforeCalleeSavedScan(
-    MachineFunction &MF, RegScavenger *RS) const {
-  llvm_unreachable("TODO: implement processFunctionBeforeCalleeSavedScan");
+  // 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);
 }