[SystemZ] [z/OS] Add support for generating huge (1 MiB) stack frames…

… in XPLINK64 This patch extends support for generating huge stack frames on 64-bit XPLINK by implementing the ABI-mandated call to the stack extension routine. Reviewed By: uweigand Differential Revision: https://reviews.llvm.org/D120450
llvm · Feb 25, 2022 · eb3e09c · eb3e09c
1 parent b3ebcd7
commit eb3e09c
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Showing 10 changed files with 119 additions and 11 deletions.
diff --git a/llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp b/llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp
@@ -262,6 +262,13 @@ void SystemZAsmPrinter::emitInstruction(const MachineInstr *MI) {
     emitCallInformation(CallType::BASR76);
     return;
 
+  case SystemZ::CallBASR_STACKEXT:
+    EmitToStreamer(*OutStreamer, MCInstBuilder(SystemZ::BASR)
+                                     .addReg(SystemZ::R3D)
+                                     .addReg(MI->getOperand(0).getReg()));
+    emitCallInformation(CallType::BASR33);
+    return;
+
   case SystemZ::CallBRASL:
     LoweredMI = MCInstBuilder(SystemZ::BRASL)
       .addReg(SystemZ::R14D)

diff --git a/llvm/lib/Target/SystemZ/SystemZFrameLowering.cpp b/llvm/lib/Target/SystemZ/SystemZFrameLowering.cpp
@@ -1153,12 +1153,6 @@ void SystemZXPLINKFrameLowering::emitPrologue(MachineFunction &MF,
   MFFrame.setStackSize(MFFrame.getStackSize() + Regs.getCallFrameSize());
   uint64_t StackSize = MFFrame.getStackSize();
 
-  // FIXME: Implement support for large stack sizes, when the stack extension
-  // routine needs to be called.
-  if (StackSize > 1024 * 1024) {
-    llvm_unreachable("Huge Stack Frame not yet supported on z/OS");
-  }
-
   if (ZFI->getSpillGPRRegs().LowGPR) {
     // Skip over the GPR saves.
     if ((MBBI != MBB.end()) && ((MBBI->getOpcode() == SystemZ::STMG))) {
@@ -1201,6 +1195,18 @@ void SystemZXPLINKFrameLowering::emitPrologue(MachineFunction &MF,
 
     emitIncrement(MBB, InsertPt, DL, Regs.getStackPointerRegister(), Delta,
                   ZII);
+
+    // If the requested stack size is larger than the guard page, then we need
+    // to check if we need to call the stack extender. This requires adding a
+    // conditional branch, but splitting the prologue block is not possible at
+    // this point since it would invalidate the SaveBlocks / RestoreBlocks sets
+    // of PEI in the single block function case. Build a pseudo to be handled
+    // later by inlineStackProbe().
+    const uint64_t GuardPageSize = 1024 * 1024;
+    if (StackSize > GuardPageSize) {
+      assert(StoreInstr && "Wrong insertion point");
+      BuildMI(MBB, InsertPt, DL, ZII->get(SystemZ::XPLINK_STACKALLOC));
+    }
   }
 
   if (HasFP) {
@@ -1239,6 +1245,74 @@ void SystemZXPLINKFrameLowering::emitEpilogue(MachineFunction &MF,
   }
 }
 
+// Emit a compare of the stack pointer against the stack floor, and a call to
+// the LE stack extender if needed.
+void SystemZXPLINKFrameLowering::inlineStackProbe(
+    MachineFunction &MF, MachineBasicBlock &PrologMBB) const {
+  auto *ZII =
+      static_cast<const SystemZInstrInfo *>(MF.getSubtarget().getInstrInfo());
+
+  MachineInstr *StackAllocMI = nullptr;
+  for (MachineInstr &MI : PrologMBB)
+    if (MI.getOpcode() == SystemZ::XPLINK_STACKALLOC) {
+      StackAllocMI = &MI;
+      break;
+    }
+  if (StackAllocMI == nullptr)
+    return;
+
+  MachineBasicBlock &MBB = PrologMBB;
+  const DebugLoc DL = StackAllocMI->getDebugLoc();
+
+  // The 2nd half of block MBB after split.
+  MachineBasicBlock *NextMBB;
+
+  // Add new basic block for the call to the stack overflow function.
+  MachineBasicBlock *StackExtMBB =
+      MF.CreateMachineBasicBlock(MBB.getBasicBlock());
+  MF.push_back(StackExtMBB);
+
+  // LG r3,72(,r3)
+  BuildMI(StackExtMBB, DL, ZII->get(SystemZ::LG), SystemZ::R3D)
+      .addReg(SystemZ::R3D)
+      .addImm(72)
+      .addReg(0);
+  // BASR r3,r3
+  BuildMI(StackExtMBB, DL, ZII->get(SystemZ::CallBASR_STACKEXT))
+      .addReg(SystemZ::R3D);
+
+  // LLGT r3,1208
+  BuildMI(MBB, StackAllocMI, DL, ZII->get(SystemZ::LLGT), SystemZ::R3D)
+      .addReg(0)
+      .addImm(1208)
+      .addReg(0);
+  // CG r4,64(,r3)
+  BuildMI(MBB, StackAllocMI, DL, ZII->get(SystemZ::CG))
+      .addReg(SystemZ::R4D)
+      .addReg(SystemZ::R3D)
+      .addImm(64)
+      .addReg(0);
+  // JLL b'0100',F'37'
+  BuildMI(MBB, StackAllocMI, DL, ZII->get(SystemZ::BRC))
+      .addImm(SystemZ::CCMASK_ICMP)
+      .addImm(SystemZ::CCMASK_CMP_LT)
+      .addMBB(StackExtMBB);
+
+  NextMBB = SystemZ::splitBlockBefore(StackAllocMI, &MBB);
+  MBB.addSuccessor(NextMBB);
+  MBB.addSuccessor(StackExtMBB);
+
+  // Add jump back from stack extension BB.
+  BuildMI(StackExtMBB, DL, ZII->get(SystemZ::J)).addMBB(NextMBB);
+  StackExtMBB->addSuccessor(NextMBB);
+
+  StackAllocMI->eraseFromParent();
+
+  // Compute the live-in lists for the new blocks.
+  recomputeLiveIns(*NextMBB);
+  recomputeLiveIns(*StackExtMBB);
+}
+
 bool SystemZXPLINKFrameLowering::hasFP(const MachineFunction &MF) const {
   return (MF.getFrameInfo().hasVarSizedObjects());
 }

diff --git a/llvm/lib/Target/SystemZ/SystemZFrameLowering.h b/llvm/lib/Target/SystemZ/SystemZFrameLowering.h
@@ -127,6 +127,9 @@ class SystemZXPLINKFrameLowering : public SystemZFrameLowering {
 
   void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
 
+  void inlineStackProbe(MachineFunction &MF,
+                        MachineBasicBlock &PrologMBB) const override;
+
   bool hasFP(const MachineFunction &MF) const override;
 
   void processFunctionBeforeFrameFinalized(MachineFunction &MF,

diff --git a/llvm/lib/Target/SystemZ/SystemZInstrInfo.td b/llvm/lib/Target/SystemZ/SystemZInstrInfo.td
@@ -42,6 +42,10 @@ let Defs = [R1D, R15D, CC], Uses = [R15D], hasNoSchedulingInfo = 1,
     hasSideEffects = 1 in
   def PROBED_STACKALLOC : Pseudo<(outs), (ins i64imm:$stacksize), []>;
 
+let Defs = [R3D, CC], Uses = [R3D, R4D], hasNoSchedulingInfo = 1,
+    hasSideEffects = 1 in
+  def XPLINK_STACKALLOC : Pseudo<(outs), (ins), []>;
+
 //===----------------------------------------------------------------------===//
 // Branch instructions
 //===----------------------------------------------------------------------===//
@@ -285,6 +289,10 @@ let Predicates = [IsTargetXPLINK64] in {
     def CallBASR_XPLINK64  : Alias<4, (outs), (ins ADDR64:$R2, variable_ops),
                           [(z_call ADDR64:$R2)]>;
   }
+
+  let isCall = 1, Defs = [R3D, CC], Uses = [FPC] in {
+    def CallBASR_STACKEXT  : Alias<4, (outs), (ins ADDR64:$R2), []>;
+  }
 }
 
 // Regular calls.

diff --git a/llvm/lib/Target/SystemZ/SystemZScheduleZ13.td b/llvm/lib/Target/SystemZ/SystemZScheduleZ13.td
@@ -168,7 +168,7 @@ def : InstRW<[WLat1, FXb, LSU, NormalGr], (instregex "CL(G)?T(Asm.*)?$")>;
 // Call
 def : InstRW<[WLat1, VBU, FXa2, GroupAlone], (instregex "(Call)?BRAS$")>;
 def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BRASL(_XPLINK64)?$")>;
-def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64)?$")>;
+def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64|_STACKEXT)?$")>;
 def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "TLS_(G|L)DCALL$")>;
 
 // Return

diff --git a/llvm/lib/Target/SystemZ/SystemZScheduleZ14.td b/llvm/lib/Target/SystemZ/SystemZScheduleZ14.td
@@ -169,7 +169,7 @@ def : InstRW<[WLat1, FXb, LSU, NormalGr], (instregex "CL(G)?T(Asm.*)?$")>;
 // Call
 def : InstRW<[WLat1, VBU, FXa2, GroupAlone], (instregex "(Call)?BRAS$")>;
 def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BRASL(_XPLINK64)?$")>;
-def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64)?$")>;
+def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64|_STACKEXT)?$")>;
 def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "TLS_(G|L)DCALL$")>;
 
 // Return

diff --git a/llvm/lib/Target/SystemZ/SystemZScheduleZ15.td b/llvm/lib/Target/SystemZ/SystemZScheduleZ15.td
@@ -169,7 +169,7 @@ def : InstRW<[WLat1, FXb, LSU, NormalGr], (instregex "CL(G)?T(Asm.*)?$")>;
 // Call
 def : InstRW<[WLat1, VBU, FXa2, GroupAlone], (instregex "(Call)?BRAS$")>;
 def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BRASL(_XPLINK64)?$")>;
-def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64)?$")>;
+def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64|_STACKEXT)?$")>;
 def : InstRW<[WLat1, FXa2, FXb, GroupAlone], (instregex "TLS_(G|L)DCALL$")>;
 
 // Return

diff --git a/llvm/lib/Target/SystemZ/SystemZScheduleZ196.td b/llvm/lib/Target/SystemZ/SystemZScheduleZ196.td
@@ -147,7 +147,7 @@ def : InstRW<[WLat1, FXU, NormalGr], (instregex "CL(F|G)IT(Asm.*)?$")>;
 // Call
 def : InstRW<[WLat1, LSU, FXU2, GroupAlone], (instregex "(Call)?BRAS$")>;
 def : InstRW<[WLat1, LSU, FXU2, GroupAlone], (instregex "(Call)?BRASL(_XPLINK64)?$")>;
-def : InstRW<[WLat1, LSU, FXU2, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64)?$")>;
+def : InstRW<[WLat1, LSU, FXU2, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64|_STACKEXT)?$")>;
 def : InstRW<[WLat1, LSU, FXU2, GroupAlone], (instregex "TLS_(G|L)DCALL$")>;
 
 // Return

diff --git a/llvm/lib/Target/SystemZ/SystemZScheduleZEC12.td b/llvm/lib/Target/SystemZ/SystemZScheduleZEC12.td
@@ -152,7 +152,7 @@ def : InstRW<[WLat1, FXU, LSU, NormalGr], (instregex "CL(G)?T(Asm.*)?$")>;
 // Call
 def : InstRW<[WLat1, FXU2, VBU, GroupAlone], (instregex "(Call)?BRAS$")>;
 def : InstRW<[WLat1, FXU2, LSU, GroupAlone], (instregex "(Call)?BRASL(_XPLINK64)?$")>;
-def : InstRW<[WLat1, FXU2, LSU, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64)?$")>;
+def : InstRW<[WLat1, FXU2, LSU, GroupAlone], (instregex "(Call)?BAS(R)?(_XPLINK64|_STACKEXT)?$")>;
 def : InstRW<[WLat1, FXU2, LSU, GroupAlone], (instregex "TLS_(G|L)DCALL$")>;
 
 // Return

diff --git a/llvm/test/CodeGen/SystemZ/zos-prologue-epilog.ll b/llvm/test/CodeGen/SystemZ/zos-prologue-epilog.ll
@@ -312,6 +312,22 @@ define i64 @func5(i64 %n) {
   ret i64 %call
 }
 
+; CHECK-LABEL: large_stack
+; CHECK64: agfi  4, -1048768
+; CHECK64-NEXT: llgt  3, 1208
+; CHECK64-NEXT: cg  4, 64(3)
+; CHECK64-NEXT: jhe
+; CHECK64: * %bb.1:
+; CHECK64: lg  3, 72(3)
+; CHECK64: basr  3, 3
+; CHECK64: stmg  6, 7, 2064(4)
+define void @large_stack() {
+  %arr = alloca [131072 x i64], align 8
+  %ptr = bitcast [131072 x i64]* %arr to i8*
+  call i64 (i8*) @fun1(i8* %ptr)
+  ret void
+}
+
 declare i64 @fun(i64 %arg0)
 declare i64 @fun1(i8* %ptr)
 declare i64 @fun2(i64 %n, i64* %arr0, i64* %arr1)