ARM: lower tail calls correctly when using GHC calling convention.

Patch by Ben Gamari.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223055 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index 80add7a62d34e7c7d82dbb2e7d9cbd0b8d4e6c74..4f3012e9aafc8baebc933efb9ab09274a733dd5b 100644 (file)
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -612,11 +612,59 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF) const {
     AFI->setShouldRestoreSPFromFP(true);
 }
 
+// Resolve TCReturn pseudo-instruction
+void ARMFrameLowering::fixTCReturn(MachineFunction &MF,
+                                   MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
+  assert(MBBI->isReturn() && "Can only insert epilog into returning blocks");
+  unsigned RetOpcode = MBBI->getOpcode();
+  DebugLoc dl = MBBI->getDebugLoc();
+  const ARMBaseInstrInfo &TII =
+      *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
+
+  if (!(RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNri))
+    return;
+
+  // Tail call return: adjust the stack pointer and jump to callee.
+  MBBI = MBB.getLastNonDebugInstr();
+  MachineOperand &JumpTarget = MBBI->getOperand(0);
+
+  // Jump to label or value in register.
+  if (RetOpcode == ARM::TCRETURNdi) {
+    unsigned TCOpcode = STI.isThumb() ?
+             (STI.isTargetMachO() ? ARM::tTAILJMPd : ARM::tTAILJMPdND) :
+             ARM::TAILJMPd;
+    MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(TCOpcode));
+    if (JumpTarget.isGlobal())
+      MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
+                           JumpTarget.getTargetFlags());
+    else {
+      assert(JumpTarget.isSymbol());
+      MIB.addExternalSymbol(JumpTarget.getSymbolName(),
+                            JumpTarget.getTargetFlags());
+    }
+
+    // Add the default predicate in Thumb mode.
+    if (STI.isThumb()) MIB.addImm(ARMCC::AL).addReg(0);
+  } else if (RetOpcode == ARM::TCRETURNri) {
+    BuildMI(MBB, MBBI, dl,
+            TII.get(STI.isThumb() ? ARM::tTAILJMPr : ARM::TAILJMPr)).
+      addReg(JumpTarget.getReg(), RegState::Kill);
+  }
+
+  MachineInstr *NewMI = std::prev(MBBI);
+  for (unsigned i = 1, e = MBBI->getNumOperands(); i != e; ++i)
+    NewMI->addOperand(MBBI->getOperand(i));
+
+  // Delete the pseudo instruction TCRETURN.
+  MBB.erase(MBBI);
+  MBBI = NewMI;
+}
+
 void ARMFrameLowering::emitEpilogue(MachineFunction &MF,
                                     MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
   assert(MBBI->isReturn() && "Can only insert epilog into returning blocks");
-  unsigned RetOpcode = MBBI->getOpcode();
   DebugLoc dl = MBBI->getDebugLoc();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
@@ -637,8 +685,10 @@ void ARMFrameLowering::emitEpilogue(MachineFunction &MF,
 
   // All calls are tail calls in GHC calling conv, and functions have no
   // prologue/epilogue.
-  if (MF.getFunction()->getCallingConv() == CallingConv::GHC)
+  if (MF.getFunction()->getCallingConv() == CallingConv::GHC) {
+    fixTCReturn(MF, MBB);
     return;
+  }
 
   if (!AFI->hasStackFrame()) {
     if (NumBytes - ArgRegsSaveSize != 0)
@@ -717,42 +767,7 @@ void ARMFrameLowering::emitEpilogue(MachineFunction &MF,
     if (AFI->getGPRCalleeSavedArea1Size()) MBBI++;
   }
 
-  if (RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNri) {
-    // Tail call return: adjust the stack pointer and jump to callee.
-    MBBI = MBB.getLastNonDebugInstr();
-    MachineOperand &JumpTarget = MBBI->getOperand(0);
-
-    // Jump to label or value in register.
-    if (RetOpcode == ARM::TCRETURNdi) {
-      unsigned TCOpcode = STI.isThumb() ?
-               (STI.isTargetMachO() ? ARM::tTAILJMPd : ARM::tTAILJMPdND) :
-               ARM::TAILJMPd;
-      MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(TCOpcode));
-      if (JumpTarget.isGlobal())
-        MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
-                             JumpTarget.getTargetFlags());
-      else {
-        assert(JumpTarget.isSymbol());
-        MIB.addExternalSymbol(JumpTarget.getSymbolName(),
-                              JumpTarget.getTargetFlags());
-      }
-
-      // Add the default predicate in Thumb mode.
-      if (STI.isThumb()) MIB.addImm(ARMCC::AL).addReg(0);
-    } else if (RetOpcode == ARM::TCRETURNri) {
-      BuildMI(MBB, MBBI, dl,
-              TII.get(STI.isThumb() ? ARM::tTAILJMPr : ARM::TAILJMPr)).
-        addReg(JumpTarget.getReg(), RegState::Kill);
-    }
-
-    MachineInstr *NewMI = std::prev(MBBI);
-    for (unsigned i = 1, e = MBBI->getNumOperands(); i != e; ++i)
-      NewMI->addOperand(MBBI->getOperand(i));
-
-    // Delete the pseudo instruction TCRETURN.
-    MBB.erase(MBBI);
-    MBBI = NewMI;
-  }
+  fixTCReturn(MF, MBB);
 
   if (ArgRegsSaveSize)
     emitSPUpdate(isARM, MBB, MBBI, dl, TII, ArgRegsSaveSize);

diff --git a/lib/Target/ARM/ARMFrameLowering.h b/lib/Target/ARM/ARMFrameLowering.h
index a83b7730ff93d1d5b873a5a4aca7e6329bcf04c2..b7be43642ad058d61d9663a20732f0b83a2eb242 100644 (file)
--- a/lib/Target/ARM/ARMFrameLowering.h
+++ b/lib/Target/ARM/ARMFrameLowering.h
@@ -31,6 +31,8 @@ public:
   void emitPrologue(MachineFunction &MF) const override;
   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
 
+  void fixTCReturn(MachineFunction &MF, MachineBasicBlock &MBB) const;
+
   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MI,
                                  const std::vector<CalleeSavedInfo> &CSI,

diff --git a/test/CodeGen/ARM/ghc-tcreturn-lowered.ll b/test/CodeGen/ARM/ghc-tcreturn-lowered.ll
new file mode 100644 (file)
index 0000000..6d2564b
--- /dev/null
+++ b/test/CodeGen/ARM/ghc-tcreturn-lowered.ll
@@ -0,0 +1,21 @@
+; RUN: llc -mtriple=thumbv7-eabi -o - %s | FileCheck %s
+
+declare cc 10 void @g()
+
+define cc 10 void @test_direct_tail() {
+; CHECK-LABEL: test_direct_tail:
+; CHECK: b g
+
+  tail call cc10 void @g()
+  ret void
+}
+
+@ind_func = global void()* zeroinitializer
+
+define cc 10 void @test_indirect_tail() {
+; CHECK-LABEL: test_indirect_tail:
+; CHECK: bx {{r[0-9]+}}
+  %func = load void()** @ind_func
+  tail call cc10 void()* %func()
+  ret void
+}