Implement ADJCALLSTACKUP and ADJCALLSTACKDOWN

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167107 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 67 insertions, 9 deletions

diff --git a/lib/Target/Mips/Mips16FrameLowering.cpp b/lib/Target/Mips/Mips16FrameLowering.cpp
index 74cffd202c..4e6b21feb5 100644
--- a/lib/Target/Mips/Mips16FrameLowering.cpp
+++ b/lib/Target/Mips/Mips16FrameLowering.cpp
@@ -115,8 +115,10 @@ bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
 
 bool
 Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
-  // FIXME: implement.
-  return true;
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  // Reserve call frame if the size of the maximum call frame fits into 15-bit
+  // immediate field and there are no variable sized objects on the stack.
+  return isInt<15>(MFI->getMaxCallFrameSize()) && !MFI->hasVarSizedObjects();
 }
 
 void Mips16FrameLowering::
diff --git a/lib/Target/Mips/Mips16InstrInfo.cpp b/lib/Target/Mips/Mips16InstrInfo.cpp
index fa0876a4eb..619646b317 100644
--- a/lib/Target/Mips/Mips16InstrInfo.cpp
+++ b/lib/Target/Mips/Mips16InstrInfo.cpp
@@ -26,7 +26,7 @@ using namespace llvm;
 
 Mips16InstrInfo::Mips16InstrInfo(MipsTargetMachine &tm)
   : MipsInstrInfo(tm, Mips::BimmX16),
-    RI(*tm.getSubtargetImpl()) {}
+    RI(*tm.getSubtargetImpl(), *this) {}
 
 const MipsRegisterInfo &Mips16InstrInfo::getRegisterInfo() const {
   return RI;
@@ -160,6 +160,22 @@ unsigned Mips16InstrInfo::GetOppositeBranchOpc(unsigned Opc) const {
   return 0;
 }
 
+/// Adjust SP by Amount bytes.
+void Mips16InstrInfo::adjustStackPtr(unsigned SP, int64_t Amount,
+                                     MachineBasicBlock &MBB,
+                                     MachineBasicBlock::iterator I) const {
+  DebugLoc DL = I != MBB.end() ? I->getDebugLoc() : DebugLoc();
+  if (isInt<16>(Amount)) {
+    if (Amount < 0)
+      BuildMI(MBB, I, DL, get(Mips::SaveDecSpF16)). addImm(-Amount);
+    else if (Amount > 0)
+      BuildMI(MBB, I, DL, get(Mips::RestoreIncSpF16)).addImm(Amount);
+  }
+  else
+    // not implemented for large values yet
+    assert(false && "adjust stack pointer amount exceeded");
+}
+
 unsigned Mips16InstrInfo::GetAnalyzableBrOpc(unsigned Opc) const {
   return (Opc == Mips::BeqzRxImmX16   || Opc == Mips::BimmX16  ||
           Opc == Mips::BnezRxImmX16   || Opc == Mips::BteqzX16 ||
diff --git a/lib/Target/Mips/Mips16InstrInfo.h b/lib/Target/Mips/Mips16InstrInfo.h
index 260c5b69b2..e06ccfe61c 100644
--- a/lib/Target/Mips/Mips16InstrInfo.h
+++ b/lib/Target/Mips/Mips16InstrInfo.h
@@ -64,6 +64,10 @@ public:
 
   virtual unsigned GetOppositeBranchOpc(unsigned Opc) const;
 
+  /// Adjust SP by Amount bytes.
+  void adjustStackPtr(unsigned SP, int64_t Amount, MachineBasicBlock &MBB,
+                      MachineBasicBlock::iterator I) const;
+
 private:
   virtual unsigned GetAnalyzableBrOpc(unsigned Opc) const;
 
diff --git a/lib/Target/Mips/Mips16InstrInfo.td b/lib/Target/Mips/Mips16InstrInfo.td
index 5f8af05f0c..5defc75ea6 100644
--- a/lib/Target/Mips/Mips16InstrInfo.td
+++ b/lib/Target/Mips/Mips16InstrInfo.td
@@ -686,7 +686,17 @@ def OrRxRxRy16: FRxRxRy16_ins<0b01101, "or", IIAlu>, ArithLogic16Defs<1>;
 let ra=1, s=0,s0=1,s1=1 in
 def RestoreRaF16:
   FI8_SVRS16<0b1, (outs), (ins uimm16:$frame_size),
-             "restore \t$$ra,  $$s0, $$s1, $frame_size", [], IILoad >, MayLoad {
+             "restore\t$$ra,  $$s0, $$s1, $frame_size", [], IILoad >, MayLoad {
+  let isCodeGenOnly = 1;
+}
+
+// Use Restore to increment SP since SP is not a Mip 16 register, this
+// is an easy way to do that which does not require a register.
+//
+let ra=0, s=0,s0=0,s1=0 in
+def RestoreIncSpF16:
+  FI8_SVRS16<0b1, (outs), (ins uimm16:$frame_size),
+             "restore\t$frame_size", [], IILoad >, MayLoad {
   let isCodeGenOnly = 1;
 }
 
@@ -700,7 +710,18 @@ def RestoreRaF16:
 let ra=1, s=1,s0=1,s1=1 in
 def SaveRaF16:
   FI8_SVRS16<0b1, (outs), (ins uimm16:$frame_size),
-             "save \t$$ra, $$s0, $$s1, $frame_size", [], IIStore >, MayStore {
+             "save\t$$ra, $$s0, $$s1, $frame_size", [], IIStore >, MayStore {
+  let isCodeGenOnly = 1;
+}
+
+//
+// Use Save to decrement the SP by a constant since SP is not
+// a Mips16 register.
+//
+let ra=0, s=0,s0=0,s1=0 in
+def SaveDecSpF16:
+  FI8_SVRS16<0b1, (outs), (ins uimm16:$frame_size),
+             "save\t$frame_size", [], IIStore >, MayStore {
   let isCodeGenOnly = 1;
 }
 //
diff --git a/lib/Target/Mips/Mips16RegisterInfo.cpp b/lib/Target/Mips/Mips16RegisterInfo.cpp
index 47a41d6fa8..d7397a32f0 100644
--- a/lib/Target/Mips/Mips16RegisterInfo.cpp
+++ b/lib/Target/Mips/Mips16RegisterInfo.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Mips16RegisterInfo.h"
+#include "Mips16InstrInfo.h"
 #include "Mips.h"
 #include "MipsAnalyzeImmediate.h"
 #include "MipsInstrInfo.h"
@@ -38,15 +39,28 @@
 
 using namespace llvm;
 
-Mips16RegisterInfo::Mips16RegisterInfo(const MipsSubtarget &ST)
-  : MipsRegisterInfo(ST) {}
+Mips16RegisterInfo::Mips16RegisterInfo(const MipsSubtarget &ST,
+    const Mips16InstrInfo &I)
+  : MipsRegisterInfo(ST), TII(I) {}
 
 // This function eliminate ADJCALLSTACKDOWN,
 // ADJCALLSTACKUP pseudo instructions
 void Mips16RegisterInfo::
 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
                               MachineBasicBlock::iterator I) const {
-  // Simply discard ADJCALLSTACKDOWN, ADJCALLSTACKUP instructions.
+  const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
+
+  if (!TFI->hasReservedCallFrame(MF)) {
+    int64_t Amount = I->getOperand(0).getImm();
+
+    if (I->getOpcode() == Mips::ADJCALLSTACKDOWN)
+      Amount = -Amount;
+
+    const Mips16InstrInfo *II = static_cast<const Mips16InstrInfo*>(&TII);
+
+    II->adjustStackPtr(Mips::SP, Amount, MBB, I);
+  }
+
   MBB.erase(I);
 }
 
diff --git a/lib/Target/Mips/Mips16RegisterInfo.h b/lib/Target/Mips/Mips16RegisterInfo.h
index c702a15f60..153def20d0 100644
--- a/lib/Target/Mips/Mips16RegisterInfo.h
+++ b/lib/Target/Mips/Mips16RegisterInfo.h
@@ -20,8 +20,9 @@ namespace llvm {
 class Mips16InstrInfo;
 
 class Mips16RegisterInfo : public MipsRegisterInfo {
+  const Mips16InstrInfo &TII;
 public:
-  Mips16RegisterInfo(const MipsSubtarget &Subtarget);
+  Mips16RegisterInfo(const MipsSubtarget &Subtarget, const Mips16InstrInfo &TII);
 
   void eliminateCallFramePseudoInstr(MachineFunction &MF,
                                      MachineBasicBlock &MBB,