Factor the stack alignment calculations out into a target independent pass.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90336 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineFrameInfo.h

@@ -327,7 +327,20 @@ public:
   /// setMaxAlignment - Set the preferred alignment.
   ///
   void setMaxAlignment(unsigned Align) { MaxAlignment = Align; }
-  
+
+  /// calculateMaxStackAlignment() - If there is a local object which requires
+  /// greater alignment than the current max alignment, adjust accordingly.
+  void calculateMaxStackAlignment() {
+    for (int i = getObjectIndexBegin(),
+         e = getObjectIndexEnd(); i != e; ++i) {
+      if (isDeadObjectIndex(i))
+        continue;
+
+      unsigned Align = getObjectAlignment(i);
+      MaxAlignment = std::max(MaxAlignment, Align);
+    }
+  }
+
   /// hasCalls - Return true if the current function has no function calls.
   /// This is only valid during or after prolog/epilog code emission.
   ///

include/llvm/CodeGen/Passes.h

@@ -191,6 +191,10 @@ namespace llvm {
   /// the GCC-style builtin setjmp/longjmp (sjlj) to handling EH control flow.
   FunctionPass *createSjLjEHPass(const TargetLowering *tli);
 
+  /// createMaxStackAlignmentCalculatorPass() - Determine the maximum required
+  /// alignment for a function.
+  FunctionPass* createMaxStackAlignmentCalculatorPass();
+
 } // End llvm namespace
 
 #endif

lib/CodeGen/MaxStackAlignment.cpp

@@ -0,0 +1,70 @@
+//===-- MaxStackAlignment.cpp - Compute the required stack alignment -- ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass looks for vector register usage and aligned local objects to
+// calculate the maximum required alignment for a function. This is used by
+// targets which support it to determine if dynamic stack realignment is
+// necessary.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+
+using namespace llvm;
+
+namespace {
+  struct MaximalStackAlignmentCalculator : public MachineFunctionPass {
+    static char ID;
+    MaximalStackAlignmentCalculator() : MachineFunctionPass(&ID) {}
+
+    virtual bool runOnMachineFunction(MachineFunction &MF) {
+      MachineFrameInfo *FFI = MF.getFrameInfo();
+      MachineRegisterInfo &RI = MF.getRegInfo();
+
+      // Calculate max stack alignment of all already allocated stack objects.
+      FFI->calculateMaxStackAlignment();
+      unsigned MaxAlign = FFI->getMaxAlignment();
+
+      // Be over-conservative: scan over all vreg defs and find whether vector
+      // registers are used. If yes, there is probability that vector registers
+      // will be spilled and thus the stack needs to be aligned properly.
+      // FIXME: It would be better to only do this if a spill actually
+      // happens rather than conseratively aligning the stack regardless.
+      for (unsigned RegNum = TargetRegisterInfo::FirstVirtualRegister;
+           RegNum < RI.getLastVirtReg(); ++RegNum)
+        MaxAlign = std::max(MaxAlign, RI.getRegClass(RegNum)->getAlignment());
+
+      if (FFI->getMaxAlignment() == MaxAlign)
+        return false;
+
+      FFI->setMaxAlignment(MaxAlign);
+      return true;
+    }
+
+    virtual const char *getPassName() const {
+      return "Stack Alignment Requirements Auto-Detector";
+    }
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+  };
+
+  char MaximalStackAlignmentCalculator::ID = 0;
+}
+
+FunctionPass*
+llvm::createMaxStackAlignmentCalculatorPass() {
+  return new MaximalStackAlignmentCalculator();
+}
+

lib/Target/ARM/ARM.h

@@ -109,7 +109,6 @@ FunctionPass *createNEONPreAllocPass();
 FunctionPass *createNEONMoveFixPass();
 FunctionPass *createThumb2ITBlockPass();
 FunctionPass *createThumb2SizeReductionPass();
-FunctionPass *createARMMaxStackAlignmentCalculatorPass();
 
 extern Target TheARMTarget, TheThumbTarget;
 

lib/Target/ARM/ARMBaseRegisterInfo.cpp

@@ -471,21 +471,6 @@ ARMBaseRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
   }
 }
 
-static unsigned calculateMaxStackAlignment(const MachineFrameInfo *FFI) {
-  unsigned MaxAlign = 0;
-
-  for (int i = FFI->getObjectIndexBegin(),
-         e = FFI->getObjectIndexEnd(); i != e; ++i) {
-    if (FFI->isDeadObjectIndex(i))
-      continue;
-
-    unsigned Align = FFI->getObjectAlignment(i);
-    MaxAlign = std::max(MaxAlign, Align);
-  }
-
-  return MaxAlign;
-}
-
 /// hasFP - Return true if the specified function should have a dedicated frame
 /// pointer register.  This is true if the function has variable sized allocas
 /// or if frame pointer elimination is disabled.
@@ -585,14 +570,12 @@ ARMBaseRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
   SmallVector<unsigned, 4> UnspilledCS2GPRs;
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
 
-  MachineFrameInfo *MFI = MF.getFrameInfo();
 
   // Calculate and set max stack object alignment early, so we can decide
   // whether we will need stack realignment (and thus FP).
   if (RealignStack) {
-    unsigned MaxAlign = std::max(MFI->getMaxAlignment(),
-                                 calculateMaxStackAlignment(MFI));
-    MFI->setMaxAlignment(MaxAlign);
+    MachineFrameInfo *MFI = MF.getFrameInfo();
+    MFI->calculateMaxStackAlignment();
   }
 
   // Don't spill FP if the frame can be eliminated. This is determined
@@ -1479,48 +1462,4 @@ emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const {
     emitSPUpdate(isARM, MBB, MBBI, dl, TII, VARegSaveSize);
 }
 
-namespace {
-  struct MaximalStackAlignmentCalculator : public MachineFunctionPass {
-    static char ID;
-    MaximalStackAlignmentCalculator() : MachineFunctionPass(&ID) {}
-
-    virtual bool runOnMachineFunction(MachineFunction &MF) {
-      MachineFrameInfo *FFI = MF.getFrameInfo();
-      MachineRegisterInfo &RI = MF.getRegInfo();
-
-      // Calculate max stack alignment of all already allocated stack objects.
-      unsigned MaxAlign = calculateMaxStackAlignment(FFI);
-
-      // Be over-conservative: scan over all vreg defs and find, whether vector
-      // registers are used. If yes - there is probability, that vector register
-      // will be spilled and thus stack needs to be aligned properly.
-      for (unsigned RegNum = TargetRegisterInfo::FirstVirtualRegister;
-           RegNum < RI.getLastVirtReg(); ++RegNum)
-        MaxAlign = std::max(MaxAlign, RI.getRegClass(RegNum)->getAlignment());
-
-      if (FFI->getMaxAlignment() == MaxAlign)
-        return false;
-
-      FFI->setMaxAlignment(MaxAlign);
-      return true;
-    }
-
-    virtual const char *getPassName() const {
-      return "ARM Stack Required Alignment Auto-Detector";
-    }
-
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.setPreservesCFG();
-      MachineFunctionPass::getAnalysisUsage(AU);
-    }
-  };
-
-  char MaximalStackAlignmentCalculator::ID = 0;
-}
-
-FunctionPass*
-llvm::createARMMaxStackAlignmentCalculatorPass() {
-  return new MaximalStackAlignmentCalculator();
-}
-
 #include "ARMGenRegisterInfo.inc"

lib/Target/ARM/ARMTargetMachine.cpp

@@ -95,7 +95,7 @@ bool ARMBaseTargetMachine::addPreRegAlloc(PassManagerBase &PM,
 
   // Calculate and set max stack object alignment early, so we can decide
   // whether we will need stack realignment (and thus FP).
-  PM.add(createARMMaxStackAlignmentCalculatorPass());
+  PM.add(createMaxStackAlignmentCalculatorPass());
 
   // FIXME: temporarily disabling load / store optimization pass for Thumb1.
   if (OptLevel != CodeGenOpt::None && !Subtarget.isThumb1Only())

lib/Target/X86/X86.h

@@ -62,11 +62,6 @@ MCCodeEmitter *createX86MCCodeEmitter(const Target &, TargetMachine &TM);
 ///
 FunctionPass *createEmitX86CodeToMemory();
 
-/// createX86MaxStackAlignmentCalculatorPass - This function returns a pass
-/// which calculates maximal stack alignment required for function
-///
-FunctionPass *createX86MaxStackAlignmentCalculatorPass();
-
 extern Target TheX86_32Target, TheX86_64Target;
 
 } // End llvm namespace

lib/Target/X86/X86RegisterInfo.cpp

@@ -423,21 +423,6 @@ BitVector X86RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
 // Stack Frame Processing methods
 //===----------------------------------------------------------------------===//
 
-static unsigned calculateMaxStackAlignment(const MachineFrameInfo *FFI) {
-  unsigned MaxAlign = 0;
-
-  for (int i = FFI->getObjectIndexBegin(),
-         e = FFI->getObjectIndexEnd(); i != e; ++i) {
-    if (FFI->isDeadObjectIndex(i))
-      continue;
-
-    unsigned Align = FFI->getObjectAlignment(i);
-    MaxAlign = std::max(MaxAlign, Align);
-  }
-
-  return MaxAlign;
-}
-
 /// hasFP - Return true if the specified function should have a dedicated frame
 /// pointer register.  This is true if the function has variable sized allocas
 /// or if frame pointer elimination is disabled.
@@ -638,10 +623,7 @@ X86RegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
 
   // Calculate and set max stack object alignment early, so we can decide
   // whether we will need stack realignment (and thus FP).
-  unsigned MaxAlign = std::max(MFI->getMaxAlignment(),
-                               calculateMaxStackAlignment(MFI));
-
-  MFI->setMaxAlignment(MaxAlign);
+  MFI->calculateMaxStackAlignment();
 
   X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
   int32_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
@@ -1482,45 +1464,3 @@ unsigned getX86SubSuperRegister(unsigned Reg, EVT VT, bool High) {
 }
 
 #include "X86GenRegisterInfo.inc"
-
-namespace {
-  struct MSAC : public MachineFunctionPass {
-    static char ID;
-    MSAC() : MachineFunctionPass(&ID) {}
-
-    virtual bool runOnMachineFunction(MachineFunction &MF) {
-      MachineFrameInfo *FFI = MF.getFrameInfo();
-      MachineRegisterInfo &RI = MF.getRegInfo();
-
-      // Calculate max stack alignment of all already allocated stack objects.
-      unsigned MaxAlign = calculateMaxStackAlignment(FFI);
-
-      // Be over-conservative: scan over all vreg defs and find, whether vector
-      // registers are used. If yes - there is probability, that vector register
-      // will be spilled and thus stack needs to be aligned properly.
-      for (unsigned RegNum = TargetRegisterInfo::FirstVirtualRegister;
-           RegNum < RI.getLastVirtReg(); ++RegNum)
-        MaxAlign = std::max(MaxAlign, RI.getRegClass(RegNum)->getAlignment());
-
-      if (FFI->getMaxAlignment() == MaxAlign)
-        return false;
-
-      FFI->setMaxAlignment(MaxAlign);
-      return true;
-    }
-
-    virtual const char *getPassName() const {
-      return "X86 Maximal Stack Alignment Calculator";
-    }
-
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.setPreservesCFG();
-      MachineFunctionPass::getAnalysisUsage(AU);
-    }
-  };
-
-  char MSAC::ID = 0;
-}
-
-FunctionPass*
-llvm::createX86MaxStackAlignmentCalculatorPass() { return new MSAC(); }

lib/Target/X86/X86TargetMachine.cpp

@@ -163,7 +163,7 @@ bool X86TargetMachine::addPreRegAlloc(PassManagerBase &PM,
                                       CodeGenOpt::Level OptLevel) {
   // Calculate and set max stack object alignment early, so we can decide
   // whether we will need stack realignment (and thus FP).
-  PM.add(createX86MaxStackAlignmentCalculatorPass());
+  PM.add(createMaxStackAlignmentCalculatorPass());
   return false;  // -print-machineinstr shouldn't print after this.
 }