[llvm-commits] [llvm] r96634 - in /llvm/trunk: include/llvm/Target/TargetRegisterInfo.h lib/CodeGen/PrologEpilogInserter.cpp lib/Target/ARM/ARMBaseRegisterInfo.cpp lib/Target/ARM/ARMBaseRegisterInfo.h

Jim Grosbach grosbach at apple.com
Thu Feb 18 16:16:24 PST 2010


Author: grosbach
Date: Thu Feb 18 18:16:24 2010
New Revision: 96634

URL: http://llvm.org/viewvc/llvm-project?rev=96634&view=rev
Log:
Radar 7636153. In the presence of large call frames, it's not sufficient
for ARM to just check if a function has a FP to determine if it's safe
to simplify the stack adjustment pseudo ops prior to eliminating frame
indices. Allow targets to override the default behavior and does so for ARM
and Thumb2.


Modified:
    llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
    llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
    llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp
    llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h

Modified: llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetRegisterInfo.h?rev=96634&r1=96633&r2=96634&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Target/TargetRegisterInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetRegisterInfo.h Thu Feb 18 18:16:24 2010
@@ -587,6 +587,17 @@
     return !hasFP(MF);
   }
 
+  /// canSimplifyCallFramePseudos - When possible, it's best to simplify the
+  /// call frame pseudo ops before doing frame index elimination. This is
+  /// possible only when frame index references between the pseudos won't
+  /// need adjusted for the call frame adjustments. Normally, that's true
+  /// if the function has a reserved call frame or a frame pointer. Some
+  /// targets (Thumb2, for example) may have more complicated criteria,
+  /// however, and can override this behavior.
+  virtual bool canSimplifyCallFramePseudos(MachineFunction &MF) const {
+    return hasReservedCallFrame(MF) || hasFP(MF);
+  }
+
   /// hasReservedSpillSlot - Return true if target has reserved a spill slot in
   /// the stack frame of the given function for the specified register. e.g. On
   /// x86, if the frame register is required, the first fixed stack object is

Modified: llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp?rev=96634&r1=96633&r2=96634&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp (original)
+++ llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp Thu Feb 18 18:16:24 2010
@@ -175,9 +175,10 @@
     MachineBasicBlock::iterator I = *i;
 
     // If call frames are not being included as part of the stack frame, and
-    // there is no dynamic allocation (therefore referencing frame slots off
-    // sp), leave the pseudo ops alone. We'll eliminate them later.
-    if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
+    // the target doesn't indicate otherwise, remove the call frame pseudos
+    // here. The sub/add sp instruction pairs are still inserted, but we don't
+    // need to track the SP adjustment for frame index elimination.
+    if (RegInfo->canSimplifyCallFramePseudos(Fn))
       RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
   }
 }

Modified: llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp?rev=96634&r1=96633&r2=96634&view=diff

==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp Thu Feb 18 18:16:24 2010
@@ -1085,6 +1085,16 @@
   return !MF.getFrameInfo()->hasVarSizedObjects();
 }
 
+// canSimplifyCallFramePseudos - If there is a reserved call frame, the
+// call frame pseudos can be simplified. Unlike most targets, having a FP
+// is not sufficient here since we still may reference some objects via SP
+// even when FP is available in Thumb2 mode.
+bool ARMBaseRegisterInfo::
+canSimplifyCallFramePseudos(MachineFunction &MF) const {
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+  return hasReservedCallFrame(MF) || (AFI->isThumb1OnlyFunction() && hasFP(MF));
+}
+
 static void
 emitSPUpdate(bool isARM,
              MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
@@ -1149,7 +1159,6 @@
   MachineInstr &MI = *II;
   MachineBasicBlock &MBB = *MI.getParent();
   MachineFunction &MF = *MBB.getParent();
-  const MachineFrameInfo *MFI = MF.getFrameInfo();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   assert(!AFI->isThumb1OnlyFunction() &&
          "This eliminateFrameIndex does not support Thumb1!");
@@ -1160,12 +1169,12 @@
   }
 
   int FrameIndex = MI.getOperand(i).getIndex();
-  int Offset = MFI->getObjectOffset(FrameIndex) + MFI->getStackSize() + SPAdj;
   unsigned FrameReg;
 
-  Offset = getFrameIndexReference(MF, FrameIndex, FrameReg);
+  int Offset = getFrameIndexReference(MF, FrameIndex, FrameReg);
   if (FrameReg != ARM::SP)
     SPAdj = 0;
+  Offset += SPAdj;
 
   // Modify MI as necessary to handle as much of 'Offset' as possible
   bool Done = false;

Modified: llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h?rev=96634&r1=96633&r2=96634&view=diff

==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h Thu Feb 18 18:16:24 2010
@@ -138,6 +138,7 @@
   virtual bool requiresFrameIndexScavenging(const MachineFunction &MF) const;
 
   virtual bool hasReservedCallFrame(MachineFunction &MF) const;
+  virtual bool canSimplifyCallFramePseudos(MachineFunction &MF) const;
 
   virtual void eliminateCallFramePseudoInstr(MachineFunction &MF,
                                              MachineBasicBlock &MBB,





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