Restore the behavior of frame lowering before my refactoring.

It turns out that ppc backend has really weird interdependencies
over different hooks and all stuff is fragile wrt small changes.
This should fix PR8749

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122155 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCFrameInfo.cpp b/lib/Target/PowerPC/PPCFrameInfo.cpp
index 817b8f166a0ff0c930c2ac8d9914a761b144c8c4..918fb07f57b8e8075d806586665415879b47c7b5 100644 (file)
--- a/lib/Target/PowerPC/PPCFrameInfo.cpp
+++ b/lib/Target/PowerPC/PPCFrameInfo.cpp
@@ -227,6 +227,17 @@ void PPCFrameInfo::determineFrameLayout(MachineFunction &MF) const {
 // pointer register.
 bool PPCFrameInfo::hasFP(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
+  // FIXME: This is pretty much broken by design: hasFP() might be called really
+  // early, before the stack layout was calculated and thus hasFP() might return
+  // true or false here depending on the time of call.
+  return (MFI->getStackSize()) && needsFP(MF);
+}
+
+// needsFP - 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.
+bool PPCFrameInfo::needsFP(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
 
   // Naked functions have no stack frame pushed, so we don't have a frame
   // pointer.
@@ -267,6 +278,8 @@ void PPCFrameInfo::emitPrologue(MachineFunction &MF) const {
   MBBI = MBB.begin();
 
   // Work out frame sizes.
+  // FIXME: determineFrameLayout() may change the frame size. This should be
+  // moved upper, to some hook.
   determineFrameLayout(MF);
   unsigned FrameSize = MFI->getStackSize();
 
@@ -280,7 +293,7 @@ void PPCFrameInfo::emitPrologue(MachineFunction &MF) const {
   PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
   bool MustSaveLR = FI->mustSaveLR();
   // Do we have a frame pointer for this function?
-  bool HasFP = hasFP(MF) && FrameSize;
+  bool HasFP = hasFP(MF);
 
   int LROffset = PPCFrameInfo::getReturnSaveOffset(isPPC64, isDarwinABI);
 
@@ -516,7 +529,7 @@ void PPCFrameInfo::emitEpilogue(MachineFunction &MF,
   PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
   bool MustSaveLR = FI->mustSaveLR();
   // Do we have a frame pointer for this function?
-  bool HasFP = hasFP(MF) && FrameSize;
+  bool HasFP = hasFP(MF);
 
   int LROffset = PPCFrameInfo::getReturnSaveOffset(isPPC64, isDarwinABI);
 
@@ -735,7 +748,7 @@ PPCFrameInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
   MachineFrameInfo *MFI = MF.getFrameInfo();
 
   // If the frame pointer save index hasn't been defined yet.
-  if (!FPSI && hasFP(MF)) {
+  if (!FPSI && needsFP(MF)) {
     // Find out what the fix offset of the frame pointer save area.
     int FPOffset = getFramePointerSaveOffset(isPPC64, isDarwinABI);
     // Allocate the frame index for frame pointer save area.
@@ -758,7 +771,7 @@ PPCFrameInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
   //        r0 for now.
 
   if (RegInfo->requiresRegisterScavenging(MF)) // FIXME (64-bit): Enable.
-    if (hasFP(MF) || spillsCR(MF)) {
+    if (needsFP(MF) || spillsCR(MF)) {
       const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
       const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
       const TargetRegisterClass *RC = isPPC64 ? G8RC : GPRC;
@@ -779,7 +792,7 @@ void PPCFrameInfo::processFunctionBeforeFrameFinalized(MachineFunction &MF)
   const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
 
   // Early exit if no callee saved registers are modified!
-  if (CSI.empty() && !hasFP(MF)) {
+  if (CSI.empty() && !needsFP(MF)) {
     return;
   }
 
@@ -869,7 +882,7 @@ void PPCFrameInfo::processFunctionBeforeFrameFinalized(MachineFunction &MF)
 
   // Check whether the frame pointer register is allocated. If so, make sure it
   // is spilled to the correct offset.
-  if (hasFP(MF)) {
+  if (needsFP(MF)) {
     HasGPSaveArea = true;
 
     int FI = PFI->getFramePointerSaveIndex();

diff --git a/lib/Target/PowerPC/PPCFrameInfo.h b/lib/Target/PowerPC/PPCFrameInfo.h
index 204aec8a8bbd263dea11b130f6b5a4de343177f5..470963a8176d0b1d81ce34a62c16db2eaea3c213 100644 (file)
--- a/lib/Target/PowerPC/PPCFrameInfo.h
+++ b/lib/Target/PowerPC/PPCFrameInfo.h
@@ -38,6 +38,7 @@ public:
   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;
 
   bool hasFP(const MachineFunction &MF) const;
+  bool needsFP(const MachineFunction &MF) const;
   void getInitialFrameState(std::vector<MachineMove> &Moves) const;
 
   void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,

diff --git a/lib/Target/PowerPC/PPCRegisterInfo.cpp b/lib/Target/PowerPC/PPCRegisterInfo.cpp
index daef277332332c044393e6132d6e783f18cf5fcd..f931dcbdacc76cbcee569505cb45eaaf81996517 100644 (file)
--- a/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -258,7 +258,8 @@ PPCRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
 
 BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   BitVector Reserved(getNumRegs());
-  const TargetFrameInfo *TFI = MF.getTarget().getFrameInfo();
+  const PPCFrameInfo *PPCFI =
+    static_cast<const PPCFrameInfo*>(MF.getTarget().getFrameInfo());
 
   Reserved.set(PPC::R0);
   Reserved.set(PPC::R1);
@@ -305,7 +306,7 @@ BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
     }
   }
 
-  if (TFI->hasFP(MF))
+  if (PPCFI->needsFP(MF))
     Reserved.set(PPC::R31);
 
   return Reserved;

diff --git a/lib/Target/PowerPC/PPCRegisterInfo.td b/lib/Target/PowerPC/PPCRegisterInfo.td
index 2fbd41bd84a586f9915b22a96b7f3e0ae11a6ec3..879f26700c6c47196a897a3654b0566f77547a84 100644 (file)
--- a/lib/Target/PowerPC/PPCRegisterInfo.td
+++ b/lib/Target/PowerPC/PPCRegisterInfo.td
@@ -301,12 +301,13 @@ def GPRC : RegisterClass<"PPC", [i32], 32,
       // When using the 32-bit SVR4 ABI, r13 is reserved for the Small Data Area
       // pointer.
       const PPCSubtarget &Subtarget = MF.getTarget().getSubtarget<PPCSubtarget>();
-      const TargetFrameInfo *TFI = MF.getTarget().getFrameInfo();
+      const PPCFrameInfo *PPCFI =
+        static_cast<const PPCFrameInfo*>(MF.getTarget().getFrameInfo());
    
       if (Subtarget.isPPC64() || Subtarget.isSVR4ABI())
         return end()-5;  // don't allocate R13, R31, R0, R1, LR
         
-      if (TFI->hasFP(MF))
+      if (PPCFI->needsFP(MF))
         return end()-4;  // don't allocate R31, R0, R1, LR
       else
         return end()-3;  // don't allocate R0, R1, LR
@@ -331,8 +332,9 @@ def G8RC : RegisterClass<"PPC", [i64], 64,
     }
     G8RCClass::iterator
     G8RCClass::allocation_order_end(const MachineFunction &MF) const {
-      const TargetFrameInfo *TFI = MF.getTarget().getFrameInfo();
-      if (TFI->hasFP(MF))
+      const PPCFrameInfo *PPCFI =
+        static_cast<const PPCFrameInfo*>(MF.getTarget().getFrameInfo());
+      if (PPCFI->needsFP(MF))
         return end()-5;
       else
         return end()-4;

diff --git a/test/CodeGen/PowerPC/2010-12-18-PPCStackRefs.ll b/test/CodeGen/PowerPC/2010-12-18-PPCStackRefs.ll
new file mode 100644 (file)
index 0000000..bf3d577
--- /dev/null
+++ b/test/CodeGen/PowerPC/2010-12-18-PPCStackRefs.ll
@@ -0,0 +1,22 @@
+; RUN: llc -disable-fp-elim < %s | FileCheck %s
+; PR8749
+target datalayout = "E-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f128:64:128-n32"
+target triple = "powerpc-apple-darwin9.8"
+
+define i32 @main() nounwind {
+entry:
+; Make sure we're generating references using the red zone
+; CHECK: main:
+; CHECK: stw r3, -12(r1)
+  %retval = alloca i32
+  %0 = alloca i32
+  %"alloca point" = bitcast i32 0 to i32
+  store i32 0, i32* %0, align 4
+  %1 = load i32* %0, align 4
+  store i32 %1, i32* %retval, align 4
+  br label %return
+
+return:                                           ; preds = %entry
+  %retval1 = load i32* %retval
+  ret i32 %retval1
+}