PR15868 fix.

Introduction:
In case when stack alignment is 8 and GPRs parameter part size is not N*8:
we add padding to GPRs part, so part's last byte must be recovered at
address K*8-1.
We need to do it, since remained (stack) part of parameter starts from
address K*8, and we need to "attach" "GPRs head" without gaps to it:

Stack:
|---- 8 bytes block ----| |---- 8 bytes block ----| |---- 8 bytes...
[ [padding] [GPRs head] ] [ ------ Tail passed via stack  ------ ...

FIX:
Note, once we added padding we need to correct *all* Arg offsets that are going
after padded one. That's why we need this fix: Arg offsets were never corrected
before this patch. See new test-cases included in patch.

We also don't need to insert padding for byval parameters that are stored in GPRs
only. We need pad only last byval parameter and only in case it outsides GPRs
and stack alignment = 8.
Though, stack area, allocated for recovered byval params, must satisfy
"Size mod 8 = 0" restriction.

This patch reduces stack usage for some cases:
We can reduce ArgRegsSaveArea since inner N*4 bytes sized byval params my be
"packed" with alignment 4 in some cases.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182237 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 69 insertions, 11 deletions

diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index 483802b..c8637be 100644
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -141,7 +141,8 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF) const {
   assert(!AFI->isThumb1OnlyFunction() &&
          "This emitPrologue does not support Thumb1!");
   bool isARM = !AFI->isThumbFunction();
-  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
+  unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
+  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(Align);
   unsigned NumBytes = MFI->getStackSize();
   const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
   DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
@@ -357,7 +358,8 @@ void ARMFrameLowering::emitEpilogue(MachineFunction &MF,
          "This emitEpilogue does not support Thumb1!");
   bool isARM = !AFI->isThumbFunction();
 
-  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
+  unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
+  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(Align);
   int NumBytes = (int)MFI->getStackSize();
   unsigned FramePtr = RegInfo->getFrameRegister(MF);
 
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index c9ee5fb..a1443d1 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -2630,6 +2630,7 @@ ARMTargetLowering::GetF64FormalArgument(CCValAssign &VA, CCValAssign &NextVA,
 void
 ARMTargetLowering::computeRegArea(CCState &CCInfo, MachineFunction &MF,
                                   unsigned InRegsParamRecordIdx,
+                                  unsigned ArgSize,
                                   unsigned &ArgRegsSize,
                                   unsigned &ArgRegsSaveSize)
   const {
@@ -2648,7 +2649,29 @@ ARMTargetLowering::computeRegArea(CCState &CCInfo, MachineFunction &MF,
 
   unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
   ArgRegsSize = NumGPRs * 4;
-  ArgRegsSaveSize = (ArgRegsSize + Align - 1) & ~(Align - 1);
+
+  // If parameter is split between stack and GPRs...
+  if (NumGPRs && Align == 8 &&
+      (ArgRegsSize < ArgSize ||
+        InRegsParamRecordIdx >= CCInfo.getInRegsParamsCount())) {
+    // Add padding for part of param recovered from GPRs, so
+    // its last byte must be at address K*8 - 1.
+    // We need to do it, since remained (stack) part of parameter has
+    // stack alignment, and we need to "attach" "GPRs head" without gaps
+    // to it:
+    // Stack:
+    // |---- 8 bytes block ----| |---- 8 bytes block ----| |---- 8 bytes...
+    // [ [padding] [GPRs head] ] [        Tail passed via stack       ....
+    //
+    ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+    unsigned Padding =
+        ((ArgRegsSize + AFI->getArgRegsSaveSize() + Align - 1) & ~(Align-1)) -
+        (ArgRegsSize + AFI->getArgRegsSaveSize());
+    ArgRegsSaveSize = ArgRegsSize + Padding;
+  } else
+    // We don't need to extend regs save size for byval parameters if they
+    // are passed via GPRs only.
+    ArgRegsSaveSize = ArgRegsSize;
 }
 
 // The remaining GPRs hold either the beginning of variable-argument
@@ -2666,6 +2689,7 @@ ARMTargetLowering::StoreByValRegs(CCState &CCInfo, SelectionDAG &DAG,
                                   unsigned InRegsParamRecordIdx,
                                   unsigned OffsetFromOrigArg,
                                   unsigned ArgOffset,
+                                  unsigned ArgSize,
                                   bool ForceMutable) const {
 
   // Currently, two use-cases possible:
@@ -2695,7 +2719,8 @@ ARMTargetLowering::StoreByValRegs(CCState &CCInfo, SelectionDAG &DAG,
   }
 
   unsigned ArgRegsSize, ArgRegsSaveSize;
-  computeRegArea(CCInfo, MF, InRegsParamRecordIdx, ArgRegsSize, ArgRegsSaveSize);
+  computeRegArea(CCInfo, MF, InRegsParamRecordIdx, ArgSize,
+                 ArgRegsSize, ArgRegsSaveSize);
 
   // Store any by-val regs to their spots on the stack so that they may be
   // loaded by deferencing the result of formal parameter pointer or va_next.
@@ -2703,9 +2728,17 @@ ARMTargetLowering::StoreByValRegs(CCState &CCInfo, SelectionDAG &DAG,
   // was initialized, it can't be initialized again.
   if (ArgRegsSaveSize) {
 
+    unsigned Padding = ArgRegsSaveSize - ArgRegsSize;
+
+    if (Padding) {
+      assert(AFI->getStoredByValParamsPadding() == 0 &&
+             "The only parameter may be padded.");
+      AFI->setStoredByValParamsPadding(Padding);
+    }
+
     int FrameIndex = MFI->CreateFixedObject(
                       ArgRegsSaveSize,
-                      ArgOffset + ArgRegsSaveSize - ArgRegsSize,
+                      Padding + ArgOffset,
                       false);
     SDValue FIN = DAG.getFrameIndex(FrameIndex, getPointerTy());
 
@@ -2737,7 +2770,8 @@ ARMTargetLowering::StoreByValRegs(CCState &CCInfo, SelectionDAG &DAG,
     return FrameIndex;
   } else
     // This will point to the next argument passed via stack.
-    return MFI->CreateFixedObject(4, ArgOffset, !ForceMutable);
+    return MFI->CreateFixedObject(
+        4, AFI->getStoredByValParamsPadding() + ArgOffset, !ForceMutable);
 }
 
 // Setup stack frame, the va_list pointer will start from.
@@ -2756,7 +2790,7 @@ ARMTargetLowering::VarArgStyleRegisters(CCState &CCInfo, SelectionDAG &DAG,
   // argument passed via stack.
   int FrameIndex =
     StoreByValRegs(CCInfo, DAG, dl, Chain, 0, CCInfo.getInRegsParamsCount(),
-                   0, ArgOffset, ForceMutable);
+                   0, ArgOffset, 0, ForceMutable);
 
   AFI->setVarArgsFrameIndex(FrameIndex);
 }
@@ -2896,12 +2930,15 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
                 CurByValIndex,
                 Ins[VA.getValNo()].PartOffset,
                 VA.getLocMemOffset(),
+                Flags.getByValSize(),
                 true /*force mutable frames*/);
             InVals.push_back(DAG.getFrameIndex(FrameIndex, getPointerTy()));
             CCInfo.nextInRegsParam();
           } else {
+            unsigned FIOffset = VA.getLocMemOffset() +
+                                AFI->getStoredByValParamsPadding();
             int FI = MFI->CreateFixedObject(VA.getLocVT().getSizeInBits()/8,
-                                            VA.getLocMemOffset(), true);
+                                            FIOffset, true);
 
             // Create load nodes to retrieve arguments from the stack.
             SDValue FIN = DAG.getFrameIndex(FI, getPointerTy());
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 1d1b42a..8aa926f 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -480,6 +480,7 @@ namespace llvm {
                        unsigned InRegsParamRecordIdx,
                        unsigned OffsetFromOrigArg,
                        unsigned ArgOffset,
+                       unsigned ArgSize,
                        bool ForceMutable) const;
 
     void VarArgStyleRegisters(CCState &CCInfo, SelectionDAG &DAG,
@@ -489,6 +490,7 @@ namespace llvm {
 
     void computeRegArea(CCState &CCInfo, MachineFunction &MF,
                         unsigned InRegsParamRecordIdx,
+                        unsigned ArgSize,
                         unsigned &ArgRegsSize,
                         unsigned &ArgRegsSaveSize) const;
 
diff --git a/lib/Target/ARM/ARMMachineFunctionInfo.h b/lib/Target/ARM/ARMMachineFunctionInfo.h
index f4248fc..d9ec4fd 100644
--- a/lib/Target/ARM/ARMMachineFunctionInfo.h
+++ b/lib/Target/ARM/ARMMachineFunctionInfo.h
@@ -36,6 +36,13 @@ class ARMFunctionInfo : public MachineFunctionInfo {
   /// 'isThumb'.
   bool hasThumb2;
 
+  /// StByValParamsPadding - For parameter that is split between
+  /// GPRs and memory; while recovering GPRs part, when
+  /// StackAlignment == 8, and GPRs-part-size mod 8 != 0,
+  /// we need to insert gap before parameter start address. It allows to
+  /// "attach" GPR-part to the part that was passed via stack.
+  unsigned StByValParamsPadding;
+
   /// VarArgsRegSaveSize - Size of the register save area for vararg functions.
   ///
   unsigned ArgRegsSaveSize;
@@ -129,6 +136,7 @@ public:
   explicit ARMFunctionInfo(MachineFunction &MF) :
     isThumb(MF.getTarget().getSubtarget<ARMSubtarget>().isThumb()),
     hasThumb2(MF.getTarget().getSubtarget<ARMSubtarget>().hasThumb2()),
+    StByValParamsPadding(0),
     ArgRegsSaveSize(0), HasStackFrame(false), RestoreSPFromFP(false),
     LRSpilledForFarJump(false),
     FramePtrSpillOffset(0), GPRCS1Offset(0), GPRCS2Offset(0), DPRCSOffset(0),
@@ -141,7 +149,14 @@ public:
   bool isThumb1OnlyFunction() const { return isThumb && !hasThumb2; }
   bool isThumb2Function() const { return isThumb && hasThumb2; }
 
-  unsigned getArgRegsSaveSize() const { return ArgRegsSaveSize; }
+  unsigned getStoredByValParamsPadding() const { return StByValParamsPadding; }
+  void setStoredByValParamsPadding(unsigned p) { StByValParamsPadding = p; }
+
+  unsigned getArgRegsSaveSize(unsigned Align = 0) const {
+    if (!Align)
+      return ArgRegsSaveSize;
+    return (ArgRegsSaveSize + Align - 1) & ~(Align - 1);
+  }
   void setArgRegsSaveSize(unsigned s) { ArgRegsSaveSize = s; }
 
   bool hasStackFrame() const { return HasStackFrame; }
diff --git a/lib/Target/ARM/Thumb1FrameLowering.cpp b/lib/Target/ARM/Thumb1FrameLowering.cpp
index 1e2a8b0..db49db8 100644
--- a/lib/Target/ARM/Thumb1FrameLowering.cpp
+++ b/lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -88,7 +88,8 @@ void Thumb1FrameLowering::emitPrologue(MachineFunction &MF) const {
   const Thumb1InstrInfo &TII =
     *static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());
 
-  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
+  unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
+  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(Align);
   unsigned NumBytes = MFI->getStackSize();
   const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
   DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
@@ -249,7 +250,8 @@ void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
   const Thumb1InstrInfo &TII =
     *static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());
 
-  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize();
+  unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
+  unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(Align);
   int NumBytes = (int)MFI->getStackSize();
   const uint16_t *CSRegs = RegInfo->getCalleeSavedRegs();
   unsigned FramePtr = RegInfo->getFrameRegister(MF);