R600: Support for indirect addressing v4

Only implemented for R600 so far.  SI is missing implementations of a
few callbacks used by the Indirect Addressing pass and needs code to
handle frame indices.

At the moment R600 only supports array sizes of 16 dwords or less.
Register packing of vector types is currently disabled, which means that a
vec4 is stored in T0_X, T1_X, T2_X, T3_X, rather than T0_XYZW. In order
to correctly pack registers in all cases, we will need to implement an
analysis pass for R600 that determines the correct vector width for each
array.

v2:
  - Add support for i8 zext load from stack.
  - Coding style fixes

v3:
  - Don't reserve registers for indirect addressing when it isn't
    being used.
  - Fix bug caused by LLVM limiting the number of SubRegIndex
    declarations.

v4:
  - Fix 64-bit defines

llvm-svn: 174525

1 files changed, 122 insertions, 0 deletions

diff --git a/llvm/lib/Target/R600/AMDGPUFrameLowering.cpp b/llvm/lib/Target/R600/AMDGPUFrameLowering.cpp
new file mode 100644
index 00000000000..815d6f71c3b
--- /dev/null
+++ b/llvm/lib/Target/R600/AMDGPUFrameLowering.cpp
@@ -0,0 +1,122 @@
+//===----------------------- AMDGPUFrameLowering.cpp ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//==-----------------------------------------------------------------------===//
+//
+// Interface to describe a layout of a stack frame on a AMDIL target machine
+//
+//===----------------------------------------------------------------------===//
+#include "AMDGPUFrameLowering.h"
+#include "AMDGPURegisterInfo.h"
+#include "R600MachineFunctionInfo.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/IR/Instructions.h"
+
+using namespace llvm;
+AMDGPUFrameLowering::AMDGPUFrameLowering(StackDirection D, unsigned StackAl,
+    int LAO, unsigned TransAl)
+  : TargetFrameLowering(D, StackAl, LAO, TransAl) { }
+
+AMDGPUFrameLowering::~AMDGPUFrameLowering() { }
+
+unsigned AMDGPUFrameLowering::getStackWidth(const MachineFunction &MF) const {
+
+  // XXX: Hardcoding to 1 for now.
+  //
+  // I think the StackWidth should stored as metadata associated with the
+  // MachineFunction.  This metadata can either be added by a frontend, or
+  // calculated by a R600 specific LLVM IR pass.
+  //
+  // The StackWidth determines how stack objects are laid out in memory.
+  // For a vector stack variable, like: int4 stack[2], the data will be stored
+  // in the following ways depending on the StackWidth.
+  //
+  // StackWidth = 1:
+  //
+  // T0.X = stack[0].x
+  // T1.X = stack[0].y
+  // T2.X = stack[0].z
+  // T3.X = stack[0].w
+  // T4.X = stack[1].x
+  // T5.X = stack[1].y
+  // T6.X = stack[1].z
+  // T7.X = stack[1].w
+  //
+  // StackWidth = 2:
+  //
+  // T0.X = stack[0].x
+  // T0.Y = stack[0].y
+  // T1.X = stack[0].z
+  // T1.Y = stack[0].w
+  // T2.X = stack[1].x
+  // T2.Y = stack[1].y
+  // T3.X = stack[1].z
+  // T3.Y = stack[1].w
+  // 
+  // StackWidth = 4:
+  // T0.X = stack[0].x
+  // T0.Y = stack[0].y
+  // T0.Z = stack[0].z
+  // T0.W = stack[0].w
+  // T1.X = stack[1].x
+  // T1.Y = stack[1].y
+  // T1.Z = stack[1].z
+  // T1.W = stack[1].w
+  return 1;
+}
+
+/// \returns The number of registers allocated for \p FI.
+int AMDGPUFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
+                                         int FI) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  unsigned Offset = 0;
+  int UpperBound = FI == -1 ? MFI->getNumObjects() : FI;
+
+  for (int i = MFI->getObjectIndexBegin(); i < UpperBound; ++i) {
+    const AllocaInst *Alloca = MFI->getObjectAllocation(i);
+    unsigned ArrayElements;
+    const Type *AllocaType = Alloca->getAllocatedType();
+    const Type *ElementType;
+
+    if (AllocaType->isArrayTy()) {
+      ArrayElements = AllocaType->getArrayNumElements();
+      ElementType = AllocaType->getArrayElementType();
+    } else {
+      ArrayElements = 1;
+      ElementType = AllocaType;
+    }
+
+    unsigned VectorElements;
+    if (ElementType->isVectorTy()) {
+      VectorElements = ElementType->getVectorNumElements();
+    } else {
+      VectorElements = 1;
+    }
+
+    Offset += (VectorElements / getStackWidth(MF)) * ArrayElements;
+  }
+  return Offset;
+}
+
+const TargetFrameLowering::SpillSlot *
+AMDGPUFrameLowering::getCalleeSavedSpillSlots(unsigned &NumEntries) const {
+  NumEntries = 0;
+  return 0;
+}
+void
+AMDGPUFrameLowering::emitPrologue(MachineFunction &MF) const {
+}
+void
+AMDGPUFrameLowering::emitEpilogue(MachineFunction &MF,
+                                  MachineBasicBlock &MBB) const {
+}
+
+bool
+AMDGPUFrameLowering::hasFP(const MachineFunction &MF) const {
+  return false;
+}