Imported Upstream version 5.18.0.225

Former-commit-id: 10196d987d5fc5564b9d3b33b1fdf13190f4d0b5

external/llvm/lib/Target/AMDGPU/AMDGPUFrameLowering.cpp

@@ -0,0 +1,66 @@
+//===----------------------- 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 AMDGPU target machine.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AMDGPUFrameLowering.h"
+
+using namespace llvm;
+AMDGPUFrameLowering::AMDGPUFrameLowering(StackDirection D, unsigned StackAl,
+    int LAO, unsigned TransAl)
+  : TargetFrameLowering(D, StackAl, LAO, TransAl) { }
+
+AMDGPUFrameLowering::~AMDGPUFrameLowering() = default;
+
+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;
+}