1 files changed, 72 insertions, 0 deletions
diff --git a/lib/Target/ARM/ARMComputeBlockSize.cpp b/lib/Target/ARM/ARMComputeBlockSize.cpp
new file mode 100644
index 000000000000..64f187d17e64
--- /dev/null
+++ b/lib/Target/ARM/ARMComputeBlockSize.cpp
@@ -0,0 +1,72 @@
+//===--- ARMComputeBlockSize.cpp - Compute machine block sizes ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARM.h"
+#include "ARMBasicBlockInfo.h"
+using namespace llvm;
+
+namespace llvm {
+
+// mayOptimizeThumb2Instruction - Returns true if optimizeThumb2Instructions
+// below may shrink MI.
+static bool
+mayOptimizeThumb2Instruction(const MachineInstr *MI) {
+  switch(MI->getOpcode()) {
+    // optimizeThumb2Instructions.
+    case ARM::t2LEApcrel:
+    case ARM::t2LDRpci:
+    // optimizeThumb2Branches.
+    case ARM::t2B:
+    case ARM::t2Bcc:
+    case ARM::tBcc:
+    // optimizeThumb2JumpTables.
+    case ARM::t2BR_JT:
+      return true;
+  }
+  return false;
+}
+
+void computeBlockSize(MachineFunction *MF, MachineBasicBlock *MBB,
+                      BasicBlockInfo &BBI) {
+  const ARMBaseInstrInfo *TII =
+    static_cast<const ARMBaseInstrInfo *>(MF->getSubtarget().getInstrInfo());
+  bool isThumb = MF->getInfo<ARMFunctionInfo>()->isThumbFunction();
+  BBI.Size = 0;
+  BBI.Unalign = 0;
+  BBI.PostAlign = 0;
+
+  for (MachineInstr &I : *MBB) {
+    BBI.Size += TII->getInstSizeInBytes(I);
+    // For inline asm, getInstSizeInBytes returns a conservative estimate.
+    // The actual size may be smaller, but still a multiple of the instr size.
+    if (I.isInlineAsm())
+      BBI.Unalign = isThumb ? 1 : 2;
+    // Also consider instructions that may be shrunk later.
+    else if (isThumb && mayOptimizeThumb2Instruction(&I))
+      BBI.Unalign = 1;
+  }
+
+  // tBR_JTr contains a .align 2 directive.
+  if (!MBB->empty() && MBB->back().getOpcode() == ARM::tBR_JTr) {
+    BBI.PostAlign = 2;
+    MBB->getParent()->ensureAlignment(2);
+  }
+}
+
+std::vector<BasicBlockInfo> computeAllBlockSizes(MachineFunction *MF) {
+  std::vector<BasicBlockInfo> BBInfo;
+  BBInfo.resize(MF->getNumBlockIDs());
+
+  for (MachineBasicBlock &MBB : *MF)
+    computeBlockSize(MF, &MBB, BBInfo[MBB.getNumber()]);
+
+  return BBInfo;
+}
+
+} // end namespace