Add a thumb2 pass to insert IT blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75218 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/Thumb2ITBlockPass.cpp b/lib/Target/ARM/Thumb2ITBlockPass.cpp
new file mode 100644
index 0000000..f6f75a1
--- /dev/null
+++ b/lib/Target/ARM/Thumb2ITBlockPass.cpp
@@ -0,0 +1,108 @@
+//===-- Thumb2ITBlockPass.cpp - Insert Thumb IT blocks -----------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "thumb2-it"
+#include "ARM.h"
+#include "ARMInstrInfo.h"
+#include "ARMMachineFunctionInfo.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/Statistic.h"
+using namespace llvm;
+
+STATISTIC(NumITs, "Number of IT blocks inserted");
+
+namespace {
+ struct VISIBILITY_HIDDEN Thumb2ITBlockPass : public MachineFunctionPass {
+ static char ID;
+ Thumb2ITBlockPass() : MachineFunctionPass(&ID) {}
+
+ const ARMBaseInstrInfo *TII;
+ ARMFunctionInfo *AFI;
+
+ virtual bool runOnMachineFunction(MachineFunction &Fn);
+
+ virtual const char *getPassName() const {
+ return "Thumb IT blocks insertion pass";
+ }
+
+ private:
+ bool InsertITBlocks(MachineBasicBlock &MBB);
+ };
+ char Thumb2ITBlockPass::ID = 0;
+}
+
+bool Thumb2ITBlockPass::InsertITBlocks(MachineBasicBlock &MBB) {
+ bool Modified = false;
+
+ MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
+ while (MBBI != E) {
+ MachineInstr *MI = &*MBBI;
+ ARMCC::CondCodes CC = TII->getPredicate(MI);
+ if (CC == ARMCC::AL) {
+ ++MBBI;
+ continue;
+ }
+
+ // Insert an IT instruction.
+ DebugLoc dl = MI->getDebugLoc();
+ MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII->get(ARM::t2IT))
+ .addImm(CC);
+ ++MBBI;
+
+ // Finalize IT mask. If the following instruction is not predicated or it's
+ // predicated on a condition that's not the same or the opposite of CC, then
+ // the mask is 0x8.
+ ARMCC::CondCodes OCC = ARMCC::getOppositeCondition(CC);
+ unsigned Mask = 0x8;
+ while (MBBI != E || (Mask & 1)) {
+ ARMCC::CondCodes NCC = TII->getPredicate(&*MBBI);
+ if (NCC == CC) {
+ Mask >>= 1;
+ Mask |= 0x8;
+ } else if (NCC == OCC) {
+ Mask >>= 1;
+ } else {
+ break;
+ }
+ ++MBBI;
+ }
+ MIB.addImm(Mask);
+ Modified = true;
+ ++NumITs;
+ }
+
+ return Modified;
+}
+
+bool Thumb2ITBlockPass::runOnMachineFunction(MachineFunction &Fn) {
+ const TargetMachine &TM = Fn.getTarget();
+ AFI = Fn.getInfo<ARMFunctionInfo>();
+ TII = static_cast<const ARMBaseInstrInfo*>(TM.getInstrInfo());
+
+ if (!AFI->isThumbFunction())
+ return false;
+
+ bool Modified = false;
+ for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
+ ++MFI) {
+ MachineBasicBlock &MBB = *MFI;
+ Modified |= InsertITBlocks(MBB);
+ }
+
+ return Modified;
+}
+
+/// createThumb2ITBlockPass - returns and instance of the Thumb IT blocks
+/// insertion pass.
+FunctionPass *llvm::createThumb2ITBlockPass() {
+ return new Thumb2ITBlockPass();
+}