[ARM] Add the non-MVE instructions in Arm v8.1-M.

This adds support for the new family of conditional selection /
increment / negation instructions; the low-overhead branch
instructions (e.g. BF, WLS, DLS); the CLRM instruction to zero a whole
list of registers at once; the new VMRS/VMSR and VLDR/VSTR
instructions to get data in and out of 8.1-M system registers,
particularly including the new VPR register used by MVE vector
predication.

To support this, we also add a register name 'zr' (used by the CSEL
family to force one of the inputs to the constant 0), and operand
types for lists of registers that are also allowed to include APSR or
VPR (used by CLRM). The VLDR/VSTR instructions also need some new
addressing modes.

The low-overhead branch instructions exist in their own separate
architecture extension, which we treat as enabled by default, but you
can say -mattr=-lob or equivalent to turn it off.

Reviewers: dmgreen, samparker, SjoerdMeijer, t.p.northover

Reviewed By: samparker

Subscribers: miyuki, javed.absar, kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62667

llvm-svn: 362953

1 files changed, 67 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index 6bede80adaa..c00ded6e96a 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -762,6 +762,14 @@ void ARMAsmPrinter::emitAttributes() {
 
 //===----------------------------------------------------------------------===//
 
+static MCSymbol *getBFLabel(StringRef Prefix, unsigned FunctionNumber,
+                             unsigned LabelId, MCContext &Ctx) {
+
+  MCSymbol *Label = Ctx.getOrCreateSymbol(Twine(Prefix)
+                       + "BF" + Twine(FunctionNumber) + "_" + Twine(LabelId));
+  return Label;
+}
+
 static MCSymbol *getPICLabel(StringRef Prefix, unsigned FunctionNumber,
                              unsigned LabelId, MCContext &Ctx) {
 
@@ -1436,6 +1444,65 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     EmitToStreamer(*OutStreamer, TmpInst);
     return;
   }
+  case ARM::t2BFi:
+  case ARM::t2BFic:
+  case ARM::t2BFLi:
+  case ARM::t2BFr:
+  case ARM::t2BFLr: {
+    // This is a Branch Future instruction.
+
+    const MCExpr *BranchLabel = MCSymbolRefExpr::create(
+        getBFLabel(DL.getPrivateGlobalPrefix(), getFunctionNumber(),
+                   MI->getOperand(0).getIndex(), OutContext),
+        OutContext);
+
+    auto MCInst = MCInstBuilder(Opc).addExpr(BranchLabel);
+    if (MI->getOperand(1).isReg()) {
+      // For BFr/BFLr
+      MCInst.addReg(MI->getOperand(1).getReg());
+    } else {
+      // For BFi/BFLi/BFic
+      const MCExpr *BranchTarget;
+      if (MI->getOperand(1).isMBB())
+        BranchTarget = MCSymbolRefExpr::create(
+            MI->getOperand(1).getMBB()->getSymbol(), OutContext);
+      else if (MI->getOperand(1).isGlobal()) {
+        const GlobalValue *GV = MI->getOperand(1).getGlobal();
+        BranchTarget = MCSymbolRefExpr::create(
+            GetARMGVSymbol(GV, MI->getOperand(1).getTargetFlags()), OutContext);
+      } else if (MI->getOperand(1).isSymbol()) {
+        BranchTarget = MCSymbolRefExpr::create(
+            GetExternalSymbolSymbol(MI->getOperand(1).getSymbolName()),
+            OutContext);
+      }
+
+      MCInst.addExpr(BranchTarget);
+    }
+
+      if (Opc == ARM::t2BFic) {
+        const MCExpr *ElseLabel = MCSymbolRefExpr::create(
+            getBFLabel(DL.getPrivateGlobalPrefix(), getFunctionNumber(),
+                       MI->getOperand(2).getIndex(), OutContext),
+            OutContext);
+        MCInst.addExpr(ElseLabel);
+        MCInst.addImm(MI->getOperand(3).getImm());
+      } else {
+        MCInst.addImm(MI->getOperand(2).getImm())
+            .addReg(MI->getOperand(3).getReg());
+      }
+
+    EmitToStreamer(*OutStreamer, MCInst);
+    return;
+  }
+  case ARM::t2BF_LabelPseudo: {
+    // This is a pseudo op for a label used by a branch future instruction
+
+    // Emit the label.
+    OutStreamer->EmitLabel(getBFLabel(DL.getPrivateGlobalPrefix(),
+                                       getFunctionNumber(),
+                                       MI->getOperand(0).getIndex(), OutContext));
+    return;
+  }
   case ARM::tPICADD: {
     // This is a pseudo op for a label + instruction sequence, which looks like:
     // LPC0: