From 2de8c1691304420d2f1050f31c9f25e043ab7874 Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard@arm.com>
Date: Wed, 16 Dec 2015 12:37:39 +0000
Subject: [ARM] Add ARMv8.2-A FP16 vector instructions

ARMv8.2-A adds 16-bit floating point versions of all existing SIMD
floating-point instructions. This is an optional extension, so all of
these instructions require the FeatureFullFP16 subtarget feature.

Note that VFP without SIMD is not a valid combination for any version of
ARMv8-A, but I have ensured that these instructions all depend on both
FeatureNEON and FeatureFullFP16 for consistency.

Differential Revision: http://reviews.llvm.org/D15039

llvm-svn: 255764
---
 .../Target/ARM/Disassembler/ARMDisassembler.cpp    | 74 +++++++++++++++++++---
 1 file changed, 66 insertions(+), 8 deletions(-)

(limited to 'llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp')

diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index a05111e4ceb..bc63c26b328 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -5073,6 +5073,10 @@ static DecodeStatus DecodeSwap(MCInst &Inst, unsigned Insn,
 
 static DecodeStatus DecodeVCVTD(MCInst &Inst, unsigned Insn,
                                 uint64_t Address, const void *Decoder) {
+  const FeatureBitset &featureBits =
+      ((const MCDisassembler *)Decoder)->getSubtargetInfo().getFeatureBits();
+  bool hasFullFP16 = featureBits[ARM::FeatureFullFP16];
+
   unsigned Vd = (fieldFromInstruction(Insn, 12, 4) << 0);
   Vd |= (fieldFromInstruction(Insn, 22, 1) << 4);
   unsigned Vm = (fieldFromInstruction(Insn, 0, 4) << 0);
@@ -5083,10 +5087,35 @@ static DecodeStatus DecodeVCVTD(MCInst &Inst, unsigned Insn,
 
   DecodeStatus S = MCDisassembler::Success;
 
-  // VMOVv2f32 is ambiguous with these decodings.
-  if (!(imm & 0x38) && cmode == 0xF) {
-    if (op == 1) return MCDisassembler::Fail;
-    Inst.setOpcode(ARM::VMOVv2f32);
+  // If the top 3 bits of imm are clear, this is a VMOV (immediate)
+  if (!(imm & 0x38)) {
+    if (cmode == 0xF) {
+      if (op == 1) return MCDisassembler::Fail;
+      Inst.setOpcode(ARM::VMOVv2f32);
+    }
+    if (hasFullFP16) {
+      if (cmode == 0xE) {
+        if (op == 1) {
+          Inst.setOpcode(ARM::VMOVv1i64);
+        } else {
+          Inst.setOpcode(ARM::VMOVv8i8);
+        }
+      }
+      if (cmode == 0xD) {
+        if (op == 1) {
+          Inst.setOpcode(ARM::VMVNv2i32);
+        } else {
+          Inst.setOpcode(ARM::VMOVv2i32);
+        }
+      }
+      if (cmode == 0xC) {
+        if (op == 1) {
+          Inst.setOpcode(ARM::VMVNv2i32);
+        } else {
+          Inst.setOpcode(ARM::VMOVv2i32);
+        }
+      }
+    }
     return DecodeNEONModImmInstruction(Inst, Insn, Address, Decoder);
   }
 
@@ -5103,6 +5132,10 @@ static DecodeStatus DecodeVCVTD(MCInst &Inst, unsigned Insn,
 
 static DecodeStatus DecodeVCVTQ(MCInst &Inst, unsigned Insn,
                                 uint64_t Address, const void *Decoder) {
+  const FeatureBitset &featureBits =
+      ((const MCDisassembler *)Decoder)->getSubtargetInfo().getFeatureBits();
+  bool hasFullFP16 = featureBits[ARM::FeatureFullFP16];
+
   unsigned Vd = (fieldFromInstruction(Insn, 12, 4) << 0);
   Vd |= (fieldFromInstruction(Insn, 22, 1) << 4);
   unsigned Vm = (fieldFromInstruction(Insn, 0, 4) << 0);
@@ -5113,10 +5146,35 @@ static DecodeStatus DecodeVCVTQ(MCInst &Inst, unsigned Insn,
 
   DecodeStatus S = MCDisassembler::Success;
 
-  // VMOVv4f32 is ambiguous with these decodings.
-  if (!(imm & 0x38) && cmode == 0xF) {
-    if (op == 1) return MCDisassembler::Fail;
-    Inst.setOpcode(ARM::VMOVv4f32);
+  // If the top 3 bits of imm are clear, this is a VMOV (immediate)
+  if (!(imm & 0x38)) {
+    if (cmode == 0xF) {
+      if (op == 1) return MCDisassembler::Fail;
+      Inst.setOpcode(ARM::VMOVv4f32);
+    }
+    if (hasFullFP16) {
+      if (cmode == 0xE) {
+        if (op == 1) {
+          Inst.setOpcode(ARM::VMOVv2i64);
+        } else {
+          Inst.setOpcode(ARM::VMOVv16i8);
+        }
+      }
+      if (cmode == 0xD) {
+        if (op == 1) {
+          Inst.setOpcode(ARM::VMVNv4i32);
+        } else {
+          Inst.setOpcode(ARM::VMOVv4i32);
+        }
+      }
+      if (cmode == 0xC) {
+        if (op == 1) {
+          Inst.setOpcode(ARM::VMVNv4i32);
+        } else {
+          Inst.setOpcode(ARM::VMOVv4i32);
+        }
+      }
+    }
     return DecodeNEONModImmInstruction(Inst, Insn, Address, Decoder);
   }
 
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