Revert of [turbofan] ARM: Implement vswp and use in gap resolver (patchset #2 id:20001 of https://codereview.chromium.org/2313803003/ )

Reason for revert:
Breaks arm compilation:
https://build.chromium.org/p/client.v8.ports/builders/V8%20Arm%20-%20builder/builds/3549

Original issue's description:
> [turbofan] ARM: Implement vswp and use in gap resolver
>
> Use vswp to switch double-precision registers in the gap resolver, with fall
> back temp register-based code if NEON is not available.
>
> BUG=
>
> Committed: https://crrev.com/2837c2e65a2ee5b9fc610f30ce1215f52323ecbd
> Cr-Commit-Position: refs/heads/master@{#39209}

TBR=bmeurer@chromium.org,epertoso@chromium.org,martyn.capewell@arm.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review-Url: https://codereview.chromium.org/2314003003
Cr-Commit-Position: refs/heads/master@{#39210}

src/arm/assembler-arm.cc

@@ -3905,27 +3905,6 @@ void Assembler::vmovl(NeonDataType dt, QwNeonRegister dst, DwVfpRegister src) {
         (dt & NeonDataTypeSizeMask)*B19 | vd*B12 | 0xA*B8 | m*B5 | B4 | vm);
 }
 
-void Assembler::vswp(DwVfpRegister srcdst0, DwVfpRegister srcdst1) {
-  DCHECK(!srcdst0.is(kScratchDoubleReg));
-  DCHECK(!srcdst1.is(kScratchDoubleReg));
-
-  if (srcdst0.is(srcdst1)) return;  // Swapping aliased registers emits nothing.
-
-  if (CpuFeatures::IsSupported(NEON)) {
-    // Instruction details available in ARM DDI 0406C.b, A8.8.418.
-    // 1111(31-28) | 00111(27-23) | D(22) | 110010(21-16) |
-    // Vd(15-12) | 000000(11-6) | M(5) | 0(4) | Vm(3-0)
-    int vd, d;
-    srcdst0.split_code(&vd, &d);
-    int vm, m;
-    srcdst1.split_code(&vm, &m);
-    emit(0xF * B28 | 7 * B23 | d * B22 | 0x32 * B16 | vd * B12 | m * B5 | vm);
-  } else {
-    vmov(kScratchDoubleReg, srcdst0);
-    vmov(srcdst0, srcdst1);
-    vmov(srcdst1, kScratchDoubleReg);
-  }
-}
 
 // Pseudo instructions.
 void Assembler::nop(int type) {

src/arm/assembler-arm.h

@@ -1303,8 +1303,8 @@ class Assembler : public AssemblerBase {
               const Condition cond = al);
 
   // Support for NEON.
-
   // All these APIs support D0 to D31 and Q0 to Q15.
+
   void vld1(NeonSize size,
             const NeonListOperand& dst,
             const NeonMemOperand& src);
@@ -1313,9 +1313,6 @@ class Assembler : public AssemblerBase {
             const NeonMemOperand& dst);
   void vmovl(NeonDataType dt, QwNeonRegister dst, DwVfpRegister src);
 
-  // Currently, vswp supports only D0 to D31.
-  void vswp(DwVfpRegister srcdst0, DwVfpRegister srcdst1);
-
   // Pseudo instructions
 
   // Different nop operations are used by the code generator to detect certain

src/arm/disasm-arm.cc

@@ -1825,13 +1825,6 @@ void Decoder::DecodeSpecialCondition(Instruction* instr) {
         int imm3 = instr->Bits(21, 19);
         out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
                                     "vmovl.u%d q%d, d%d", imm3*8, Vd, Vm);
-      } else if ((instr->Bits(21, 16) == 0x32) && (instr->Bits(11, 7) == 0) &&
-                 (instr->Bit(4) == 0)) {
-        int Vd = instr->VFPDRegValue(kDoublePrecision);
-        int Vm = instr->VFPMRegValue(kDoublePrecision);
-        char rtype = (instr->Bit(6) == 0) ? 'd' : 'q';
-        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
-                                    "vswp %c%d, %c%d", rtype, Vd, rtype, Vm);
       } else {
         Unknown(instr);
       }

src/arm/macro-assembler-arm.cc

@@ -1054,7 +1054,6 @@ void MacroAssembler::VmovLow(DwVfpRegister dst, Register src) {
     vmov(dst, VmovIndexLo, src);
   }
 }
-
 void MacroAssembler::LslPair(Register dst_low, Register dst_high,
                              Register src_low, Register src_high,
                              Register scratch, Register shift) {

src/arm/simulator-arm.cc

@@ -3783,21 +3783,6 @@ void Simulator::DecodeSpecialCondition(Instruction* instr) {
           e++;
         }
         set_q_register(Vd, reinterpret_cast<uint64_t*>(to));
-      } else if ((instr->Bits(21, 16) == 0x32) && (instr->Bits(11, 7) == 0) &&
-                 (instr->Bit(4) == 0)) {
-        int vd = instr->VFPDRegValue(kDoublePrecision);
-        int vm = instr->VFPMRegValue(kDoublePrecision);
-        if (instr->Bit(6) == 0) {
-          // vswp Dd, Dm.
-          uint64_t dval, mval;
-          get_d_register(vd, &dval);
-          get_d_register(vm, &mval);
-          set_d_register(vm, &dval);
-          set_d_register(vd, &mval);
-        } else {
-          // Q register vswp unimplemented.
-          UNIMPLEMENTED();
-        }
       } else {
         UNIMPLEMENTED();
       }

src/compiler/arm/code-generator-arm.cc

@@ -1912,31 +1912,33 @@ void CodeGenerator::AssembleSwap(InstructionOperand* source,
     __ vstr(temp_1, src);
   } else if (source->IsFPRegister()) {
     LowDwVfpRegister temp = kScratchDoubleReg;
-    DwVfpRegister src = g.ToDoubleRegister(source);
+      DwVfpRegister src = g.ToDoubleRegister(source);
-    if (destination->IsFPRegister()) {
+      if (destination->IsFPRegister()) {
-      DwVfpRegister dst = g.ToDoubleRegister(destination);
+        DwVfpRegister dst = g.ToDoubleRegister(destination);
-      __ vswp(src, dst);
+        __ Move(temp, src);
-    } else {
+        __ Move(src, dst);
-      DCHECK(destination->IsFPStackSlot());
+        __ Move(dst, temp);
-      MemOperand dst = g.ToMemOperand(destination);
+      } else {
-      __ Move(temp, src);
+        DCHECK(destination->IsFPStackSlot());
-      __ vldr(src, dst);
+        MemOperand dst = g.ToMemOperand(destination);
-      __ vstr(temp, dst);
+        __ Move(temp, src);
-    }
+        __ vldr(src, dst);
+        __ vstr(temp, dst);
+      }
   } else if (source->IsFPStackSlot()) {
     DCHECK(destination->IsFPStackSlot());
     Register temp_0 = kScratchReg;
     LowDwVfpRegister temp_1 = kScratchDoubleReg;
     MemOperand src0 = g.ToMemOperand(source);
     MemOperand dst0 = g.ToMemOperand(destination);
-    MemOperand src1(src0.rn(), src0.offset() + kPointerSize);
+      MemOperand src1(src0.rn(), src0.offset() + kPointerSize);
-    MemOperand dst1(dst0.rn(), dst0.offset() + kPointerSize);
+      MemOperand dst1(dst0.rn(), dst0.offset() + kPointerSize);
-    __ vldr(temp_1, dst0);  // Save destination in temp_1.
+      __ vldr(temp_1, dst0);  // Save destination in temp_1.
-    __ ldr(temp_0, src0);   // Then use temp_0 to copy source to destination.
+      __ ldr(temp_0, src0);   // Then use temp_0 to copy source to destination.
-    __ str(temp_0, dst0);
+      __ str(temp_0, dst0);
-    __ ldr(temp_0, src1);
+      __ ldr(temp_0, src1);
-    __ str(temp_0, dst1);
+      __ str(temp_0, dst1);
-    __ vstr(temp_1, src0);
+      __ vstr(temp_1, src0);
   } else {
     // No other combinations are possible.
     UNREACHABLE();

test/cctest/test-assembler-arm.cc

@@ -2889,55 +2889,6 @@ TEST(unaligned_stores) {
   }
 }
 
-TEST(vswp) {
-  CcTest::InitializeVM();
-  Isolate* isolate = CcTest::i_isolate();
-  HandleScope scope(isolate);
-  Assembler assm(isolate, NULL, 0);
-
-  typedef struct {
-    double result0;
-    double result1;
-    double result2;
-    double result3;
-  } T;
-  T t;
-
-  __ vmov(d0, 1.0);
-  __ vmov(d1, -1.0);
-  __ vswp(d0, d1);
-  __ vstr(d0, r0, offsetof(T, result0));
-  __ vstr(d1, r0, offsetof(T, result1));
-
-  if (CpuFeatures::IsSupported(VFP32DREGS)) {
-    __ vmov(d30, 1.0);
-    __ vmov(d31, -1.0);
-    __ vswp(d30, d31);
-    __ vstr(d30, r0, offsetof(T, result2));
-    __ vstr(d31, r0, offsetof(T, result3));
-  }
-
-  __ bx(lr);
-
-  CodeDesc desc;
-  assm.GetCode(&desc);
-  Handle<Code> code = isolate->factory()->NewCode(
-      desc, Code::ComputeFlags(Code::STUB), Handle<Code>());
-#ifdef DEBUG
-  OFStream os(stdout);
-  code->Print(os);
-#endif
-  F3 f = FUNCTION_CAST<F3>(code->entry());
-  Object* dummy = CALL_GENERATED_CODE(isolate, f, &t, 0, 0, 0, 0);
-  USE(dummy);
-  CHECK_EQ(-1.0, t.result0);
-  CHECK_EQ(1.0, t.result1);
-  if (CpuFeatures::IsSupported(VFP32DREGS)) {
-    CHECK_EQ(-1.0, t.result2);
-    CHECK_EQ(1.0, t.result3);
-  }
-}
-
 TEST(regress4292_b) {
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();

test/cctest/test-disasm-arm.cc

@@ -932,10 +932,6 @@ TEST(Neon) {
               "f3886a11       vmovl.u8 q3, d1");
       COMPARE(vmovl(NeonU8, q4, d2),
               "f3888a12       vmovl.u8 q4, d2");
-      COMPARE(vswp(d0, d31),
-              "f3b2002f       vswp d0, d31");
-      COMPARE(vswp(d16, d14),
-              "f3f2000e       vswp d16, d14");
   }
 
   VERIFY_RUN();