ARMv7 ubfx support

Patch from Kun Zhang <zhangk@codeaurora.org>, see http://codereview.chromium.org/569015.
Review URL: http://codereview.chromium.org/573027

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3804 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/assembler-arm.cc

@@ -51,9 +51,14 @@ void CpuFeatures::Probe() {
   // If the compiler is allowed to use vfp then we can use vfp too in our
   // code generation.
 #if !defined(__arm__)
-  // For the simulator=arm build, always use VFP since the arm simulator has
-  // VFP support.
-  supported_ |= 1u << VFP3;
+  // For the simulator=arm build, use VFP when FLAG_enable_vfp3 is enabled.
+  if (FLAG_enable_vfp3) {
+      supported_ |= 1u << VFP3;
+  }
+  // For the simulator=arm build, use ARMv7 when FLAG_enable_armv7 is enabled
+  if (FLAG_enable_armv7) {
+      supported_ |= 1u << ARMv7;
+  }
 #else
   if (Serializer::enabled()) {
     supported_ |= OS::CpuFeaturesImpliedByPlatform();
@@ -66,6 +71,11 @@ void CpuFeatures::Probe() {
     supported_ |= 1u << VFP3;
     found_by_runtime_probing_ |= 1u << VFP3;
   }
+
+  if (OS::ArmCpuHasFeature(ARMv7)) {
+    supported_ |= 1u << ARMv7;
+    found_by_runtime_probing_ |= 1u << ARMv7;
+  }
 #endif
 }
 
@@ -850,6 +860,21 @@ void Assembler::bx(Register target, Condition cond) {  // v5 and above, plus v4t
 
 
 // Data-processing instructions.
+
+// UBFX <Rd>,<Rn>,#<lsb>,#<width - 1>
+// Instruction details available in ARM DDI 0406A, A8-464.
+// cond(31-28) | 01111(27-23)| 1(22) | 1(21) | widthm1(20-16) |
+//  Rd(15-12) | lsb(11-7) | 101(6-4) | Rn(3-0)
+void Assembler::ubfx(Register dst, Register src1, const Operand& src2,
+                     const Operand& src3, Condition cond) {
+  ASSERT(!src2.rm_.is_valid() && !src3.rm_.is_valid());
+  ASSERT(static_cast<uint32_t>(src2.imm32_) <= 0x1f);
+  ASSERT(static_cast<uint32_t>(src3.imm32_) <= 0x1f);
+  emit(cond | 0x3F*B21 | src3.imm32_*B16 |
+       dst.code()*B12 | src2.imm32_*B7 | 0x5*B4 | src1.code());
+}
+
+
 void Assembler::and_(Register dst, Register src1, const Operand& src2,
                      SBit s, Condition cond) {
   addrmod1(cond | 0*B21 | s, src1, dst, src2);

src/arm/assembler-arm.h

@@ -628,6 +628,9 @@ class Assembler : public Malloced {
   void blx(Label* L)  { blx(branch_offset(L, false)); }  // v5 and above
 
   // Data-processing instructions
+  void ubfx(Register dst, Register src1, const Operand& src2,
+            const Operand& src3, Condition cond = al);
+
   void and_(Register dst, Register src1, const Operand& src2,
             SBit s = LeaveCC, Condition cond = al);
 

src/arm/codegen-arm.cc

@@ -5843,6 +5843,7 @@ const char* GenericBinaryOpStub::GetName() {
 }
 
 
+
 void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
   // r1 : x
   // r0 : y
@@ -6035,9 +6036,7 @@ void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
         case Token::BIT_XOR: __ eor(r0, r0, Operand(r1)); break;
         case Token::SAR:
           // Remove tags from right operand.
-          __ mov(r2, Operand(r0, ASR, kSmiTagSize));  // y
-          // Use only the 5 least significant bits of the shift count.
-          __ and_(r2, r2, Operand(0x1f));
+          __ GetLeastBitsFromSmi(r2, r0, 5);
           __ mov(r0, Operand(r1, ASR, r2));
           // Smi tag result.
           __ bic(r0, r0, Operand(kSmiTagMask));
@@ -6046,9 +6045,7 @@ void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
           // Remove tags from operands.  We can't do this on a 31 bit number
           // because then the 0s get shifted into bit 30 instead of bit 31.
           __ mov(r3, Operand(r1, ASR, kSmiTagSize));  // x
-          __ mov(r2, Operand(r0, ASR, kSmiTagSize));  // y
-          // Use only the 5 least significant bits of the shift count.
-          __ and_(r2, r2, Operand(0x1f));
+          __ GetLeastBitsFromSmi(r2, r0, 5);
           __ mov(r3, Operand(r3, LSR, r2));
           // Unsigned shift is not allowed to produce a negative number, so
           // check the sign bit and the sign bit after Smi tagging.
@@ -6060,9 +6057,7 @@ void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
         case Token::SHL:
           // Remove tags from operands.
           __ mov(r3, Operand(r1, ASR, kSmiTagSize));  // x
-          __ mov(r2, Operand(r0, ASR, kSmiTagSize));  // y
-          // Use only the 5 least significant bits of the shift count.
-          __ and_(r2, r2, Operand(0x1f));
+          __ GetLeastBitsFromSmi(r2, r0, 5);
           __ mov(r3, Operand(r3, LSL, r2));
           // Check that the signed result fits in a Smi.
           __ add(r2, r3, Operand(0x40000000), SetCC);

src/arm/disasm-arm.cc

@@ -429,12 +429,22 @@ int Decoder::FormatOption(Instr* instr, const char* format) {
       return 3;
     }
     case 'o': {
-      if (format[3] == '1') {
+      if ((format[3] == '1') && (format[4] == '2')) {
         // 'off12: 12-bit offset for load and store instructions
         ASSERT(STRING_STARTS_WITH(format, "off12"));
         out_buffer_pos_ += v8i::OS::SNPrintF(out_buffer_ + out_buffer_pos_,
                                              "%d", instr->Offset12Field());
         return 5;
+      } else if ((format[3] == '1') && (format[4] == '6')) {
+        ASSERT(STRING_STARTS_WITH(format, "off16to20"));
+        out_buffer_pos_ += v8i::OS::SNPrintF(out_buffer_ + out_buffer_pos_,
+                                           "%d", instr->Bits(20, 16) +1);
+        return 9;
+      } else if (format[3] == '7') {
+        ASSERT(STRING_STARTS_WITH(format, "off7to11"));
+        out_buffer_pos_ += v8i::OS::SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            "%d", instr->ShiftAmountField());
+        return 8;
       }
       // 'off8: 8-bit offset for extra load and store instructions
       ASSERT(STRING_STARTS_WITH(format, "off8"));
@@ -795,7 +805,18 @@ void Decoder::DecodeType3(Instr* instr) {
       break;
     }
     case 3: {
-      Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
+      if (instr->HasW() && (instr->Bits(6, 4) == 0x5)) {
+        uint32_t widthminus1 = static_cast<uint32_t>(instr->Bits(20, 16));
+        uint32_t lsbit = static_cast<uint32_t>(instr->ShiftAmountField());
+        uint32_t msbit = widthminus1 + lsbit;
+        if (msbit <= 31) {
+          Format(instr, "ubfx'cond 'rd, 'rm, #'off7to11, #'off16to20");
+        } else {
+          UNREACHABLE();
+        }
+      } else {
+        Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
+      }
       break;
     }
     default: {

src/arm/macro-assembler-arm.cc

@@ -1106,6 +1106,18 @@ void MacroAssembler::IntegerToDoubleConversionWithVFP3(Register inReg,
 }
 
 
+void MacroAssembler::GetLeastBitsFromSmi(Register dst,
+                                         Register src,
+                                         int num_least_bits) {
+  if (CpuFeatures::IsSupported(ARMv7)) {
+    ubfx(dst, src, Operand(kSmiTagSize), Operand(num_least_bits - 1));
+  } else {
+    mov(dst, Operand(src, ASR, kSmiTagSize));
+    and_(dst, dst, Operand((1 << num_least_bits) - 1));
+  }
+}
+
+
 void MacroAssembler::CallRuntime(Runtime::Function* f, int num_arguments) {
   // All parameters are on the stack.  r0 has the return value after call.
 

src/arm/macro-assembler-arm.h

@@ -287,6 +287,9 @@ class MacroAssembler: public Assembler {
   // occurred.
   void IllegalOperation(int num_arguments);
 
+  // Get the number of least significant bits from a register
+  void GetLeastBitsFromSmi(Register dst, Register src, int num_least_bits);
+
   // Uses VFP instructions to Convert a Smi to a double.
   void IntegerToDoubleConversionWithVFP3(Register inReg,
                                          Register outHighReg,

src/arm/simulator-arm.cc

@@ -1741,7 +1741,7 @@ void Simulator::DecodeType2(Instr* instr) {
 
 
 void Simulator::DecodeType3(Instr* instr) {
-  ASSERT(instr->Bit(4) == 0);
+  ASSERT(instr->Bits(6, 4) == 0x5 || instr->Bit(4) == 0);
   int rd = instr->RdField();
   int rn = instr->RnField();
   int32_t rn_val = get_register(rn);
@@ -1768,10 +1768,26 @@ void Simulator::DecodeType3(Instr* instr) {
       break;
     }
     case 3: {
-      // Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
-      addr = rn_val + shifter_operand;
-      if (instr->HasW()) {
-        set_register(rn, addr);
+      if (instr->HasW() && (instr->Bits(6, 4) == 0x5)) {
+        uint32_t widthminus1 = static_cast<uint32_t>(instr->Bits(20, 16));
+        uint32_t lsbit = static_cast<uint32_t>(instr->ShiftAmountField());
+        uint32_t msbit = widthminus1 + lsbit;
+        if (msbit <= 31) {
+          uint32_t rm_val =
+              static_cast<uint32_t>(get_register(instr->RmField()));
+          uint32_t extr_val = rm_val << (31 - msbit);
+          extr_val = extr_val >> (31 - widthminus1);
+          set_register(instr->RdField(), extr_val);
+        } else {
+          UNREACHABLE();
+        }
+        return;
+      } else {
+        // Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
+        addr = rn_val + shifter_operand;
+        if (instr->HasW()) {
+          set_register(rn, addr);
+        }
       }
       break;
     }

src/flag-definitions.h

@@ -116,6 +116,8 @@ DEFINE_bool(enable_sahf, true,
             "enable use of SAHF instruction if available (X64 only)")
 DEFINE_bool(enable_vfp3, true,
             "enable use of VFP3 instructions if available (ARM only)")
+DEFINE_bool(enable_armv7, true,
+            "enable use of ARMv7 instructions if available (ARM only)")
 
 // bootstrapper.cc
 DEFINE_string(expose_natives_as, NULL, "expose natives in global object")

src/globals.h

@@ -612,6 +612,7 @@ enum CpuFeature { SSE3 = 32,   // x86
                   RDTSC = 4,   // x86
                   CPUID = 10,  // x86
                   VFP3 = 1,    // ARM
+                  ARMv7 = 2,   // ARM
                   SAHF = 0};   // x86
 
 } }  // namespace v8::internal

src/platform-linux.cc

@@ -89,6 +89,8 @@ uint64_t OS::CpuFeaturesImpliedByPlatform() {
   // Here gcc is telling us that we are on an ARM and gcc is assuming that we
   // have VFP3 instructions.  If gcc can assume it then so can we.
   return 1u << VFP3;
+#elif CAN_USE_ARMV7_INSTRUCTIONS
+  return 1u << ARMv7;
 #else
   return 0;  // Linux runs on anything.
 #endif
@@ -113,6 +115,9 @@ bool OS::ArmCpuHasFeature(CpuFeature feature) {
     case VFP3:
       search_string = "vfp";
       break;
+    case ARMv7:
+      search_string = "ARMv7";
+      break;
     default:
       UNREACHABLE();
   }