Add ldrex and strex instructions to ARM assembler/disassmbler

R=jarin@chromium.org,bmeurer@chromium.org

Review-Url: https://codereview.chromium.org/1993033002
Cr-Commit-Position: refs/heads/master@{#36380}

src/arm/assembler-arm.cc

@@ -2073,6 +2073,53 @@ void Assembler::strd(Register src1, Register src2,
   addrmod3(cond | B7 | B6 | B5 | B4, src1, dst);
 }
 
+// Load/Store exclusive instructions.
+void Assembler::ldrex(Register dst, Register src, Condition cond) {
+  // Instruction details available in ARM DDI 0406C.b, A8.8.75.
+  // cond(31-28) | 00011001(27-20) | Rn(19-16) | Rt(15-12) | 111110011111(11-0)
+  emit(cond | B24 | B23 | B20 | src.code() * B16 | dst.code() * B12 | 0xf9f);
+}
+
+void Assembler::strex(Register src1, Register src2, Register dst,
+                      Condition cond) {
+  // Instruction details available in ARM DDI 0406C.b, A8.8.212.
+  // cond(31-28) | 00011000(27-20) | Rn(19-16) | Rd(15-12) | 11111001(11-4) |
+  // Rt(3-0)
+  emit(cond | B24 | B23 | dst.code() * B16 | src1.code() * B12 | 0xf9 * B4 |
+       src2.code());
+}
+
+void Assembler::ldrexb(Register dst, Register src, Condition cond) {
+  // Instruction details available in ARM DDI 0406C.b, A8.8.76.
+  // cond(31-28) | 00011101(27-20) | Rn(19-16) | Rt(15-12) | 111110011111(11-0)
+  emit(cond | B24 | B23 | B22 | B20 | src.code() * B16 | dst.code() * B12 |
+       0xf9f);
+}
+
+void Assembler::strexb(Register src1, Register src2, Register dst,
+                       Condition cond) {
+  // Instruction details available in ARM DDI 0406C.b, A8.8.213.
+  // cond(31-28) | 00011100(27-20) | Rn(19-16) | Rd(15-12) | 11111001(11-4) |
+  // Rt(3-0)
+  emit(cond | B24 | B23 | B22 | dst.code() * B16 | src1.code() * B12 |
+       0xf9 * B4 | src2.code());
+}
+
+void Assembler::ldrexh(Register dst, Register src, Condition cond) {
+  // Instruction details available in ARM DDI 0406C.b, A8.8.78.
+  // cond(31-28) | 00011111(27-20) | Rn(19-16) | Rt(15-12) | 111110011111(11-0)
+  emit(cond | B24 | B23 | B22 | B21 | B20 | src.code() * B16 |
+       dst.code() * B12 | 0xf9f);
+}
+
+void Assembler::strexh(Register src1, Register src2, Register dst,
+                       Condition cond) {
+  // Instruction details available in ARM DDI 0406C.b, A8.8.215.
+  // cond(31-28) | 00011110(27-20) | Rn(19-16) | Rd(15-12) | 11111001(11-4) |
+  // Rt(3-0)
+  emit(cond | B24 | B23 | B22 | B21 | dst.code() * B16 | src1.code() * B12 |
+       0xf9 * B4 | src2.code());
+}
 
 // Preload instructions.
 void Assembler::pld(const MemOperand& address) {

src/arm/assembler-arm.h

@@ -986,6 +986,14 @@ class Assembler : public AssemblerBase {
             Register src2,
             const MemOperand& dst, Condition cond = al);
 
+  // Load/Store exclusive instructions
+  void ldrex(Register dst, Register src, Condition cond = al);
+  void strex(Register src1, Register src2, Register dst, Condition cond = al);
+  void ldrexb(Register dst, Register src, Condition cond = al);
+  void strexb(Register src1, Register src2, Register dst, Condition cond = al);
+  void ldrexh(Register dst, Register src, Condition cond = al);
+  void strexh(Register src1, Register src2, Register dst, Condition cond = al);
+
   // Preload instructions
   void pld(const MemOperand& address);
 

src/arm/disasm-arm.cc

@@ -755,7 +755,45 @@ void Decoder::DecodeType01(Instruction* instr) {
           Format(instr, "'um'al'cond's 'rd, 'rn, 'rm, 'rs");
         }
       } else {
-        Unknown(instr);  // not used by V8
+        if (instr->Bits(24, 23) == 3) {
+          if (instr->Bit(20) == 1) {
+            // ldrex
+            switch (instr->Bits(22, 21)) {
+              case 0:
+                Format(instr, "ldrex'cond 'rt, ['rn]");
+                break;
+              case 2:
+                Format(instr, "ldrexb'cond 'rt, ['rn]");
+                break;
+              case 3:
+                Format(instr, "ldrexh'cond 'rt, ['rn]");
+                break;
+              default:
+                UNREACHABLE();
+                break;
+            }
+          } else {
+            // strex
+            // The instruction is documented as strex rd, rt, [rn], but the
+            // "rt" register is using the rm bits.
+            switch (instr->Bits(22, 21)) {
+              case 0:
+                Format(instr, "strex'cond 'rd, 'rm, ['rn]");
+                break;
+              case 2:
+                Format(instr, "strexb'cond 'rd, 'rm, ['rn]");
+                break;
+              case 3:
+                Format(instr, "strexh'cond 'rd, 'rm, ['rn]");
+                break;
+              default:
+                UNREACHABLE();
+                break;
+            }
+          }
+        } else {
+          Unknown(instr);  // not used by V8
+        }
       }
     } else if ((instr->Bit(20) == 0) && ((instr->Bits(7, 4) & 0xd) == 0xd)) {
       // ldrd, strd

test/cctest/test-disasm-arm.cc

@@ -1171,3 +1171,17 @@ TEST(Barrier) {
 
   VERIFY_RUN();
 }
+
+
+TEST(LoadStoreExclusive) {
+  SET_UP();
+
+  COMPARE(ldrexb(r0, r1), "e1d10f9f       ldrexb r0, [r1]");
+  COMPARE(strexb(r0, r1, r2), "e1c20f91       strexb r0, r1, [r2]");
+  COMPARE(ldrexh(r0, r1), "e1f10f9f       ldrexh r0, [r1]");
+  COMPARE(strexh(r0, r1, r2), "e1e20f91       strexh r0, r1, [r2]");
+  COMPARE(ldrex(r0, r1), "e1910f9f       ldrex r0, [r1]");
+  COMPARE(strex(r0, r1, r2), "e1820f91       strex r0, r1, [r2]");
+
+  VERIFY_RUN();
+}