[arm] Print address for load literal instructions.

BUG=

Review-Url: https://codereview.chromium.org/2871863003
Cr-Commit-Position: refs/heads/master@{#45297}

src/arm/disasm-arm.cc

@@ -667,6 +667,28 @@ int Decoder::FormatOption(Instruction* instr, const char* format) {
     case 'v': {
       return FormatVFPinstruction(instr, format);
     }
+    case 'A': {
+      // Print pc-relative address.
+      int offset = instr->Offset12Value();
+      byte* pc = reinterpret_cast<byte*>(instr) + Instruction::kPCReadOffset;
+      byte* addr;
+      switch (instr->PUField()) {
+        case db_x: {
+          addr = pc - offset;
+          break;
+        }
+        case ib_x: {
+          addr = pc + offset;
+          break;
+        }
+        default: {
+          UNREACHABLE();
+          return -1;
+        }
+      }
+      out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%p", addr);
+      return 1;
+    }
     case 'S':
     case 'D': {
       return FormatVFPRegister(instr, format);
@@ -1033,11 +1055,19 @@ void Decoder::DecodeType2(Instruction* instr) {
       break;
     }
     case db_x: {
-      Format(instr, "'memop'cond'b 'rd, ['rn, #-'off12]'w");
+      if (instr->HasL() && (instr->RnValue() == kPCRegister)) {
+        Format(instr, "'memop'cond'b 'rd, [pc, #-'off12]'w (addr 'A)");
+      } else {
+        Format(instr, "'memop'cond'b 'rd, ['rn, #-'off12]'w");
+      }
       break;
     }
     case ib_x: {
-      Format(instr, "'memop'cond'b 'rd, ['rn, #+'off12]'w");
+      if (instr->HasL() && (instr->RnValue() == kPCRegister)) {
+        Format(instr, "'memop'cond'b 'rd, [pc, #+'off12]'w (addr 'A)");
+      } else {
+        Format(instr, "'memop'cond'b 'rd, ['rn, #+'off12]'w");
+      }
       break;
     }
     default: {

test/cctest/test-disasm-arm.cc

@@ -1393,6 +1393,39 @@ TEST(LoadStore) {
 }
 
 
+static void TestLoadLiteral(byte* buffer, Assembler* assm, bool* failure,
+                            int offset) {
+  int pc_offset = assm->pc_offset();
+  byte *progcounter = &buffer[pc_offset];
+  assm->ldr(r0, MemOperand(pc, offset));
+
+  const char *expected_string_template =
+    (offset >= 0) ?
+    "e59f0%03x       ldr r0, [pc, #+%d] (addr %p)" :
+    "e51f0%03x       ldr r0, [pc, #%d] (addr %p)";
+  char expected_string[80];
+  snprintf(expected_string, sizeof(expected_string), expected_string_template,
+           abs(offset), offset,
+           progcounter + Instruction::kPCReadOffset + offset);
+  if (!DisassembleAndCompare(progcounter, expected_string)) *failure = true;
+}
+
+
+TEST(LoadLiteral) {
+  SET_UP();
+
+  TestLoadLiteral(buffer, &assm, &failure, 0);
+  TestLoadLiteral(buffer, &assm, &failure, 1);
+  TestLoadLiteral(buffer, &assm, &failure, 4);
+  TestLoadLiteral(buffer, &assm, &failure, 4095);
+  TestLoadLiteral(buffer, &assm, &failure, -1);
+  TestLoadLiteral(buffer, &assm, &failure, -4);
+  TestLoadLiteral(buffer, &assm, &failure, -4095);
+
+  VERIFY_RUN();
+}
+
+
 TEST(Barrier) {
   SET_UP();