ARM: Fix literal pool handling for breakpoints in debugger....

src/assembler.cc

Index: src/assembler.cc
===================================================================
--- src/assembler.cc	(revision 11811)
+++ src/assembler.cc	(working copy)
@@ -141,7 +141,7 @@
 // an iteration.
 //
 // The encoding relies on the fact that there are fewer than 14
-// different non-compactly encoded relocation modes.
+// different relocation modes using standard non-compact encoding.
 //
 // The first byte of a relocation record has a tag in its low 2 bits:
 // Here are the record schemes, depending on the low tag and optional higher
@@ -173,7 +173,9 @@
 //                              00 [4 bit middle_tag] 11 followed by
 //                              00 [6 bit pc delta]
 //
-//      1101: not used (would allow one more relocation mode to be added)
+//      1101: constant pool. Used on ARM only for now.
+//        The format is:       11 1101 11
+//                             signed int (size of the constant pool).
 //      1110: long_data_record
 //        The format is:       [2-bit data_type_tag] 1110 11
 //                             signed intptr_t, lowest byte written first
@@ -194,7 +196,7 @@
 //                dropped, and last non-zero chunk tagged with 1.)
 
 
-const int kMaxRelocModes = 14;
+const int kMaxStandardNonCompactModes = 14;
 
 const int kTagBits = 2;
 const int kTagMask = (1 << kTagBits) - 1;
@@ -228,7 +230,10 @@
 const int kStatementPositionTag = 2;
 const int kCommentTag = 3;
 
+const int kConstPoolExtraTag = kPCJumpExtraTag - 2;
+const int kConstPoolTag = 3;
 
+
 uint32_t RelocInfoWriter::WriteVariableLengthPCJump(uint32_t pc_delta) {
   // Return if the pc_delta can fit in kSmallPCDeltaBits bits.
   // Otherwise write a variable length PC jump for the bits that do
@@ -285,6 +290,15 @@
   }
 }
 
+void RelocInfoWriter::WriteExtraTaggedConstPoolData(int data) {
+  WriteExtraTag(kConstPoolExtraTag, kConstPoolTag);
+  for (int i = 0; i < kIntSize; i++) {
+    *--pos_ = static_cast<byte>(data);
+    // Signed right shift is arithmetic shift.  Tested in test-utils.cc.
+    data = data >> kBitsPerByte;
+  }
+}
+
 void RelocInfoWriter::WriteExtraTaggedData(intptr_t data_delta, int top_tag) {
   WriteExtraTag(kDataJumpExtraTag, top_tag);
   for (int i = 0; i < kIntptrSize; i++) {
@@ -300,8 +314,8 @@
   byte* begin_pos = pos_;
 #endif
   ASSERT(rinfo->pc() - last_pc_ >= 0);
-  ASSERT(RelocInfo::NUMBER_OF_MODES - RelocInfo::LAST_COMPACT_ENUM <=
-         kMaxRelocModes);
+  ASSERT(RelocInfo::LAST_STANDARD_NONCOMPACT_ENUM - RelocInfo::LAST_COMPACT_ENUM
+         <= kMaxStandardNonCompactModes);
   // Use unsigned delta-encoding for pc.
   uint32_t pc_delta = static_cast<uint32_t>(rinfo->pc() - last_pc_);
   RelocInfo::Mode rmode = rinfo->rmode();
@@ -347,6 +361,9 @@
     WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
     WriteExtraTaggedData(rinfo->data(), kCommentTag);
     ASSERT(begin_pos - pos_ >= RelocInfo::kMinRelocCommentSize);
+  } else if (RelocInfo::IsConstPool(rmode)) {
+      WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
+      WriteExtraTaggedConstPoolData(rinfo->data());
   } else {
     ASSERT(rmode > RelocInfo::LAST_COMPACT_ENUM);
     int saved_mode = rmode - RelocInfo::LAST_COMPACT_ENUM;
@@ -397,6 +414,15 @@
 }
 
 
+void RelocIterator::AdvanceReadConstPoolData() {
+  int x = 0;
+  for (int i = 0; i < kIntSize; i++) {
+    x |= static_cast<int>(*--pos_) << i * kBitsPerByte;
+  }
+  rinfo_.data_ = x;
+}
+
+
 void RelocIterator::AdvanceReadPosition() {
   int x = 0;
   for (int i = 0; i < kIntSize; i++) {
@@ -500,8 +526,7 @@
       ASSERT(tag == kDefaultTag);
       int extra_tag = GetExtraTag();
       if (extra_tag == kPCJumpExtraTag) {
-        int top_tag = GetTopTag();
-        if (top_tag == kVariableLengthPCJumpTopTag) {
+        if (GetTopTag() == kVariableLengthPCJumpTopTag) {
           AdvanceReadVariableLengthPCJump();
         } else {
           AdvanceReadPC();
@@ -531,6 +556,13 @@
           }
           Advance(kIntptrSize);
         }
+      } else if ((extra_tag == kConstPoolExtraTag) &&
+                 (GetTopTag() == kConstPoolTag)) {
+        if (SetMode(RelocInfo::CONST_POOL)) {
+          AdvanceReadConstPoolData();
+          return;
+        }
+        Advance(kIntSize);
       } else {
         AdvanceReadPC();
         int rmode = extra_tag + RelocInfo::LAST_COMPACT_ENUM;
@@ -613,6 +645,8 @@
       return "external reference";
     case RelocInfo::INTERNAL_REFERENCE:
       return "internal reference";
+    case RelocInfo::CONST_POOL:
+      return "constant pool";
     case RelocInfo::DEBUG_BREAK_SLOT:
 #ifndef ENABLE_DEBUGGER_SUPPORT
       UNREACHABLE();
@@ -698,6 +732,7 @@
     case STATEMENT_POSITION:
     case EXTERNAL_REFERENCE:
     case INTERNAL_REFERENCE:
+    case CONST_POOL:
     case DEBUG_BREAK_SLOT:
     case NONE:
       break;