[lldb] [ABI/X86] Support combining xmm* and ymm*h regs into ymm*

gdbserver does not expose combined ymm* registers but rather XSAVE-style
split xmm* and ymm*h portions.  Extend value_regs to support combining
multiple registers and use it to create user-friendly ymm* registers
that are combined from split xmm* and ymm*h portions.

Differential Revision: https://reviews.llvm.org/D108937

1 files changed, 60 insertions, 6 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp
index f0225d0..80294ae 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.cpp
@@ -87,10 +87,34 @@ bool GDBRemoteRegisterContext::ReadRegister(const RegisterInfo *reg_info,
     const uint32_t reg = reg_info->kinds[eRegisterKindLLDB];
     if (m_reg_valid[reg] == false)
       return false;
-    const bool partial_data_ok = false;
-    Status error(value.SetValueFromData(
-        reg_info, m_reg_data, reg_info->byte_offset, partial_data_ok));
-    return error.Success();
+    if (reg_info->value_regs &&
+        reg_info->value_regs[0] != LLDB_INVALID_REGNUM &&
+        reg_info->value_regs[1] != LLDB_INVALID_REGNUM) {
+      std::vector<char> combined_data;
+      uint32_t offset = 0;
+      for (int i = 0; reg_info->value_regs[i] != LLDB_INVALID_REGNUM; i++) {
+        const RegisterInfo *parent_reg = GetRegisterInfo(
+            eRegisterKindLLDB, reg_info->value_regs[i]);
+        if (!parent_reg)
+          return false;
+        combined_data.resize(offset + parent_reg->byte_size);
+        if (m_reg_data.CopyData(parent_reg->byte_offset, parent_reg->byte_size,
+                                combined_data.data() + offset) !=
+            parent_reg->byte_size)
+          return false;
+        offset += parent_reg->byte_size;
+      }
+
+      Status error;
+      return value.SetFromMemoryData(
+                 reg_info, combined_data.data(), combined_data.size(),
+                 m_reg_data.GetByteOrder(), error) == combined_data.size();
+    } else {
+      const bool partial_data_ok = false;
+      Status error(value.SetValueFromData(
+          reg_info, m_reg_data, reg_info->byte_offset, partial_data_ok));
+      return error.Success();
+    }
   }
   return false;
 }
@@ -272,8 +296,38 @@ bool GDBRemoteRegisterContext::ReadRegisterBytes(const RegisterInfo *reg_info) {
 bool GDBRemoteRegisterContext::WriteRegister(const RegisterInfo *reg_info,
                                              const RegisterValue &value) {
   DataExtractor data;
-  if (value.GetData(data))
-    return WriteRegisterBytes(reg_info, data, 0);
+  if (value.GetData(data)) {
+    if (reg_info->value_regs &&
+        reg_info->value_regs[0] != LLDB_INVALID_REGNUM &&
+        reg_info->value_regs[1] != LLDB_INVALID_REGNUM) {
+      uint32_t combined_size = 0;
+      for (int i = 0; reg_info->value_regs[i] != LLDB_INVALID_REGNUM; i++) {
+        const RegisterInfo *parent_reg = GetRegisterInfo(
+            eRegisterKindLLDB, reg_info->value_regs[i]);
+        if (!parent_reg)
+          return false;
+        combined_size += parent_reg->byte_size;
+      }
+
+      if (data.GetByteSize() < combined_size)
+        return false;
+
+      uint32_t offset = 0;
+      for (int i = 0; reg_info->value_regs[i] != LLDB_INVALID_REGNUM; i++) {
+        const RegisterInfo *parent_reg = GetRegisterInfo(
+            eRegisterKindLLDB, reg_info->value_regs[i]);
+        assert(parent_reg);
+
+        DataExtractor parent_data{data, offset, parent_reg->byte_size};
+        if (!WriteRegisterBytes(parent_reg, parent_data, 0))
+          return false;
+        offset += parent_reg->byte_size;
+      }
+      assert(offset == combined_size);
+      return true;
+    } else
+      return WriteRegisterBytes(reg_info, data, 0);
+  }
   return false;
 }