[LLVM][MIPS] Fix FPU Size Based on Dynamic FR.

Reviewers: jingham, clayborg

Subscribers: jaydeep, bhushan, mohit.bhakkad, slthakur, lldb-commits, emaste, nemanjai, labath, sdardis

Differential Revision: https://reviews.llvm.org/D20357

llvm-svn: 277343

1 files changed, 43 insertions, 0 deletions

diff --git a/lldb/source/Target/RegisterContext.cpp b/lldb/source/Target/RegisterContext.cpp
index 483c932719d..ae3c43def27 100644
--- a/lldb/source/Target/RegisterContext.cpp
+++ b/lldb/source/Target/RegisterContext.cpp
@@ -21,6 +21,9 @@
 #include "lldb/Target/Process.h"
 #include "lldb/Target/Thread.h"
 #include "lldb/Target/Target.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Expression/DWARFExpression.h"
+#include "lldb/Core/Value.h"
 
 using namespace lldb;
 using namespace lldb_private;
@@ -76,6 +79,46 @@ RegisterContext::GetRegisterInfoByName (const char *reg_name, uint32_t start_idx
     return nullptr;
 }
 
+uint32_t
+RegisterContext::UpdateDynamicRegisterSize (const lldb_private::ArchSpec &arch,
+                                            RegisterInfo* reg_info)
+{
+    ExecutionContext exe_ctx (CalculateThread());
+
+    // In MIPS, the floating point registers size is depends on FR bit of SR register.
+    // if SR.FR  == 1 then all floating point registers are 64 bits.
+    // else they are all 32 bits.
+    
+    int expr_result;
+    uint32_t addr_size =  arch.GetAddressByteSize ();
+    const uint8_t* dwarf_opcode_ptr = reg_info->dynamic_size_dwarf_expr_bytes;
+    const size_t dwarf_opcode_len = reg_info->dynamic_size_dwarf_len;
+
+    DataExtractor dwarf_data (dwarf_opcode_ptr, dwarf_opcode_len, 
+                              arch.GetByteOrder (), addr_size);
+    ModuleSP opcode_ctx;
+    DWARFExpression dwarf_expr (opcode_ctx, dwarf_data, nullptr, 0, dwarf_opcode_len);
+    Value result;
+    Error error;
+    const lldb::offset_t offset = 0;
+    if (dwarf_expr.Evaluate (&exe_ctx, nullptr, nullptr, this, opcode_ctx, dwarf_data, nullptr,
+                             offset, dwarf_opcode_len, eRegisterKindDWARF, nullptr, nullptr, result, &error))
+    {
+        expr_result = result.GetScalar ().SInt (-1);
+        switch (expr_result)
+        {
+            case 0: return 4;
+            case 1: return 8;
+            default: return reg_info->byte_size;
+        }
+    }
+    else
+    {
+        printf ("Error executing DwarfExpression::Evaluate %s\n", error.AsCString());
+        return reg_info->byte_size;
+    }
+}
+
 const RegisterInfo *
 RegisterContext::GetRegisterInfo (lldb::RegisterKind kind, uint32_t num)
 {