omjavaid created this revision.
omjavaid added reviewers: tberghammer, clayborg.
omjavaid added a subscriber: lldb-commits.
Herald added subscribers: rengolin, aemerson.

This patch adds logic to detect if underlying binary is using arm hard float 
abi and use that information while handling return values in ABISysV_arm.

This patch only handles float and double passed using floating point registers.

More return types and argument passing will be handled in a follow up patches.

http://reviews.llvm.org/D16627

Files:
  include/lldb/Core/ArchSpec.h
  source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
  source/Plugins/ABI/SysV-arm/ABISysV_arm.h
  source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

Index: source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
===================================================================
--- source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -1562,6 +1562,15 @@
         }
     }
 
+    if (arch_spec.GetMachine() == llvm::Triple::arm ||
+        arch_spec.GetMachine() == llvm::Triple::thumb)
+    {
+        if (header.e_flags & llvm::ELF::EF_ARM_SOFT_FLOAT)
+            arch_spec.SetFlags (ArchSpec::eARM_abi_soft_float);
+        else if (header.e_flags & llvm::ELF::EF_ARM_VFP_FLOAT)
+            arch_spec.SetFlags (ArchSpec::eARM_abi_hard_float);
+    }
+
     // If there are no section headers we are done.
     if (header.e_shnum == 0)
         return 0;
Index: source/Plugins/ABI/SysV-arm/ABISysV_arm.h
===================================================================
--- source/Plugins/ABI/SysV-arm/ABISysV_arm.h
+++ source/Plugins/ABI/SysV-arm/ABISysV_arm.h
@@ -79,6 +79,9 @@
     const lldb_private::RegisterInfo *
     GetRegisterInfoArray (uint32_t &count) override;
 
+    bool
+    IsArmHardFloat (lldb_private::Thread *thread) const;
+
     //------------------------------------------------------------------
     // Static Functions
     //------------------------------------------------------------------
Index: source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
===================================================================
--- source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
+++ source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
@@ -414,6 +414,25 @@
     return true;
 }
 
+bool
+ABISysV_arm::IsArmHardFloat (Thread *thread) const
+{
+    bool is_armhf = false;
+    if (thread)
+    {
+        ProcessSP process_sp (thread->GetProcess());
+        if (process_sp)
+        {
+            const ArchSpec &arch (process_sp->GetTarget().GetArchitecture());
+            if (arch.GetFlags() == ArchSpec::eARM_abi_hard_float)
+            {
+                is_armhf = true;
+            }
+        }
+    }
+    return is_armhf;
+}
+
 ValueObjectSP
 ABISysV_arm::GetReturnValueObjectImpl (Thread &thread,
                                        lldb_private::CompilerType &compiler_type) const
@@ -516,19 +535,44 @@
                 case 64:
                 {
                     static_assert(sizeof(double) == sizeof(uint64_t), "");
-                    const RegisterInfo *r1_reg_info = reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG2);
-                    uint64_t raw_value;
-                    raw_value = reg_ctx->ReadRegisterAsUnsigned(r0_reg_info, 0) & UINT32_MAX;
-                    raw_value |= ((uint64_t)(reg_ctx->ReadRegisterAsUnsigned(r1_reg_info, 0) & UINT32_MAX)) << 32;
-                    value.GetScalar() = *reinterpret_cast<double*>(&raw_value);
+
+                    if (!IsArmHardFloat(&thread))
+                    {
+                        uint64_t raw_value;
+                        const RegisterInfo *r1_reg_info = reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG2);
+                        raw_value = reg_ctx->ReadRegisterAsUnsigned(r0_reg_info, 0) & UINT32_MAX;
+                        raw_value |= ((uint64_t)(reg_ctx->ReadRegisterAsUnsigned(r1_reg_info, 0) & UINT32_MAX)) << 32;
+                        value.GetScalar() = *reinterpret_cast<double*>(&raw_value);
+                    }
+                    else
+                    {
+                        RegisterValue reg_value;
+                        const RegisterInfo *d0_reg_info = reg_ctx->GetRegisterInfoByName("d0", 0);
+                        reg_ctx->ReadRegister(d0_reg_info, reg_value);
+                        value.GetScalar() = reg_value.GetAsDouble();
+                    }
+
                     break;
                 }
                 case 16: // Half precision returned after a conversion to single precision
                 case 32:
                 {
                     static_assert(sizeof(float) == sizeof(uint32_t), "");
-                    uint32_t raw_value = reg_ctx->ReadRegisterAsUnsigned(r0_reg_info, 0) & UINT32_MAX;
-                    value.GetScalar() = *reinterpret_cast<float*>(&raw_value);
+
+                    if (!IsArmHardFloat(&thread))
+                    {
+                        uint32_t raw_value;
+                        raw_value = reg_ctx->ReadRegisterAsUnsigned(r0_reg_info, 0) & UINT32_MAX;
+                        value.GetScalar() = *reinterpret_cast<float*>(&raw_value);
+                    }
+                    else
+                    {
+                        RegisterValue reg_value;
+                        const RegisterInfo *s0_reg_info = reg_ctx->GetRegisterInfoByName("s0", 0);
+                        reg_ctx->ReadRegister(s0_reg_info, reg_value);
+                        value.GetScalar() = reg_value.GetAsFloat();
+                    }
+
                     break;
                 }
             }
Index: include/lldb/Core/ArchSpec.h
===================================================================
--- include/lldb/Core/ArchSpec.h
+++ include/lldb/Core/ArchSpec.h
@@ -72,6 +72,13 @@
         eMIPSABI_mask       = 0x000ff000
     };
 
+    // ARM specific e_flags
+    enum ARMeflags
+    {
+        eARM_abi_soft_float = 0x00000200,
+        eARM_abi_hard_float = 0x00000400
+    };
+
     enum Core
     {
         eCore_arm_generic,
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