[lldb] support ieee_single and ieee_double gdbtypes for registers

[satyajanga]

Some gdb remote servers send target.xml that contains

<reg name='ft0' bitsize='32' type='ieee_single' dwarf_regnum='32'/>
  <reg name='ft1' bitsize='32' type='ieee_single' dwarf_regnum='33'/>
  <reg name='ft2' bitsize='32' type='ieee_single' dwarf_regnum='34'/>
  <reg name='ft3' bitsize='32' type='ieee_single' dwarf_regnum='35'/>
  <reg name='ft4' bitsize='32' type='ieee_single' dwarf_regnum='36'/>
  <reg name='ft5' bitsize='32' type='ieee_single' dwarf_regnum='37'/>
  <reg name='ft6' bitsize='32' type='ieee_single' dwarf_regnum='38'/>
  <reg name='ft7' bitsize='32' type='ieee_single' dwarf_regnum='39'/>

it seems like a valid and supported type in gdb.
from gdb16.3/gdb/target_descriptions.c (could not find a way to link it).

case TDESC_TYPE_IEEE_SINGLE:
	  m_type = init_float_type (alloc, -1, "builtin_type_ieee_single",
				    floatformats_ieee_single);
	  return;

case TDESC_TYPE_IEEE_DOUBLE:
	  m_type = init_float_type (alloc, -1, "builtin_type_ieee_double",
				    floatformats_ieee_double);
	  return;

Testplan

updated unittest to test this.

Reviewers: @clayborg , @jeffreytan81 , @Jlalond

[llvmbot]

@llvm/pr-subscribers-lldb

Author: satyanarayana reddy janga (satyajanga)

Changes

Some gdb remote servers send target.xml that contains

<reg name='ft0' bitsize='32' type='ieee_single' dwarf_regnum='32'/>
  <reg name='ft1' bitsize='32' type='ieee_single' dwarf_regnum='33'/>
  <reg name='ft2' bitsize='32' type='ieee_single' dwarf_regnum='34'/>
  <reg name='ft3' bitsize='32' type='ieee_single' dwarf_regnum='35'/>
  <reg name='ft4' bitsize='32' type='ieee_single' dwarf_regnum='36'/>
  <reg name='ft5' bitsize='32' type='ieee_single' dwarf_regnum='37'/>
  <reg name='ft6' bitsize='32' type='ieee_single' dwarf_regnum='38'/>
  <reg name='ft7' bitsize='32' type='ieee_single' dwarf_regnum='39'/>

it seems like a valid and supported type in gdb.
from gdb16.3/gdb/target_descriptions.c (could not find a way to link it).

case TDESC_TYPE_IEEE_SINGLE:
	  m_type = init_float_type (alloc, -1, "builtin_type_ieee_single",
				    floatformats_ieee_single);
	  return;

case TDESC_TYPE_IEEE_DOUBLE:
	  m_type = init_float_type (alloc, -1, "builtin_type_ieee_double",
				    floatformats_ieee_double);
	  return;

Testplan

updated unittest to test this.

---

Full diff: https://github.com/llvm/llvm-project/pull/150268.diff

2 Files Affected:

• (modified) lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp (+2-1)
• (modified) lldb/test/API/functionalities/gdb_remote_client/TestGDBServerTargetXML.py (+11)

diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index a2c34ddfc252e..4c6d584383747 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -4783,7 +4783,8 @@ bool ParseRegisters(
             } else if (gdb_type == "data_ptr" || gdb_type == "code_ptr") {
               reg_info.format = eFormatAddressInfo;
               reg_info.encoding = eEncodingUint;
-            } else if (gdb_type == "float") {
+            } else if (gdb_type == "float" || gdb_type == "ieee_single" ||
+                       gdb_type == "ieee_double") {
               reg_info.format = eFormatFloat;
               reg_info.encoding = eEncodingIEEE754;
             } else if (gdb_type == "aarch64v" ||
diff --git a/lldb/test/API/functionalities/gdb_remote_client/TestGDBServerTargetXML.py b/lldb/test/API/functionalities/gdb_remote_client/TestGDBServerTargetXML.py
index 9a70f67b264ce..db5b5a0e0d0cb 100644
--- a/lldb/test/API/functionalities/gdb_remote_client/TestGDBServerTargetXML.py
+++ b/lldb/test/API/functionalities/gdb_remote_client/TestGDBServerTargetXML.py
@@ -692,6 +692,9 @@ class MyResponder(MockGDBServerResponder):
                 "0102030405060708"  # t4
                 "0102030405060708"  # t5
                 "0102030405060708"  # t6
+                "6162636465666768"  # pc
+                "0000C03F"  # ft0
+                "e07a6147a8a40940"  # ft1
             )
 
             def qXferRead(self, obj, annex, offset, length):
@@ -737,6 +740,10 @@ def qXferRead(self, obj, annex, offset, length):
                                 <reg name="t6" bitsize="64" type="int"/>
                                 <reg name="pc" bitsize="64" type="code_ptr"/>
                             </feature>
+                            <feature name='org.gnu.gdb.riscv.fpu'>
+                                <reg name='ft0' bitsize='32' type='ieee_single'/>
+                                <reg name='ft1' bitsize='64' type='ieee_double'/>
+                            </feature>
                         </target>""",
                         False,
                     )
@@ -799,6 +806,10 @@ def haltReason(self):
         self.match("register read x29", ["t4 = 0x0807060504030201"])
         self.match("register read x30", ["t5 = 0x0807060504030201"])
         self.match("register read x31", ["t6 = 0x0807060504030201"])
+        self.match("register read pc", ["pc = 0x6867666564636261"])
+        # test FPU registers
+        self.match("register read ft0", ["ft0 = 1.5"])
+        self.match("register read ft1", ["ft1 = 3.2053990913985757"])
 
     @skipIfXmlSupportMissing
     @skipIfRemote

[DavidSpickett]

Looks good to me, nice to see more GDB compatibility, but I'll leave it to your chosen reviewers to approve.

[DavidSpickett]

I guess that we just didn't provide data for the PC before? Surprised that the test worked at all.

[satyajanga]

The test also was't validating for pc before. the stop reply packet (from haltReason func) has the PC

[satyajanga]

Looks good to me, nice to see more GDB compatibility, but I'll leave it to your chosen reviewers to approve.

Thank you for your review. the review bot only assigned one reviewer. so I added some more internal reviewers to get faster review.

[Jlalond]

@satyajanga merged for you