[Lldb-commits] [lldb] [lldb][AArch64] Move register info reconfigure into architecture plugin (PR #70950)

[Jonas Devlieghere via lldb-commits]

================
@@ -762,82 +756,22 @@ uint32_t GDBRemoteRegisterContext::ConvertRegisterKindToRegisterNumber(
   return m_reg_info_sp->ConvertRegisterKindToRegisterNumber(kind, num);
 }
 
-void GDBRemoteRegisterContext::AArch64Reconfigure() {
-  assert(m_reg_info_sp);
-
-  // Once we start to reconfigure registers, we cannot read any of them.
-  // So we must read VG and SVG up front.
-
-  const uint64_t fail_value = LLDB_INVALID_ADDRESS;
-  std::optional<uint64_t> vg_reg_value;
-  const RegisterInfo *vg_reg_info = m_reg_info_sp->GetRegisterInfo("vg");
-  if (vg_reg_info) {
-    // Make sure we get the latest value of vg from the remote.
-    SetRegisterIsValid(vg_reg_info, false);
-    uint32_t vg_reg_num = vg_reg_info->kinds[eRegisterKindLLDB];
-    uint64_t reg_value = ReadRegisterAsUnsigned(vg_reg_num, fail_value);
-    if (reg_value != fail_value && reg_value <= 32)
-      vg_reg_value = reg_value;
-  }
-
-  std::optional<uint64_t> svg_reg_value;
-  const RegisterInfo *svg_reg_info = m_reg_info_sp->GetRegisterInfo("svg");
-  if (svg_reg_info) {
-    // When vg is written it is automatically made invalid. Writing vg will also
-    // change svg if we're in streaming mode but it will not be made invalid
-    // so do this manually so the following read gets the latest svg value.
-    SetRegisterIsValid(svg_reg_info, false);
-
-    uint32_t svg_reg_num = svg_reg_info->kinds[eRegisterKindLLDB];
-    uint64_t reg_value = ReadRegisterAsUnsigned(svg_reg_num, fail_value);
-    if (reg_value != fail_value && reg_value <= 32)
-      svg_reg_value = reg_value;
-  }
-
-  if (vg_reg_value)
-    m_reg_info_sp->UpdateARM64SVERegistersInfos(*vg_reg_value);
-  if (svg_reg_value)
-    m_reg_info_sp->UpdateARM64SMERegistersInfos(*svg_reg_value);
-
-  // At this point if we have updated any registers, their offsets will all be
-  // invalid. If we did, we need to update them all.
-  if (vg_reg_value || svg_reg_value) {
-    m_reg_info_sp->ConfigureOffsets();
-    // From here we are able to read registers again.
-
-    // Make a heap based buffer that is big enough to store all registers
-    m_reg_data.SetData(std::make_shared<DataBufferHeap>(
-        m_reg_info_sp->GetRegisterDataByteSize(), 0));
-    m_reg_data.SetByteOrder(GetByteOrder());
-  }
-}
-
-void GDBRemoteDynamicRegisterInfo::UpdateARM64SVERegistersInfos(uint64_t vg) {
-  // SVE Z register size is vg x 8 bytes.
-  uint32_t z_reg_byte_size = vg * 8;
-
-  // SVE vector length has changed, accordingly set size of Z, P and FFR
-  // registers. Also invalidate register offsets it will be recalculated
-  // after SVE register size update.
-  for (auto &reg : m_regs) {
-    if (reg.value_regs == nullptr) {
-      if (reg.name[0] == 'z' && isdigit(reg.name[1]))
-        reg.byte_size = z_reg_byte_size;
-      else if (reg.name[0] == 'p' && isdigit(reg.name[1]))
-        reg.byte_size = vg;
-      else if (strcmp(reg.name, "ffr") == 0)
-        reg.byte_size = vg;
-    }
-    reg.byte_offset = LLDB_INVALID_INDEX32;
-  }
+bool GDBRemoteRegisterContext::RegisterWriteCausesReconfigure(
+    const char *name) {
+  ExecutionContext exe_ctx(CalculateThread());
+  Process *process = exe_ctx.GetProcessPtr();
+  const Architecture *architecture =
+      process->GetTarget().GetArchitecturePlugin();
+  return architecture && architecture->RegisterWriteCausesReconfigure(name);
 }
 
-void GDBRemoteDynamicRegisterInfo::UpdateARM64SMERegistersInfos(uint64_t svg) {
-  for (auto &reg : m_regs) {
-    if (strcmp(reg.name, "za") == 0) {
-      // ZA is a register with size (svg*8) * (svg*8). A square essentially.
-      reg.byte_size = (svg * 8) * (svg * 8);
-    }
-    reg.byte_offset = LLDB_INVALID_INDEX32;
-  }
+bool GDBRemoteRegisterContext::ReconfigureRegisterInfo() {
+  ExecutionContext exe_ctx(CalculateThread());
+  Process *process = exe_ctx.GetProcessPtr();
----------------
JDevlieghere wrote:

Are you sure this pointer is always valid? If so you should use `GetProcessRef` instead to convey that. Otherwise I'd do something like the snippet below which is a common pattern especially in LLVM. 

```
if (Process *process = exe_ctx.GetProcessPtr()) {
  if (const Architecture *architecture = process->GetTarget().GetArchitecturePlugin()) {
    [...]
  }
}
```

https://github.com/llvm/llvm-project/pull/70950