[lldb] Remove Function null checks in Block.cpp (#137611)

As of #117683, Blocks are always enclosed in a function, so these checks
never fail. We can't change the signature of
`CalculateSymbolContextFunction` as it's an abstract function (and some
of its implementations can return nullptr), but we can create a
different function that we can call when we know we're dealing with a
block.

Author: labath

lldb/include/lldb/Symbol/Block.h

@@ -78,6 +78,8 @@ class Block : public UserID, public SymbolContextScope {
 
   Block *CalculateSymbolContextBlock() override;
 
+  Function &GetFunction();
+
   /// Check if an offset is in one of the block offset ranges.
   ///
   /// \param[in] range_offset

lldb/source/Symbol/Block.cpp

@@ -153,10 +153,16 @@ Function *Block::CalculateSymbolContextFunction() {
 
 Block *Block::CalculateSymbolContextBlock() { return this; }
 
-void Block::DumpSymbolContext(Stream *s) {
+Function &Block::GetFunction() {
+  // Blocks always have an enclosing function because their parent is either a
+  // function or a block (which has a parent, inductively).
   Function *function = CalculateSymbolContextFunction();
-  if (function)
-    function->DumpSymbolContext(s);
+  assert(function);
+  return *function;
+}
+
+void Block::DumpSymbolContext(Stream *s) {
+  GetFunction().DumpSymbolContext(s);
   s->Printf(", Block{0x%8.8" PRIx64 "}", GetID());
 }
 
@@ -241,20 +247,17 @@ bool Block::GetRangeContainingOffset(const addr_t offset, Range &range) {
 
 bool Block::GetRangeContainingAddress(const Address &addr,
                                       AddressRange &range) {
-  Function *function = CalculateSymbolContextFunction();
-  if (function) {
-    if (uint32_t idx = GetRangeIndexContainingAddress(addr);
-        idx != UINT32_MAX) {
-      const Range *range_ptr = m_ranges.GetEntryAtIndex(idx);
-      assert(range_ptr);
-
-      Address func_addr = function->GetAddress();
-      range.GetBaseAddress() =
-          Address(func_addr.GetFileAddress() + range_ptr->GetRangeBase(),
-                  func_addr.GetModule()->GetSectionList());
-      range.SetByteSize(range_ptr->GetByteSize());
-      return true;
-    }
+  Function &function = GetFunction();
+  if (uint32_t idx = GetRangeIndexContainingAddress(addr); idx != UINT32_MAX) {
+    const Range *range_ptr = m_ranges.GetEntryAtIndex(idx);
+    assert(range_ptr);
+
+    Address func_addr = function.GetAddress();
+    range.GetBaseAddress() =
+        Address(func_addr.GetFileAddress() + range_ptr->GetRangeBase(),
+                func_addr.GetModule()->GetSectionList());
+    range.SetByteSize(range_ptr->GetByteSize());
+    return true;
   }
   range.Clear();
   return false;
@@ -269,11 +272,9 @@ bool Block::GetRangeContainingLoadAddress(lldb::addr_t load_addr,
 }
 
 uint32_t Block::GetRangeIndexContainingAddress(const Address &addr) {
-  Function *function = CalculateSymbolContextFunction();
-  if (!function)
-    return UINT32_MAX;
+  Function &function = GetFunction();
 
-  const Address &func_addr = function->GetAddress();
+  const Address &func_addr = function.GetAddress();
   if (addr.GetModule() != func_addr.GetModule())
     return UINT32_MAX;
 
@@ -283,29 +284,25 @@ uint32_t Block::GetRangeIndexContainingAddress(const Address &addr) {
 }
 
 bool Block::GetRangeAtIndex(uint32_t range_idx, AddressRange &range) {
-  if (range_idx < m_ranges.GetSize()) {
-    Function *function = CalculateSymbolContextFunction();
-    if (function) {
-      const Range &vm_range = m_ranges.GetEntryRef(range_idx);
-      range.GetBaseAddress() = function->GetAddress();
-      range.GetBaseAddress().Slide(vm_range.GetRangeBase());
-      range.SetByteSize(vm_range.GetByteSize());
-      return true;
-    }
-  }
-  return false;
+  if (range_idx >= m_ranges.GetSize())
+    return false;
+
+  Function &function = GetFunction();
+  const Range &vm_range = m_ranges.GetEntryRef(range_idx);
+  range.GetBaseAddress() = function.GetAddress();
+  range.GetBaseAddress().Slide(vm_range.GetRangeBase());
+  range.SetByteSize(vm_range.GetByteSize());
+  return true;
 }
 
 AddressRanges Block::GetRanges() {
   AddressRanges ranges;
-  Function *function = CalculateSymbolContextFunction();
-  if (!function)
-    return ranges;
+  Function &function = GetFunction();
   for (size_t i = 0, e = m_ranges.GetSize(); i < e; ++i) {
     ranges.emplace_back();
     auto &range = ranges.back();
     const Range &vm_range = m_ranges.GetEntryRef(i);
-    range.GetBaseAddress() = function->GetAddress();
+    range.GetBaseAddress() = function.GetAddress();
     range.GetBaseAddress().Slide(vm_range.GetRangeBase());
     range.SetByteSize(vm_range.GetByteSize());
   }
@@ -316,13 +313,10 @@ bool Block::GetStartAddress(Address &addr) {
   if (m_ranges.IsEmpty())
     return false;
 
-  Function *function = CalculateSymbolContextFunction();
-  if (function) {
-    addr = function->GetAddress();
-    addr.Slide(m_ranges.GetEntryRef(0).GetRangeBase());
-    return true;
-  }
-  return false;
+  Function &function = GetFunction();
+  addr = function.GetAddress();
+  addr.Slide(m_ranges.GetEntryRef(0).GetRangeBase());
+  return true;
 }
 
 void Block::FinalizeRanges() {
@@ -336,11 +330,11 @@ void Block::AddRange(const Range &range) {
     Log *log = GetLog(LLDBLog::Symbols);
     if (log) {
       ModuleSP module_sp(m_parent_scope.CalculateSymbolContextModule());
-      Function *function = m_parent_scope.CalculateSymbolContextFunction();
-      const addr_t function_file_addr = function->GetAddress().GetFileAddress();
+      Function &function = GetFunction();
+      const addr_t function_file_addr = function.GetAddress().GetFileAddress();
       const addr_t block_start_addr = function_file_addr + range.GetRangeBase();
       const addr_t block_end_addr = function_file_addr + range.GetRangeEnd();
-      Type *func_type = function->GetType();
+      Type *func_type = function.GetType();
 
       const Declaration &func_decl = func_type->GetDeclaration();
       if (func_decl.GetLine()) {
@@ -351,7 +345,7 @@ void Block::AddRange(const Range &range) {
                   "} in function {0x%8.8" PRIx64 "} from %s",
                   func_decl.GetFile().GetPath().c_str(), func_decl.GetLine(),
                   GetID(), (uint32_t)m_ranges.GetSize(), block_start_addr,
-                  block_end_addr, parent_block->GetID(), function->GetID(),
+                  block_end_addr, parent_block->GetID(), function.GetID(),
                   module_sp->GetFileSpec().GetPath().c_str());
       } else {
         LLDB_LOGF(log,
@@ -360,7 +354,7 @@ void Block::AddRange(const Range &range) {
                   ") which is not contained in parent block {0x%8.8" PRIx64
                   "} in function {0x%8.8" PRIx64 "} from %s",
                   GetID(), (uint32_t)m_ranges.GetSize(), block_start_addr,
-                  block_end_addr, parent_block->GetID(), function->GetID(),
+                  block_end_addr, parent_block->GetID(), function.GetID(),
                   module_sp->GetFileSpec().GetPath().c_str());
       }
     }