HackStudio: Implement "Step Over" debugging action

The "Step Over" action continues execution without stepping into
instructions in subsequent function calls.

4 files changed, 44 insertions, 4 deletions

diff --git a/Libraries/LibDebug/DebugInfo.cpp b/Libraries/LibDebug/DebugInfo.cpp
index cd46ab1c47..f8b13d25b5 100644
--- a/Libraries/LibDebug/DebugInfo.cpp
+++ b/Libraries/LibDebug/DebugInfo.cpp
@@ -138,7 +138,7 @@ Optional<DebugInfo::SourcePosition> DebugInfo::get_source_position(u32 target_ad
     // TODO: We can do a binray search here
     for (size_t i = 0; i < m_sorted_lines.size() - 1; ++i) {
         if (m_sorted_lines[i + 1].address > target_address) {
-            return Optional<SourcePosition>({ m_sorted_lines[i].file, m_sorted_lines[i].line, m_sorted_lines[i].address });
+            return SourcePosition::from_line_info(m_sorted_lines[i]);
         }
     }
     return {};
@@ -301,10 +301,37 @@ OwnPtr<DebugInfo::VariableInfo> DebugInfo::create_variable_info(const Dwarf::DIE
 
 String DebugInfo::name_of_containing_function(u32 address) const
 {
+    auto function = get_containing_function(address);
+    if (!function.has_value())
+        return {};
+    return function.value().name;
+}
+
+Optional<DebugInfo::VariablesScope> DebugInfo::get_containing_function(u32 address) const
+{
     for (const auto& scope : m_scopes) {
         if (!scope.is_function || address < scope.address_low || address >= scope.address_high)
             continue;
-        return scope.name;
+        return scope;
     }
     return {};
 }
+
+Vector<DebugInfo::SourcePosition> DebugInfo::source_lines_in_scope(const VariablesScope& scope) const
+{
+    Vector<DebugInfo::SourcePosition> source_lines;
+    for (const auto& line : m_sorted_lines) {
+        if (line.address < scope.address_low)
+            continue;
+
+        if (line.address >= scope.address_high)
+            break;
+        source_lines.append(SourcePosition::from_line_info(line));
+    }
+    return source_lines;
+}
+
+DebugInfo::SourcePosition DebugInfo::SourcePosition::from_line_info(const LineProgram::LineInfo& line)
+{
+    return { line.file, line.line, line.address };
+}
diff --git a/Libraries/LibDebug/DebugInfo.h b/Libraries/LibDebug/DebugInfo.h
index de9de2ddff..9208dea102 100644
--- a/Libraries/LibDebug/DebugInfo.h
+++ b/Libraries/LibDebug/DebugInfo.h
@@ -47,6 +47,8 @@ public:
 
         bool operator==(const SourcePosition& other) const { return file_path == other.file_path && line_number == other.line_number; }
         bool operator!=(const SourcePosition& other) const { return !(*this == other); }
+
+        static SourcePosition from_line_info(const LineProgram::LineInfo&);
     };
 
     struct VariableInfo {
@@ -80,7 +82,7 @@ public:
         bool is_function { false };
         String name;
         u32 address_low { 0 };
-        u32 address_high { 0 };
+        u32 address_high { 0 }; // Non-inclusive - the lowest address after address_low that's not in this scope
         Vector<Dwarf::DIE> dies_of_variables;
     };
 
@@ -104,6 +106,8 @@ public:
     }
 
     String name_of_containing_function(u32 address) const;
+    Vector<SourcePosition> source_lines_in_scope(const VariablesScope&) const;
+    Optional<VariablesScope> get_containing_function(u32 address) const;
 
 private:
     void prepare_variable_scopes();
diff --git a/Libraries/LibDebug/DebugSession.cpp b/Libraries/LibDebug/DebugSession.cpp
index 242108761a..2c6394de1e 100644
--- a/Libraries/LibDebug/DebugSession.cpp
+++ b/Libraries/LibDebug/DebugSession.cpp
@@ -175,6 +175,8 @@ bool DebugSession::enable_breakpoint(void* address)
     auto breakpoint = m_breakpoints.get(address);
     ASSERT(breakpoint.has_value());
 
+    ASSERT(breakpoint.value().state == BreakPointState::Disabled);
+
     if (!poke(reinterpret_cast<u32*>(breakpoint.value().address), (breakpoint.value().original_first_word & ~(uint32_t)0xff) | BREAKPOINT_INSTRUCTION))
         return false;
 
diff --git a/Libraries/LibDebug/DebugSession.h b/Libraries/LibDebug/DebugSession.h
index 84a87922c2..e11f93c944 100644
--- a/Libraries/LibDebug/DebugSession.h
+++ b/Libraries/LibDebug/DebugSession.h
@@ -207,10 +207,17 @@ void DebugSession::run(Callback callback)
 
         // Re-enable the breakpoint if it wasn't removed by the user
         if (current_breakpoint.has_value() && m_breakpoints.contains(current_breakpoint.value().address)) {
-            // The current breakpoint was removed in order to make it transparrent to the user.
+            // The current breakpoint was removed to make it transparrent to the user.
             // We now want to re-enable it - the code execution flow could hit it again.
             // To re-enable the breakpoint, we first perform a single step and execute the
             // instruction of the breakpoint, and then redo the INT3 patch in its first byte.
+
+            // If the user manually inserted a breakpoint at were we breaked at originally,
+            // we need to disable that breakpoint because we want to singlestep over it to execute the
+            // instruction we breaked on (we re-enable it again later anyways).
+            if (m_breakpoints.contains(current_breakpoint.value().address) && m_breakpoints.get(current_breakpoint.value().address).value().state == BreakPointState::Enabled) {
+                disable_breakpoint(current_breakpoint.value().address);
+            }
             auto stopped_address = single_step();
             enable_breakpoint(current_breakpoint.value().address);
             did_single_step = true;