[solidity] Add CLI option '-g' to generate debug information.

Add command line option '-g' to generate source level debug information
in the output code. This only works with the LLVM-IR code generator.

Add flag 'emit_debug_info' to the llvm-context optimizer/code-gen
settings structure, to record the setting of the '-g' CLI option.

crates/llvm-context/src/optimizer/settings/mod.rs

@@ -9,7 +9,7 @@ use itertools::Itertools;
 
 use self::size_level::SizeLevel;
 
-/// The LLVM optimizer settings.
+/// The LLVM optimizer and code-gen settings.
 #[derive(Debug, Serialize, Deserialize, Clone, Eq)]
 pub struct Settings {
     /// The middle-end optimization level.
@@ -28,6 +28,9 @@ pub struct Settings {
     pub is_verify_each_enabled: bool,
     /// Whether the LLVM `debug logging` option is enabled.
     pub is_debug_logging_enabled: bool,
+
+    /// Whether to generate source-level debug information.
+    pub emit_debug_info: bool,
 }
 
 impl Settings {
@@ -47,6 +50,8 @@ impl Settings {
 
             is_verify_each_enabled: false,
             is_debug_logging_enabled: false,
+
+            emit_debug_info: false,
         }
     }
 
@@ -58,6 +63,8 @@ impl Settings {
 
         is_verify_each_enabled: bool,
         is_debug_logging_enabled: bool,
+
+        emit_debug_info: bool,
     ) -> Self {
         Self {
             level_middle_end,
@@ -69,6 +76,8 @@ impl Settings {
 
             is_verify_each_enabled,
             is_debug_logging_enabled,
+
+            emit_debug_info,
         }
     }
 
@@ -220,6 +229,11 @@ impl Settings {
     pub fn is_system_request_memoization_disabled(&self) -> bool {
         self.is_system_request_memoization_disabled
     }
+
+    /// Whether source-level debug information should be emitted.
+    pub fn emit_debug_info(&self) -> bool {
+        return self.emit_debug_info;
+    }
 }
 
 impl PartialEq for Settings {

crates/solidity/src/resolc/arguments.rs

@@ -149,6 +149,11 @@ pub struct Arguments {
     #[structopt(long = "suppress-warnings")]
     pub suppress_warnings: Option<Vec<String>>,
 
+    /// Generate source based debug information in the output code file. This only has an effect
+    /// with the LLVM-IR code generator and is ignored otherwise.
+    #[structopt(short = 'g')]
+    pub emit_source_debug_info: bool,
+
     /// Dump all IRs to files in the specified directory.
     /// Only for testing and debugging.
     #[structopt(long = "debug-output-dir")]

crates/solidity/src/resolc/main.rs

@@ -106,6 +106,7 @@ fn main_inner() -> anyhow::Result<()> {
     }
     optimizer_settings.is_verify_each_enabled = arguments.llvm_verify_each;
     optimizer_settings.is_debug_logging_enabled = arguments.llvm_debug_logging;
+    optimizer_settings.emit_debug_info = arguments.emit_source_debug_info;
 
     let include_metadata_hash = match arguments.metadata_hash {
         Some(metadata_hash) => {