Prepare for ep 12

builder

@@ -26,6 +26,7 @@ export CCACHE_SLOPPINESS="pch_defines,time_macros"
 export ASAN_OPTIONS=check_initialization_order=1
 LSAN_OPTIONS=suppressions=$(pwd)/.ignore_sanitize
 export LSAN_OPTIONS
+export LDFLAGS="-fuse-ld=lld"
 
 # The `builder` script is supposed to be run from the
 # root of the source tree
@@ -103,15 +104,11 @@ function clean() {
 }
 
 function run() {
-    pushed_build
     LD_PRELOAD=$(clang -print-file-name=libclang_rt.asan-x86_64.so) "$BUILD_DIR"/src/serenec/serenec "$@"
-    popd_build
 }
 
 function repl() {
-    pushed_build
     LD_PRELOAD=$(clang -print-file-name=libclang_rt.asan-x86_64.so) "$BUILD_DIR"/src/serene-repl/serene-repl "$@"
-    popd_build
 }
 
 function memcheck() {

docs/videos.org

@@ -494,7 +494,8 @@ Source code -> IR X -> IR Y -> IR Z -> ... -> Target Code
    }
 #+END_SRC
 
-* Episode 11 - Lowering SLIR
+* DONE Episode 11 - Lowering SLIR
+CLOSED: [2021-11-01 Mon 15:14]
 ** Overview
 - What is a Pass?
 - Pass Manager
@@ -508,3 +509,52 @@ This framework allows for transforming a set of illegal operations to a set of l
 *** Rewrite Patterns
 *** Type Converter
 ** Full vs Partial Conversion
+* Episode 12 - Target code generation
+** Updates:
+*** JIT work
+*** Emacs dev mode
+** So far....
+** Next Step
+*** Compile to object files
+*** Link object files to create an executable
+** What is an object file?
+*** Symbols
+- A pair of a name and a value
+- Value of a *defined symbol* is an offset in the =Content=
+- *undefined symbols*
+*** Relocations
+Are computation to perform on the =Content=. For example, "set
+this location in the contents to the value of this symbol plus this addend".
+
+Linker will apply all the *relocations* in an object file on link time and if
+it can not resolve an undefined symbol most of the time it will raise an
+error (depending on the relocation and the symbol).
+
+*** Contents
+- Are what memory should look like during the execution
+- Have a size
+- Have a type
+- Have an array of bytes
+- Has sections like:
+  + .text: The target code generated by the compiler
+  + .data: The values of initialized variables
+  + .rdata: Static unnamed data like literal strings, protocol tables and ....
+  + .bss: Uninitialized variables (the content can be omitted or striped and assume
+    to contain only zeros)
+** Linking process
+During the linking process, linker assigns an address to each *defined* symbol
+and tries to =resolve= *undefined* symbols
+*** Linker will
+- reads the object files
+- reads the contents
+  + as raw data
+  + figures out the length
+  + reads the symbols and create a symbol table
+  + link undefined symbols to their definitions (possibly from other obj fils or libs)
+  + decide where all the content should go in the memory
+  + sort them based on the *type*
+  + concat them together
+  + apply relocations
+  + write the result to a file as an executable
+** AOT vs JIT
+** Let's look at some code

src/serenec/serenec.cpp

@@ -85,7 +85,7 @@ static cl::opt<std::string> outputFile(
 
 static cl::opt<std::string>
     outputDir("b", cl::desc("The absolute path to the build directory"),
-              cl::value_desc("filename"), cl::Required);
+              cl::value_desc("dir"), cl::Required);
 
 static cl::opt<enum Action> emitAction(
     "emit", cl::desc("Select what to dump."), cl::init(Compile),
@@ -159,6 +159,7 @@ int dumpAsObject(Namespace &ns) {
   llvm::raw_fd_ostream dest(destObjFilePath, ec, llvm::sys::fs::OF_None);
 
   if (ec) {
+    llvm::errs() << "Could not open file: " << destObjFilePath;
     llvm::errs() << "Could not open file: " << ec.message();
     return 1;
   }
@@ -189,24 +190,26 @@ int dumpAsObject(Namespace &ns) {
     args.push_back("-o");
     args.push_back(destFile.c_str());
 
-    d.setCheckInputsExist(false);
+    d.setCheckInputsExist(true);
 
     std::unique_ptr<clang::driver::Compilation> compilation;
     compilation.reset(d.BuildCompilation(args));
 
     if (!compilation) {
+      llvm::errs() << "can't create the compilation!\n";
       return 1;
     }
 
     llvm::SmallVector<std::pair<int, const clang::driver::Command *>>
         failCommand;
-    // compilation->ExecuteJobs(compilation->getJobs(), failCommand);
 
     d.ExecuteCompilation(*compilation, failCommand);
+
     if (failCommand.empty()) {
       llvm::outs() << "Done!\n";
     } else {
       llvm::errs() << "Linking failed!\n";
+      failCommand.front().second->Print(llvm::errs(), "\n", false);
     }
   }
 
@@ -228,7 +231,7 @@ int main(int argc, char *argv[]) {
   //       default to the current working dir
   if (outputDir == "-") {
     llvm::errs() << "Error: The build directory is not set. Did you forget to "
-                    "use '-build-dir'?\n";
+                    "use '-b'?\n";
     return 1;
   }