From 71156924c6e2093690baabcb6e3120dd76ea58e3 Mon Sep 17 00:00:00 2001
From: Chris Cromer <chris@cromer.cl>
Date: Mon, 21 Nov 2022 21:24:44 -0300
Subject: [PATCH] add IR code generation to the AST

---
 src/ast/ast.h                       | 20 +++++++++++++++
 src/ast/call_expression_ast.cpp     | 31 +++++++++++++++++++++++
 src/ast/call_expression_ast.h       |  2 ++
 src/ast/error.cpp                   | 13 ++++++++++
 src/ast/error.h                     | 14 +++++++++++
 src/ast/expression_ast.h            |  5 +++-
 src/ast/function_ast.cpp            | 39 +++++++++++++++++++++++++++++
 src/ast/function_ast.h              |  2 ++
 src/ast/meson.build                 | 12 ++++-----
 src/ast/number_expression_ast.cpp   |  7 ++++++
 src/ast/number_expression_ast.h     |  2 ++
 src/ast/prototype_ast.cpp           | 25 ++++++++++++++++++
 src/ast/prototype_ast.h             |  4 +++
 src/ast/variable_expression_ast.cpp | 13 ++++++++++
 src/ast/variable_expression_ast.h   |  2 ++
 src/meson.build                     |  8 ++++++
 16 files changed, 192 insertions(+), 7 deletions(-)
 create mode 100644 src/ast/ast.h
 create mode 100644 src/ast/call_expression_ast.cpp
 create mode 100644 src/ast/error.cpp
 create mode 100644 src/ast/error.h
 create mode 100644 src/ast/function_ast.cpp
 create mode 100644 src/ast/number_expression_ast.cpp
 create mode 100644 src/ast/prototype_ast.cpp
 create mode 100644 src/ast/variable_expression_ast.cpp

diff --git a/src/ast/ast.h b/src/ast/ast.h
new file mode 100644
index 0000000..1002ace
--- /dev/null
+++ b/src/ast/ast.h
@@ -0,0 +1,20 @@
+#ifndef OBELISK_AST_AST_H
+#define OBELISK_AST_AST_H
+
+#include <llvm/IR/IRBuilder.h>
+#include <llvm/IR/LLVMContext.h>
+#include <llvm/IR/Module.h>
+#include <llvm/IR/Type.h>
+
+#include <map>
+#include <memory>
+
+namespace obelisk
+{
+    static std::unique_ptr<llvm::LLVMContext> TheContext;
+    static std::unique_ptr<llvm::Module> TheModule;
+    static std::unique_ptr<llvm::IRBuilder<>> Builder;
+    static std::map<std::string, llvm::Value *> NamedValues;
+} // namespace obelisk
+
+#endif
diff --git a/src/ast/call_expression_ast.cpp b/src/ast/call_expression_ast.cpp
new file mode 100644
index 0000000..eca1830
--- /dev/null
+++ b/src/ast/call_expression_ast.cpp
@@ -0,0 +1,31 @@
+#include "ast/ast.h"
+#include "ast/call_expression_ast.h"
+#include "ast/error.h"
+
+llvm::Value *obelisk::CallExpressionAST::codegen()
+{
+    // Look up the name in the global module table.
+    llvm::Function *calleeF = TheModule->getFunction(callee_);
+    if (!calleeF)
+    {
+        return LogErrorV("Unknown function referenced");
+    }
+
+    // If argument mismatch error.
+    if (calleeF->arg_size() != args_.size())
+    {
+        return LogErrorV("Incorrect # arguments passed");
+    }
+
+    std::vector<llvm::Value *> argsV;
+    for (unsigned i = 0, e = args_.size(); i != e; ++i)
+    {
+        argsV.push_back(args_[i]->codegen());
+        if (!argsV.back())
+        {
+            return nullptr;
+        }
+    }
+
+    return Builder->CreateCall(calleeF, argsV, "calltmp");
+}
diff --git a/src/ast/call_expression_ast.h b/src/ast/call_expression_ast.h
index 247e0fb..7deaea9 100644
--- a/src/ast/call_expression_ast.h
+++ b/src/ast/call_expression_ast.h
@@ -28,6 +28,8 @@ namespace obelisk
                 args_(std::move(args))
             {
             }
+
+            llvm::Value *codegen() override;
     };
 } // namespace obelisk
 
diff --git a/src/ast/error.cpp b/src/ast/error.cpp
new file mode 100644
index 0000000..779f794
--- /dev/null
+++ b/src/ast/error.cpp
@@ -0,0 +1,13 @@
+#include "ast/error.h"
+
+std::unique_ptr<obelisk::ExpressionAST> obelisk::LogError(const char *Str)
+{
+    fprintf(stderr, "Error: %s\n", Str);
+    return nullptr;
+}
+
+llvm::Value *obelisk::LogErrorV(const char *Str)
+{
+    LogError(Str);
+    return nullptr;
+}
diff --git a/src/ast/error.h b/src/ast/error.h
new file mode 100644
index 0000000..1770f7f
--- /dev/null
+++ b/src/ast/error.h
@@ -0,0 +1,14 @@
+#ifndef OBELISK_AST_ERROR_H
+#define OBELISK_AST_ERROR_H
+
+#include "ast/expression_ast.h"
+
+#include <memory>
+
+namespace obelisk
+{
+    std::unique_ptr<ExpressionAST> LogError(const char *Str);
+    llvm::Value *LogErrorV(const char *Str);
+} // namespace obelisk
+
+#endif
diff --git a/src/ast/expression_ast.h b/src/ast/expression_ast.h
index 11ba2d9..a77fff7 100644
--- a/src/ast/expression_ast.h
+++ b/src/ast/expression_ast.h
@@ -1,12 +1,15 @@
 #ifndef OBELISK_AST_EXPRESSION_AST_H
 #define OBELISK_AST_EXPRESSION_AST_H
 
+#include <llvm/IR/Constants.h>
+
 namespace obelisk
 {
     class ExpressionAST
     {
         public:
-            virtual ~ExpressionAST() = default;
+            virtual ~ExpressionAST()       = default;
+            virtual llvm::Value *codegen() = 0;
     };
 } // namespace obelisk
 
diff --git a/src/ast/function_ast.cpp b/src/ast/function_ast.cpp
new file mode 100644
index 0000000..1bdad9d
--- /dev/null
+++ b/src/ast/function_ast.cpp
@@ -0,0 +1,39 @@
+#include "ast/ast.h"
+#include "ast/function_ast.h"
+
+#include <llvm/IR/Verifier.h>
+
+llvm::Function *obelisk::FunctionAST::codegen()
+{
+    llvm::Function *theFunction = TheModule->getFunction(prototype_->getName());
+
+    if (!theFunction)
+    {
+        theFunction = prototype_->codegen();
+    }
+
+    if (!theFunction)
+    {
+        return nullptr;
+    }
+
+    llvm::BasicBlock *bB
+        = llvm::BasicBlock::Create(*TheContext, "entry", theFunction);
+    Builder->SetInsertPoint(bB);
+
+    NamedValues.clear();
+    for (auto &arg : theFunction->args())
+    {
+        NamedValues[std::string(arg.getName())] = &arg;
+    }
+
+    if (llvm::Value *retVal = body_->codegen())
+    {
+        Builder->CreateRet(retVal);
+        llvm::verifyFunction(*theFunction);
+        return theFunction;
+    }
+
+    theFunction->eraseFromParent();
+    return nullptr;
+}
diff --git a/src/ast/function_ast.h b/src/ast/function_ast.h
index 1d4ff4a..bdf630e 100644
--- a/src/ast/function_ast.h
+++ b/src/ast/function_ast.h
@@ -24,6 +24,8 @@ namespace obelisk
                 body_(std::move(body))
             {
             }
+
+            llvm::Function *codegen();
     };
 } // namespace obelisk
 
diff --git a/src/ast/meson.build b/src/ast/meson.build
index afb5a71..82aa247 100644
--- a/src/ast/meson.build
+++ b/src/ast/meson.build
@@ -1,8 +1,8 @@
 obelisk_ast_sources = files(
-    'call_expression_ast.h',
-    'expression_ast.h',
-    'function_ast.h',
-    'number_expression_ast.h',
-    'prototype_ast.h',
-    'variable_expression_ast.h'
+    'call_expression_ast.cpp',
+    'error.cpp',
+    'function_ast.cpp',
+    'number_expression_ast.cpp',
+    'prototype_ast.cpp',
+    'variable_expression_ast.cpp'
 )
diff --git a/src/ast/number_expression_ast.cpp b/src/ast/number_expression_ast.cpp
new file mode 100644
index 0000000..bff01cb
--- /dev/null
+++ b/src/ast/number_expression_ast.cpp
@@ -0,0 +1,7 @@
+#include "ast/ast.h"
+#include "ast/number_expression_ast.h"
+
+llvm::Value *obelisk::NumberExpressionAST::codegen()
+{
+    return llvm::ConstantFP::get(*TheContext, llvm::APFloat(number_));
+}
diff --git a/src/ast/number_expression_ast.h b/src/ast/number_expression_ast.h
index 568e2d6..874cb79 100644
--- a/src/ast/number_expression_ast.h
+++ b/src/ast/number_expression_ast.h
@@ -18,6 +18,8 @@ namespace obelisk
                 number_(number)
             {
             }
+
+            llvm::Value *codegen() override;
     };
 } // namespace obelisk
 
diff --git a/src/ast/prototype_ast.cpp b/src/ast/prototype_ast.cpp
new file mode 100644
index 0000000..f7caba4
--- /dev/null
+++ b/src/ast/prototype_ast.cpp
@@ -0,0 +1,25 @@
+#include "ast/ast.h"
+#include "ast/prototype_ast.h"
+
+llvm::Function *obelisk::PrototypeAST::codegen()
+{
+    std::vector<llvm::Type *> doubles(args_.size(),
+        llvm::Type::getDoubleTy(*TheContext));
+    llvm::FunctionType *FT
+        = llvm::FunctionType::get(llvm::Type::getDoubleTy(*TheContext),
+            doubles,
+            false);
+
+    llvm::Function *F = llvm::Function::Create(FT,
+        llvm::Function::ExternalLinkage,
+        name_,
+        obelisk::TheModule.get());
+
+    unsigned idx = 0;
+    for (auto &arg : F->args())
+    {
+        arg.setName(args_[idx++]);
+    }
+
+    return F;
+}
diff --git a/src/ast/prototype_ast.h b/src/ast/prototype_ast.h
index c461fb8..5e09b8c 100644
--- a/src/ast/prototype_ast.h
+++ b/src/ast/prototype_ast.h
@@ -1,6 +1,8 @@
 #ifndef OBELISK_AST_PROTOTYPE_AST_H
 #define OBELISK_AST_PROTOTYPE_AST_H
 
+#include <llvm/IR/Function.h>
+
 #include <string>
 #include <vector>
 
@@ -28,6 +30,8 @@ namespace obelisk
             {
                 return name_;
             }
+
+            llvm::Function* codegen();
     };
 } //namespace obelisk
 
diff --git a/src/ast/variable_expression_ast.cpp b/src/ast/variable_expression_ast.cpp
new file mode 100644
index 0000000..8923fa3
--- /dev/null
+++ b/src/ast/variable_expression_ast.cpp
@@ -0,0 +1,13 @@
+#include "ast/ast.h"
+#include "ast/error.h"
+#include "ast/variable_expression_ast.h"
+
+llvm::Value *obelisk::VariableExpressionAST::codegen()
+{
+    llvm::Value *V = NamedValues[name_];
+    if (!V)
+    {
+        return obelisk::LogErrorV("Unknown variable name");
+    }
+    return V;
+}
diff --git a/src/ast/variable_expression_ast.h b/src/ast/variable_expression_ast.h
index 6089080..3b51f87 100644
--- a/src/ast/variable_expression_ast.h
+++ b/src/ast/variable_expression_ast.h
@@ -19,6 +19,8 @@ namespace obelisk
                 name_(name)
             {
             }
+
+            llvm::Value *codegen() override;
     };
 } //namespace obelisk
 
diff --git a/src/meson.build b/src/meson.build
index 0474fe3..0f4d7b2 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -13,8 +13,16 @@ obelisk_sources += obelisk_ast_sources
 subdir('models')
 obelisk_sources += obelisk_model_sources
 
+r = run_command('llvm-config', '--cppflags', check : true)
+cpp_args = ' ' + r.stdout().replace('\n', ' ').replace('-I', '-isystem')
+
+r = run_command('llvm-config', '--ldflags', '--system-libs', '--libs', 'core', check : true)
+link_args = ' ' + r.stdout().replace('\n', ' ')
+
 executable('obelisk',
     obelisk_sources,
     dependencies : [sqlite3],
+    cpp_args : cpp_args.split(),
+    link_args : link_args.split(),
     install : true
 )