From 8a44109f93559e9e9213be2fe376fe8df58997f6 Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Thu, 17 Sep 2020 18:33:52 -0700
Subject: [PATCH] Use an  instruction instead of a special-case boolean
 instruction.

---
 13/ast.cpp         | 11 ++++++++---
 13/instruction.cpp | 41 +++++------------------------------------
 13/instruction.hpp | 15 ++++-----------
 3 files changed, 17 insertions(+), 50 deletions(-)

diff --git a/13/ast.cpp b/13/ast.cpp
index 8fc5d78..57293e9 100644
--- a/13/ast.cpp
+++ b/13/ast.cpp
@@ -3,6 +3,7 @@
 #include <type_traits>
 #include "binop.hpp"
 #include "error.hpp"
+#include "instruction.hpp"
 #include "type.hpp"
 #include "type_env.hpp"
 #include "env.hpp"
@@ -308,9 +309,13 @@ struct case_strategy_bool {
             return;
         }
 
-        into.push_back(instruction_ptr(new instruction_if(
-                        std::move(ms.get_case_for(true)),
-                        std::move(ms.get_case_for(false)))));
+        instruction_ijump* ijump = new instruction_ijump();
+        instruction_ptr inst(ijump);
+        ijump->branches.push_back(std::move(ms.get_case_for(false)));
+        ijump->tag_mappings[0] = 0;
+        ijump->branches.push_back(std::move(ms.get_case_for(true)));
+        ijump->tag_mappings[1] = 1;
+        into.push_back(std::move(inst));
     }
 };
 
diff --git a/13/instruction.cpp b/13/instruction.cpp
index 7fd8c0c..4700688 100644
--- a/13/instruction.cpp
+++ b/13/instruction.cpp
@@ -100,7 +100,7 @@ void instruction_jump::print(int indent, std::ostream& to) const {
 
 void instruction_jump::gen_llvm(llvm_context& ctx, Function* f) const {
     auto top_node = ctx.create_peek(f, ctx.create_size(0));
-    auto tag = ctx.unwrap_data_tag(top_node);
+    auto tag = get_case_value(ctx, top_node);
     auto safety_block = ctx.create_basic_block("safety", f);
     auto switch_op = ctx.get_builder().CreateSwitch(tag, safety_block, tag_mappings.size());
     std::vector<BasicBlock*> blocks;
@@ -122,43 +122,12 @@ void instruction_jump::gen_llvm(llvm_context& ctx, Function* f) const {
     ctx.get_builder().SetInsertPoint(safety_block);
 }
 
-void instruction_if::print(int indent, std::ostream& to) const {
-    print_indent(indent, to);
-    to << "If(" << std::endl;
-    for(auto& instruction : on_true) {
-        instruction->print(indent + 2, to);
-    }
-    to << std::endl;
-    for(auto& instruction : on_false) {
-        instruction->print(indent + 2, to);
-    }
-    print_indent(indent, to);
-    to << ")" << std::endl;
+Value* instruction_jump::get_case_value(llvm_context& ctx, Value* v) const {
+    return ctx.unwrap_data_tag(v);
 }
 
-void instruction_if::gen_llvm(llvm_context& ctx, llvm::Function* f) const {
-    auto top_node = ctx.create_peek(f, ctx.create_size(0));
-    auto num = ctx.unwrap_num(top_node);
-
-    auto nonzero_block = ctx.create_basic_block("nonzero", f);
-    auto zero_block = ctx.create_basic_block("zero", f);
-    auto resume_block = ctx.create_basic_block("resume", f);
-    auto switch_op = ctx.get_builder().CreateSwitch(num, nonzero_block, 2);
-
-    switch_op->addCase(ctx.create_i32(0), zero_block);
-    ctx.get_builder().SetInsertPoint(nonzero_block);
-    for(auto& instruction : on_true) {
-        instruction->gen_llvm(ctx, f);
-    }
-    ctx.get_builder().CreateBr(resume_block);
-
-    ctx.get_builder().SetInsertPoint(zero_block);
-    for(auto& instruction : on_false) {
-        instruction->gen_llvm(ctx, f);
-    }
-    ctx.get_builder().CreateBr(resume_block);
-
-    ctx.get_builder().SetInsertPoint(resume_block);
+Value* instruction_ijump::get_case_value(llvm_context& ctx, Value* v) const {
+    return ctx.unwrap_num(v);
 }
 
 void instruction_slide::print(int indent, std::ostream& to) const {
diff --git a/13/instruction.hpp b/13/instruction.hpp
index 36b4191..15639ed 100644
--- a/13/instruction.hpp
+++ b/13/instruction.hpp
@@ -99,19 +99,12 @@ struct instruction_jump : public instruction {
 
     void print(int indent, std::ostream& to) const;
     void gen_llvm(llvm_context& ctx, llvm::Function* f) const;
+
+    virtual llvm::Value* get_case_value(llvm_context& ctx, llvm::Value*) const;
 };
 
-struct instruction_if : public instruction {
-    std::vector<instruction_ptr> on_true;
-    std::vector<instruction_ptr> on_false;
-
-    instruction_if(
-            std::vector<instruction_ptr> t,
-            std::vector<instruction_ptr> f)
-        : on_true(std::move(t)), on_false(std::move(f)) {}
-
-    void print(int indent, std::ostream& to) const;
-    void gen_llvm(llvm_context& ctx, llvm::Function* f) const;
+struct instruction_ijump : public instruction_jump {
+    llvm::Value* get_case_value(llvm_context& ctx, llvm::Value*) const;
 };
 
 struct instruction_slide : public instruction {