Implement if-else in wasm_to_x86 backend

integration_tests/if_01.py

@@ -0,0 +1,59 @@
+def Test_if_01():
+    if True:
+        print(1)
+
+    if False:
+        print(0)
+
+    if 1 < 0:
+        print(0)
+    else:
+        print(1)
+
+    if 1 > 0:
+        print(1)
+    else:
+        print(0)
+
+    if 1 < 0:
+        print(1)
+    elif 1 > 0:
+        print(1)
+    else:
+        print(0)
+
+def Test_if_02():
+    if True:
+        print(1)
+        if True:
+            print(2)
+            if False:
+                print(3)
+            elif True:
+                print(4)
+            else:
+                print(5)
+        else:
+            print(6)
+
+    if True:
+        print(7)
+        if False:
+            print(8)
+            if False:
+                print(9)
+            else:
+                print(10)
+        else:
+            if True:
+                print(11)
+            else:
+                print(12)
+            print(13)
+    print(14)
+
+def Verify():
+    Test_if_01()
+    Test_if_02()
+
+Verify()

src/bin/lpython.cpp

@@ -775,7 +775,7 @@ int compile_to_binary_x86(
 
     // ASR -> X86
     auto asr_to_x86_start = std::chrono::high_resolution_clock::now();
-    LFortran::Result<int> r3 = LFortran::asr_to_x86(*asr, al, outfile, time_report);
+    LFortran::Result<int> r3 = LFortran::asr_to_x86(*asr, al, outfile, time_report, diagnostics);
     auto asr_to_x86_end = std::chrono::high_resolution_clock::now();
     times.push_back(std::make_pair("ASR to X86", std::chrono::duration<double, std::milli>(asr_to_x86_end - asr_to_x86_start).count()));
     std::cerr << diagnostics.render(input, lm, compiler_options);

src/libasr/codegen/asr_to_wasm.cpp

@@ -2048,11 +2048,9 @@ class ASRToWASMVisitor : public ASR::BaseVisitor<ASRToWASMVisitor> {
         for (size_t i = 0; i < x.n_body; i++) {
             this->visit_stmt(*x.m_body[i]);
         }
-        if (x.n_orelse) {
-            wasm::emit_b8(m_code_section, m_al, 0x05);  // starting of else
-            for (size_t i = 0; i < x.n_orelse; i++) {
-                this->visit_stmt(*x.m_orelse[i]);
-            }
+        wasm::emit_b8(m_code_section, m_al, 0x05);  // starting of else
+        for (size_t i = 0; i < x.n_orelse; i++) {
+            this->visit_stmt(*x.m_orelse[i]);
         }
         nesting_level--;
         wasm::emit_expr_end(m_code_section, m_al);  // emit if end
@@ -2119,6 +2117,7 @@ class ASRToWASMVisitor : public ASR::BaseVisitor<ASRToWASMVisitor> {
         }
         wasm::emit_i32_const(m_code_section, m_al, 1);  // non-zero exit code
         exit();
+        wasm::emit_b8(m_code_section, m_al, 0x05);  // starting of else
         wasm::emit_expr_end(m_code_section, m_al);  // emit if end
     }
 };

src/libasr/codegen/asr_to_x86.cpp

@@ -526,7 +526,8 @@ class ASRToX86Visitor : public ASR::BaseVisitor<ASRToX86Visitor>
 
 
 Result<int> asr_to_x86(ASR::TranslationUnit_t &asr, Allocator &al,
-        const std::string &filename, bool time_report)
+        const std::string &filename, bool time_report,
+        diag::Diagnostics &diagnostics)
 {
     int time_pass_global=0;
     int time_pass_do_loops=0;
@@ -558,8 +559,8 @@ Result<int> asr_to_x86(ASR::TranslationUnit_t &asr, Allocator &al,
         try {
             v.visit_asr((ASR::asr_t &)asr);
         } catch (const CodeGenError &e) {
-            Error error;
-            return error;
+            diagnostics.diagnostics.push_back(e.d);
+            return Error();
         }
         auto t2 = std::chrono::high_resolution_clock::now();
         time_visit_asr = std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count();
@@ -579,6 +580,9 @@ Result<int> asr_to_x86(ASR::TranslationUnit_t &asr, Allocator &al,
         time_save = std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count();
     }
 
+    //! Helpful for debugging
+    // std::cout << v.m_a.get_asm() << std::endl;
+
     if (time_report) {
         std::cout << "Codegen Time report:" << std::endl;
         std::cout << "Global:     " << std::setw(5) << time_pass_global << std::endl;

src/libasr/codegen/asr_to_x86.h

@@ -7,7 +7,8 @@ namespace LFortran {
 
     // Generates a 32-bit x86 Linux executable binary `filename`
     Result<int> asr_to_x86(ASR::TranslationUnit_t &asr, Allocator &al,
-            const std::string &filename, bool time_report);
+            const std::string &filename, bool time_report,
+            diag::Diagnostics &diagnostics);
 
 } // namespace LFortran
 

src/libasr/codegen/wasm_to_x86.cpp

@@ -16,6 +16,7 @@ class X86Visitor : public WASMDecoder<X86Visitor>,
    public:
     X86Assembler &m_a;
     uint32_t cur_func_idx;
+    std::vector<uint32_t> unique_id;
 
     X86Visitor(X86Assembler &m_a, Allocator &al,
                diag::Diagnostics &diagonostics, Vec<uint8_t> &code)
@@ -68,6 +69,27 @@ class X86Visitor : public WASMDecoder<X86Visitor>,
         }
     }
 
+    void visit_EmtpyBlockType() {}
+
+    void visit_If() {
+        unique_id.push_back(offset);
+        m_a.asm_pop_r32(X86Reg::eax);
+        m_a.asm_cmp_r32_imm8(LFortran::X86Reg::eax, 1);
+        m_a.asm_je_label(".then_" + std::to_string(unique_id.back()));
+        m_a.asm_jmp_label(".else_" + std::to_string(unique_id.back()));
+        m_a.add_label(".then_" + std::to_string(unique_id.back()));
+        {
+            decode_instructions();
+        }
+        m_a.add_label(".endif_" + std::to_string(unique_id.back()));
+        unique_id.pop_back();
+    }
+
+    void visit_Else() {
+        m_a.asm_jmp_label(".endif_" + std::to_string(unique_id.back()));
+        m_a.add_label(".else_" + std::to_string(unique_id.back()));
+    }
+
     void visit_LocalGet(uint32_t localidx) {
         X86Reg base = X86Reg::ebp;
         int no_of_params =
@@ -230,6 +252,9 @@ Result<int> wasm_to_x86(Vec<uint8_t> &wasm_bytes, Allocator &al,
                 .count();
     }
 
+    //! Helpful for debugging
+    // std::cout << x86_visitor.m_a.get_asm() << std::endl;
+
     if (time_report) {
         std::cout << "Codegen Time report:" << std::endl;
         std::cout << "Decode wasm: " << std::setw(5) << time_decode_wasm

tests/reference/wat-loop1-e0046d4.json

@@ -6,7 +6,7 @@
     "outfile": null,
     "outfile_hash": null,
     "stdout": "wat-loop1-e0046d4.stdout",
-    "stdout_hash": "12b741cf8600fa79f42d342a3fd339bc84963713fd1257d6d4b4141b",
+    "stdout_hash": "f6dfe3c647ade9c3166a32025fac278f4ab5b6e04fea7f2192fb4ce7",
     "stderr": null,
     "stderr_hash": null,
     "returncode": 0

tests/reference/wat-loop1-e0046d4.stdout

@@ -48,6 +48,7 @@
             local.set 1
             local.get 1
             return
+        else
         end
         i32.const 1
         local.set 2
@@ -119,6 +120,7 @@
             local.set 1
             local.get 1
             return
+        else
         end
         i64.const 1
         local.set 2