LLVMCodeAnalyzer: Fix previous else branch

Author: adazem009

src/engine/internal/llvm/llvmcodeanalyzer.cpp

@@ -38,12 +38,21 @@ void LLVMCodeAnalyzer::analyzeScript(const LLVMInstructionList &script) const
             branch->listTypes = currentBranch->listTypes;
             currentBranch = branch.get();
             branches.push_back(std::move(branch));
+
+            assert(!currentBranch->isAtElse);
         } else if (isElse(ins)) {
             assert(!currentBranch->elseBranch);
 
             // Enter else branch with type information from the previous branch
             Branch *previousBranch = branches[branches.size() - 2].get();
+
+            if (previousBranch->isAtElse) {
+                previousBranch = previousBranch->elseBranch.get();
+                assert(previousBranch);
+            }
+
             currentBranch->elseBranch = std::make_unique<Branch>();
+            currentBranch->isAtElse = true;
             currentBranch = currentBranch->elseBranch.get();
             currentBranch->start = ins;
             currentBranch->variableTypes = previousBranch->variableTypes;
@@ -57,9 +66,13 @@ void LLVMCodeAnalyzer::analyzeScript(const LLVMInstructionList &script) const
                 // Merge/override types
                 Branch *previousBranch = branches[branches.size() - 2].get();
                 Branch *primaryBranch = branches.back().get();
-
                 assert(primaryBranch);
 
+                if (previousBranch->isAtElse) {
+                    previousBranch = previousBranch->elseBranch.get();
+                    assert(previousBranch);
+                }
+
                 if (primaryBranch && primaryBranch->elseBranch) {
                     // The previous variable types can be ignored in if/else statements
                     overrideVariableTypes(primaryBranch, previousBranch);

src/engine/internal/llvm/llvmcodeanalyzer.h

@@ -29,6 +29,7 @@ class LLVMCodeAnalyzer
                 std::unordered_map<List *, Compiler::StaticType> listTypes;
 
                 std::unique_ptr<Branch> elseBranch;
+                bool isAtElse = false; // whether we're currently processing the else branch
         };
 
         void updateVariableType(Branch *branch, LLVMInstruction *ins, std::unordered_set<LLVMInstruction *> &typeAssignedInstructions, bool isWrite) const;

test/llvm/code_analyzer/variable_type_analysis.cpp

@@ -896,6 +896,47 @@ TEST_F(LLVMCodeAnalyzer_VariableTypeAnalysis, WriteInLoop)
     ASSERT_EQ(setVar->targetType, Compiler::StaticType::Unknown);
 }
 
+TEST_F(LLVMCodeAnalyzer_VariableTypeAnalysis, NestedIfStatements)
+{
+    LLVMInstructionList list;
+    Variable var("", "");
+
+    auto outerIf = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::BeginIf, false);
+    list.addInstruction(outerIf);
+
+    auto setVar1 = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::WriteVariable, false);
+    LLVMConstantRegister value1(Compiler::StaticType::Number, 1);
+    setVar1->targetVariable = &var;
+    setVar1->args.push_back({ Compiler::StaticType::Unknown, &value1 });
+    list.addInstruction(setVar1);
+
+    auto outerElse = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::BeginElse, false);
+    list.addInstruction(outerElse);
+
+    auto innerIf = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::BeginIf, false);
+    list.addInstruction(innerIf);
+
+    auto innerElse = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::BeginElse, false);
+    list.addInstruction(innerElse);
+
+    auto innerIfEnd = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::EndIf, false);
+    list.addInstruction(innerIfEnd);
+
+    auto setVar2 = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::WriteVariable, false);
+    LLVMConstantRegister value2(Compiler::StaticType::String, "test");
+    setVar2->targetVariable = &var;
+    setVar2->args.push_back({ Compiler::StaticType::Unknown, &value2 });
+    list.addInstruction(setVar2);
+
+    auto outerIfEnd = std::make_shared<LLVMInstruction>(LLVMInstruction::Type::EndIf, false);
+    list.addInstruction(outerIfEnd);
+
+    m_analyzer->analyzeScript(list);
+
+    ASSERT_EQ(setVar1->targetType, Compiler::StaticType::Unknown);
+    ASSERT_EQ(setVar2->targetType, Compiler::StaticType::Unknown);
+}
+
 TEST_F(LLVMCodeAnalyzer_VariableTypeAnalysis, ComplexNestedControlFlow)
 {
     LLVMInstructionList list;