Avoid silently dropping instructions when generating LLVM code

1 files changed, 54 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvmFunctionContextTests.java b/src/test/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvmFunctionContextTests.java
new file mode 100644
index 00000000..0ed0be80
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvmFunctionContextTests.java
@@ -0,0 +1,54 @@
+package org.shedlang.compiler.backends.llvm.codegen;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.backends.llvm.ir.ast.LlvmIr;
+import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmTypes;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.equalTo;
+import static org.zwobble.precisely.Matchers.isSequence;
+
+public class PatioToLlvmFunctionContextTests {
+    @Test
+    public void whenThereAreNoInstructionsOutsideOfBasicBlockThenToBasicBlocksReturnsBasicBlocks() {
+        var context = PatioToLlvmFunctionContext.of(PatioToLlvmModuleContext.EMPTY);
+        var addInstruction = LlvmIr.add(
+            LlvmIr.variableLocal("a"),
+            LlvmTypes.INT_64,
+            LlvmIr.variableLocal("b"),
+            LlvmIr.variableLocal("c")
+        );
+        context = context.addInstruction(addInstruction);
+        var branchInstruction = LlvmIr.brUnconditional("end");
+        context = context.addTerminatorInstruction(branchInstruction);
+
+        var basicBlocks = context.toBasicBlocks();
+
+        assertThat(basicBlocks.value(), isSequence(
+            equalTo(LlvmIr.basicBlock(List.of(addInstruction), branchInstruction))
+        ));
+    }
+
+    @Test
+    public void whenThereAreInstructionsOutsideOfBasicBlockThenToBasicBlocksThrowsException() {
+        var context = PatioToLlvmFunctionContext.of(PatioToLlvmModuleContext.EMPTY);
+        var addInstruction = LlvmIr.add(
+            LlvmIr.variableLocal("a"),
+            LlvmTypes.INT_64,
+            LlvmIr.variableLocal("b"),
+            LlvmIr.variableLocal("c")
+        );
+        context = context.addInstruction(addInstruction);
+
+        var c = context;
+        var error = assertThrows(
+            IllegalStateException.class,
+            () -> c.toBasicBlocks()
+        );
+
+        assertThat(error.getMessage(), equalTo("basic block is missing terminator instruction"));
+    }
+}