Save and restore previous exception handler when rethrowing

2 files changed, 22 insertions, 7 deletions

diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGenLocalVariableSpace.java b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGenLocalVariableSpace.java
index 2bd93582..c48e0667 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGenLocalVariableSpace.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGenLocalVariableSpace.java
@@ -32,6 +32,7 @@ public enum LlvmCodeGenLocalVariableSpace {
     SWITCH_DEFAULT_START("switchDefaultStart"),
     SWITCH_DEFAULT_END("switchDefaultEnd"),
     SWITCH_END("switchEnd"),
+    TRY_PREVIOUS_EXCEPTION_HANDLER("tryPreviousExceptionHandler"),
     TRY_BODY_START("tryBodyStart"),
     TRY_BODY_END("tryBodyEnd"),
     TRY_CATCH_START("tryCatchStart"),
diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmPatioCodeGen.java b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmPatioCodeGen.java
index 2f1ce44b..aa209fb4 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmPatioCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmPatioCodeGen.java
@@ -688,22 +688,31 @@ public class LlvmPatioCodeGen {
                     JMP_BUF_DATA
                 ));
 
-                var setjmpValueResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.SETJMP_VALUE);
-                var setjmpValue = setjmpValueResult.value;
-                context = setjmpValueResult.context;
+                var previousExceptionHandlerResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.TRY_PREVIOUS_EXCEPTION_HANDLER);
+                var previousExceptionHandler = previousExceptionHandlerResult.value;
+                context = previousExceptionHandlerResult.context;
 
-                context = context.addInstruction(SETJMP_DECLARATION.call(
-                    Optional.of(setjmpValue),
-                    List.of(jmpBuf)
+                context = context.addInstruction(new LlvmLoad(
+                    previousExceptionHandler,
+                    LlvmTypes.pointer(LlvmTypes.VOID),
+                    new LlvmVariableGlobal(EXCEPTION_HANDLER_DECLARATION.name())
                 ));
 
-                // TODO: save and restore previous exception handler
                 context = context.addInstruction(new LlvmStore(
                     LlvmTypes.pointer(LlvmTypes.VOID),
                     jmpBuf,
                     new LlvmVariableGlobal(EXCEPTION_HANDLER_DECLARATION.name())
                 ));
 
+                var setjmpValueResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.SETJMP_VALUE);
+                var setjmpValue = setjmpValueResult.value;
+                context = setjmpValueResult.context;
+
+                context = context.addInstruction(SETJMP_DECLARATION.call(
+                    Optional.of(setjmpValue),
+                    List.of(jmpBuf)
+                ));
+
                 context = context.addTerminatorInstruction(new LlvmSwitch(
                     LlvmTypes.INT_32,
                     setjmpValue,
@@ -712,6 +721,11 @@ public class LlvmPatioCodeGen {
                 ));
 
                 context = context.startBasicBlock(rethrowStartLabel);
+                context = context.addInstruction(new LlvmStore(
+                    LlvmTypes.pointer(LlvmTypes.VOID),
+                    previousExceptionHandler,
+                    new LlvmVariableGlobal(EXCEPTION_HANDLER_DECLARATION.name())
+                ));
                 context = context.addInstruction(RETHROW_DECLARATION.call(
                     Optional.empty(),
                     List.of(setjmpValue)