while detects simple constant condition

1 files changed, 42 insertions, 19 deletions

diff --git a/src/codegen.cpp b/src/codegen.cpp
index 3e555a5778..3f4262364e 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -1157,29 +1157,52 @@ static LLVMValueRef gen_while_expr(CodeGen *g, AstNode *node) {
     assert(node->data.while_expr.condition);
     assert(node->data.while_expr.body);
 
-    LLVMBasicBlockRef cond_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileCond");
-    LLVMBasicBlockRef body_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileBody");
-    LLVMBasicBlockRef end_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileEnd");
+    if (get_expr_type(node)->id == TypeTableEntryIdUnreachable) {
+        // generate a forever loop. guarantees no break statements
 
-    add_debug_source_node(g, node);
-    LLVMBuildBr(g->builder, cond_block);
-
-    LLVMPositionBuilderAtEnd(g->builder, cond_block);
-    LLVMValueRef cond_val = gen_expr(g, node->data.while_expr.condition);
-    add_debug_source_node(g, node->data.while_expr.condition);
-    LLVMBuildCondBr(g->builder, cond_val, body_block, end_block);
-
-    LLVMPositionBuilderAtEnd(g->builder, body_block);
-    g->break_block_stack.append(end_block);
-    g->continue_block_stack.append(cond_block);
-    gen_expr(g, node->data.while_expr.body);
-    g->break_block_stack.pop();
-    g->continue_block_stack.pop();
-    if (get_expr_type(node->data.while_expr.body)->id != TypeTableEntryIdUnreachable) {
+        LLVMBasicBlockRef body_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileBody");
+
+        add_debug_source_node(g, node);
+        LLVMBuildBr(g->builder, body_block);
+
+        LLVMPositionBuilderAtEnd(g->builder, body_block);
+        g->continue_block_stack.append(body_block);
+        gen_expr(g, node->data.while_expr.body);
+        g->continue_block_stack.pop();
+
+        if (get_expr_type(node->data.while_expr.body)->id != TypeTableEntryIdUnreachable) {
+            add_debug_source_node(g, node);
+            LLVMBuildBr(g->builder, body_block);
+        }
+    } else {
+        // generate a normal while loop
+
+        LLVMBasicBlockRef cond_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileCond");
+        LLVMBasicBlockRef body_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileBody");
+        LLVMBasicBlockRef end_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "WhileEnd");
+
+        add_debug_source_node(g, node);
         LLVMBuildBr(g->builder, cond_block);
+
+        LLVMPositionBuilderAtEnd(g->builder, cond_block);
+        LLVMValueRef cond_val = gen_expr(g, node->data.while_expr.condition);
+        add_debug_source_node(g, node->data.while_expr.condition);
+        LLVMBuildCondBr(g->builder, cond_val, body_block, end_block);
+
+        LLVMPositionBuilderAtEnd(g->builder, body_block);
+        g->break_block_stack.append(end_block);
+        g->continue_block_stack.append(cond_block);
+        gen_expr(g, node->data.while_expr.body);
+        g->break_block_stack.pop();
+        g->continue_block_stack.pop();
+        if (get_expr_type(node->data.while_expr.body)->id != TypeTableEntryIdUnreachable) {
+            add_debug_source_node(g, node);
+            LLVMBuildBr(g->builder, cond_block);
+        }
+
+        LLVMPositionBuilderAtEnd(g->builder, end_block);
     }
 
-    LLVMPositionBuilderAtEnd(g->builder, end_block);
     return nullptr;
 }