linux: support VDSO for clock_gettime

also fix a compiler crash when using cmpxchg with nullable pointer

1 files changed, 10 insertions, 0 deletions

diff --git a/src/codegen.cpp b/src/codegen.cpp
index b5c8fdecac..4581c3e2b3 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -3561,6 +3561,16 @@ static LLVMValueRef ir_render_cmpxchg(CodeGen *g, IrExecutable *executable, IrIn
     LLVMValueRef result_val = ZigLLVMBuildCmpXchg(g->builder, ptr_val, cmp_val, new_val,
             success_order, failure_order, instruction->is_weak);
 
+    TypeTableEntry *maybe_type = instruction->base.value.type;
+    assert(maybe_type->id == TypeTableEntryIdMaybe);
+    TypeTableEntry *child_type = maybe_type->data.maybe.child_type;
+
+    if (type_is_codegen_pointer(child_type)) {
+        LLVMValueRef payload_val = LLVMBuildExtractValue(g->builder, result_val, 0, "");
+        LLVMValueRef success_bit = LLVMBuildExtractValue(g->builder, result_val, 1, "");
+        return LLVMBuildSelect(g->builder, success_bit, LLVMConstNull(child_type->type_ref), payload_val, "");
+    }
+
     assert(instruction->tmp_ptr != nullptr);
     assert(type_has_bits(instruction->type));