stage2: optimize size of optional slices

2 files changed, 17 insertions, 7 deletions

diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index d6584d75ae..5f6f2fd6d5 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -726,7 +726,11 @@ pub const DeclGen = struct {
                 }
 
                 if (ty.optionalReprIsPayload()) {
-                    return dg.renderValue(writer, payload_ty, val, location);
+                    if (val.castTag(.opt_payload)) |payload| {
+                        return dg.renderValue(writer, payload_ty, payload.data, location);
+                    } else {
+                        return dg.renderValue(writer, payload_ty, val, location);
+                    }
                 }
 
                 try writer.writeByte('(');
@@ -3263,11 +3267,9 @@ fn airIsNull(
     try f.writeCValue(writer, operand);
 
     const ty = f.air.typeOf(un_op);
+    const opt_ty = if (deref_suffix[0] != 0) ty.childType() else ty;
     var opt_buf: Type.Payload.ElemType = undefined;
-    const payload_ty = if (deref_suffix[0] != 0)
-        ty.childType().optionalChild(&opt_buf)
-    else
-        ty.optionalChild(&opt_buf);
+    const payload_ty = opt_ty.optionalChild(&opt_buf);
 
     if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
         try writer.print("){s} {s} true;\n", .{ deref_suffix, operator });
@@ -3276,6 +3278,8 @@ fn airIsNull(
         try writer.print("){s} {s} NULL;\n", .{ deref_suffix, operator });
     } else if (payload_ty.zigTypeTag() == .ErrorSet) {
         try writer.print("){s} {s} 0;\n", .{ deref_suffix, operator });
+    } else if (payload_ty.isSlice() and opt_ty.optionalReprIsPayload()) {
+        try writer.print("){s}.ptr {s} NULL;\n", .{ deref_suffix, operator });
     } else {
         try writer.print("){s}.is_null {s} true;\n", .{ deref_suffix, operator });
     }
diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index ffc19cb6f6..d4a94d1308 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -6316,18 +6316,24 @@ pub const FuncGen = struct {
         const operand_ty = self.air.typeOf(un_op);
         const optional_ty = if (operand_is_ptr) operand_ty.childType() else operand_ty;
         const optional_llvm_ty = try self.dg.lowerType(optional_ty);
+        var buf: Type.Payload.ElemType = undefined;
+        const payload_ty = optional_ty.optionalChild(&buf);
         if (optional_ty.optionalReprIsPayload()) {
             const loaded = if (operand_is_ptr)
                 self.builder.buildLoad(optional_llvm_ty, operand, "")
             else
                 operand;
+            if (payload_ty.isSlice()) {
+                const slice_ptr = self.builder.buildExtractValue(loaded, 0, "");
+                var slice_buf: Type.SlicePtrFieldTypeBuffer = undefined;
+                const ptr_ty = try self.dg.lowerType(payload_ty.slicePtrFieldType(&slice_buf));
+                return self.builder.buildICmp(pred, slice_ptr, ptr_ty.constNull(), "");
+            }
             return self.builder.buildICmp(pred, loaded, optional_llvm_ty.constNull(), "");
         }
 
         comptime assert(optional_layout_version == 3);
 
-        var buf: Type.Payload.ElemType = undefined;
-        const payload_ty = optional_ty.optionalChild(&buf);
         if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
             const loaded = if (operand_is_ptr)
                 self.builder.buildLoad(optional_llvm_ty, operand, "")