From 07a7c2f7c86d72bd15e980d098aa2b46f236412f Mon Sep 17 00:00:00 2001
From: Veikka Tuominen <git@vexu.eu>
Date: Mon, 26 Sep 2022 13:54:52 +0300
Subject: [PATCH] stage2: remove redundant `is_ref` flag from
 `SwitchBlock.Bits`

---
 src/AstGen.zig    | 1 -
 src/Sema.zig      | 9 +++------
 src/Zir.zig       | 5 +----
 src/print_zir.zig | 1 -
 4 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/src/AstGen.zig b/src/AstGen.zig
index a516043bf2..fcf5835f1e 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -6520,7 +6520,6 @@ fn switchExpr(
     const payload_index = astgen.addExtraAssumeCapacity(Zir.Inst.SwitchBlock{
         .operand = cond,
         .bits = Zir.Inst.SwitchBlock.Bits{
-            .is_ref = any_payload_is_ref,
             .has_multi_cases = multi_cases_len != 0,
             .has_else = special_prong == .@"else",
             .has_under = special_prong == .under,
diff --git a/src/Sema.zig b/src/Sema.zig
index 72a5cb518f..f6a84341cc 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -8994,9 +8994,10 @@ fn zirSwitchCapture(
     const switch_info = zir_datas[capture_info.switch_inst].pl_node;
     const switch_extra = sema.code.extraData(Zir.Inst.SwitchBlock, switch_info.payload_index);
     const operand_src: LazySrcLoc = .{ .node_offset_switch_operand = switch_info.src_node };
-    const operand_is_ref = switch_extra.data.bits.is_ref;
     const cond_inst = Zir.refToIndex(switch_extra.data.operand).?;
-    const cond_info = sema.code.instructions.items(.data)[cond_inst].un_node;
+    const cond_info = zir_datas[cond_inst].un_node;
+    const cond_tag = sema.code.instructions.items(.tag)[cond_inst];
+    const operand_is_ref = cond_tag == .switch_cond_ref;
     const operand_ptr = try sema.resolveInst(cond_info.operand);
     const operand_ptr_ty = sema.typeOf(operand_ptr);
     const operand_ty = if (operand_is_ref) operand_ptr_ty.childType() else operand_ptr_ty;
@@ -9009,7 +9010,6 @@ fn zirSwitchCapture(
     if (capture_info.prong_index == std.math.maxInt(@TypeOf(capture_info.prong_index))) {
         // It is the else/`_` prong.
         if (is_ref) {
-            assert(operand_is_ref);
             return operand_ptr;
         }
 
@@ -9069,8 +9069,6 @@ fn zirSwitchCapture(
             }
 
             if (is_ref) {
-                assert(operand_is_ref);
-
                 const field_ty_ptr = try Type.ptr(sema.arena, sema.mod, .{
                     .pointee_type = first_field.ty,
                     .@"addrspace" = .generic,
@@ -9131,7 +9129,6 @@ fn zirSwitchCapture(
             // In this case the capture value is just the passed-through value of the
             // switch condition.
             if (is_ref) {
-                assert(operand_is_ref);
                 return operand_ptr;
             } else {
                 return operand;
diff --git a/src/Zir.zig b/src/Zir.zig
index 5b1aefea64..24248a6533 100644
--- a/src/Zir.zig
+++ b/src/Zir.zig
@@ -2952,12 +2952,9 @@ pub const Inst = struct {
             has_else: bool,
             /// If true, there is an underscore prong. This is mutually exclusive with `has_else`.
             has_under: bool,
-            /// If true, the `operand` is a pointer to the value being switched on.
-            /// TODO this flag is redundant with the tag of operand and can be removed.
-            is_ref: bool,
             scalar_cases_len: ScalarCasesLen,
 
-            pub const ScalarCasesLen = u28;
+            pub const ScalarCasesLen = u29;
 
             pub fn specialProng(bits: Bits) SpecialProng {
                 const has_else: u2 = @boolToInt(bits.has_else);
diff --git a/src/print_zir.zig b/src/print_zir.zig
index b273365596..1d7083e8f1 100644
--- a/src/print_zir.zig
+++ b/src/print_zir.zig
@@ -1857,7 +1857,6 @@ const Writer = struct {
         } else 0;
 
         try self.writeInstRef(stream, extra.data.operand);
-        try self.writeFlag(stream, ", ref", extra.data.bits.is_ref);
 
         self.indent += 2;