From b336866fbc1edd4c999d3cd5d62ae7230d176fa7 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Mon, 29 May 2023 15:30:56 -0700
Subject: InternPool: avoid indexToKey recursion for ptr_elem,ptr_field

This is a hot function, and recursion makes it more difficult to
profile, as well as likely making it more difficult to optimize.
---
 src/InternPool.zig | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

(limited to 'src/InternPool.zig')

diff --git a/src/InternPool.zig b/src/InternPool.zig
index 008f0f4df1..f1acbdfebf 100644
--- a/src/InternPool.zig
+++ b/src/InternPool.zig
@@ -2625,24 +2625,36 @@ pub fn indexToKey(ip: *const InternPool, index: Index) Key {
             } };
         },
         .ptr_elem => {
+            // Avoid `indexToKey` recursion by asserting the tag encoding.
             const info = ip.extraData(PtrBaseIndex, data);
-            return .{ .ptr = .{
-                .ty = info.ty,
-                .addr = .{ .elem = .{
-                    .base = info.base,
-                    .index = ip.indexToKey(info.index).int.storage.u64,
+            const index_item = ip.items.get(@enumToInt(info.index));
+            return switch (index_item.tag) {
+                .int_usize => .{ .ptr = .{
+                    .ty = info.ty,
+                    .addr = .{ .elem = .{
+                        .base = info.base,
+                        .index = index_item.data,
+                    } },
                 } },
-            } };
+                .int_positive => @panic("TODO"), // implement along with behavior test coverage
+                else => unreachable,
+            };
         },
         .ptr_field => {
+            // Avoid `indexToKey` recursion by asserting the tag encoding.
             const info = ip.extraData(PtrBaseIndex, data);
-            return .{ .ptr = .{
-                .ty = info.ty,
-                .addr = .{ .field = .{
-                    .base = info.base,
-                    .index = ip.indexToKey(info.index).int.storage.u64,
+            const index_item = ip.items.get(@enumToInt(info.index));
+            return switch (index_item.tag) {
+                .int_usize => .{ .ptr = .{
+                    .ty = info.ty,
+                    .addr = .{ .field = .{
+                        .base = info.base,
+                        .index = index_item.data,
+                    } },
                 } },
-            } };
+                .int_positive => @panic("TODO"), // implement along with behavior test coverage
+                else => unreachable,
+            };
         },
         .ptr_slice => {
             const info = ip.extraData(PtrSlice, data);
-- 
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