From dae7c7c466500733ef74c72874e7755cc3f218b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Sun, 11 Oct 2026 09:18:36 +0200
Subject: [PATCH] compiler_rt.elf.tls: add ___tls_get_addr() which is used by
 32-bit x86

As per usual, we have GNU to thank.
---
 lib/compiler_rt/elf/tls.zig | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/lib/compiler_rt/elf/tls.zig b/lib/compiler_rt/elf/tls.zig
index dccd2018ce02a2b32050b239a30f9d30dc9d06bd..1d53b6de023feb126a9a459a642ed7798ff414c8 100644
--- a/lib/compiler_rt/elf/tls.zig
+++ b/lib/compiler_rt/elf/tls.zig
@@ -29,10 +29,14 @@ comptime {
     // function for the GD and LD models. This function is unlikely to actually be used, since the
     // linker should be able to relax every TLS access to the LE model and therefore eliminate all
     // calls to this function, but that isn't guaranteed.
-    if (native_arch == .s390x)
-        symbol(&__tls_get_offset, "__tls_get_offset")
-    else
+    if (native_arch == .s390x) {
+        symbol(&__tls_get_offset, "__tls_get_offset");
+    } else {
         symbol(&__tls_get_addr, "__tls_get_addr");
+        if (native_arch == .x86) {
+            symbol(&___tls_get_addr, "___tls_get_addr");
+        }
+    }
 }
 
 /// Represents an ELF TLS variant.
@@ -740,6 +744,18 @@ fn __tls_get_addr(ti: *const TlsIndex) callconv(.c) *anyopaque {
     return block[@intCast(ti.offset)..];
 }
 
+fn ___tls_get_addr() callconv(.naked) *anyopaque {
+    comptime assert(native_arch == .x86);
+
+    // We receive the `TlsIndex` pointer in eax.
+    comptime assert(@sizeOf(AbiTcb) + @sizeOf(ZigTcb) + @offsetOf(Dtv, "tls_block") == 12);
+    asm volatile (
+        \\ mov 4(%%eax), %%eax
+        \\ add %%gs:12, %%eax
+        \\ ret
+    );
+}
+
 fn __tls_get_offset() callconv(.naked) noreturn {
     comptime assert(native_arch == .s390x);
 
-- 
2.54.0