From f21c11a7f7fb84db4289a6f735dea012387606d6 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 4 May 2022 15:22:41 -0700
Subject: [PATCH] stage2: change x86_64 max int alignment from 8 to 16

For x86_64, LLVMABIAlignmentOfType(i128) reports 8. However I think 16
is a better number for two reasons:
1. Better machine code when loading into SIMD register.
2. The C ABI wants 16 for extern structs.
---
 lib/std/target.zig      | 7 ++++++-
 src/target.zig          | 9 +--------
 test/behavior/align.zig | 5 ++++-
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/lib/std/target.zig b/lib/std/target.zig
index 777b0f0ec0420840ed1c5f15a562c6b8ad7fc6e7..aab9d5acccb230e9215a234f52398d7aa3871cd6 100644
--- a/lib/std/target.zig
+++ b/lib/std/target.zig
@@ -1784,7 +1784,6 @@ pub const Target = struct {
             .armeb,
             .thumb,
             .thumbeb,
-            .x86_64,
             .hexagon,
             .mips,
             .mipsel,
@@ -1811,6 +1810,12 @@ pub const Target = struct {
                 .windows => 8,
                 else => 4,
             },
+
+            // For x86_64, LLVMABIAlignmentOfType(i128) reports 8. However I think 16
+            // is a better number because of two reasons:
+            // 1. Better machine code when loading into SIMD register.
+            // 2. The C ABI wants 16 for extern structs.
+            .x86_64,
             .aarch64,
             .aarch64_be,
             .aarch64_32,
diff --git a/src/target.zig b/src/target.zig
index 7818d496eb8fa856041dc5b104bb7a07be6c2f11..9249ed1b606fb767b036e8f70768cdad2607e7d4 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -555,7 +555,7 @@ pub const AtomicPtrAlignmentDiagnostics = struct {
     max_bits: u16 = undefined,
 };
 
-/// If ABI alignment of `ty` is OK for atomic operations, returs 0.
+/// If ABI alignment of `ty` is OK for atomic operations, returns 0.
 /// Otherwise returns the alignment required on a pointer for the target
 /// to perform atomic operations.
 pub fn atomicPtrAlignment(
@@ -645,9 +645,6 @@ pub fn atomicPtrAlignment(
                 };
                 return error.FloatTooBig;
             }
-            if (target.cpu.arch == .x86_64 and bit_count > 64) {
-                return 16;
-            }
             return 0;
         },
         .Bool => return 0,
@@ -666,10 +663,6 @@ pub fn atomicPtrAlignment(
         return error.IntTooBig;
     }
 
-    if (target.cpu.arch == .x86_64 and bit_count > 64) {
-        return 16;
-    }
-
     return 0;
 }
 
diff --git a/test/behavior/align.zig b/test/behavior/align.zig
index 9d7ca9958a8332efc9cde22b05af95f80a67ad41..393908d5bd73191cb0a1b80acc02246c3f99b7cf 100644
--- a/test/behavior/align.zig
+++ b/test/behavior/align.zig
@@ -55,6 +55,9 @@ test "alignment of struct with pointer has same alignment as usize" {
 }
 
 test "alignment and size of structs with 128-bit fields" {
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
+
     const A = struct {
         x: u128,
     };
@@ -67,7 +70,6 @@ test "alignment and size of structs with 128-bit fields" {
         .armeb,
         .thumb,
         .thumbeb,
-        .x86_64,
         .hexagon,
         .mips,
         .mipsel,
@@ -128,6 +130,7 @@ test "alignment and size of structs with 128-bit fields" {
             },
         },
 
+        .x86_64,
         .aarch64,
         .aarch64_be,
         .aarch64_32,
-- 
2.54.0