From fc7a0c4878dac2d721ec18cafe1b6bcff7faa771 Mon Sep 17 00:00:00 2001
From: Alex Rønne Petersen <alex@alexrp.com>
Date: Sat, 15 Feb 2025 02:44:58 +0100
Subject: Sema: Fix fnptr alignment safety checks to account for potential ISA
 tag.

As seen on e.g. Arm/Thumb and MIPS (MIPS16/microMIPS).

Fixes #22888.
---
 src/target.zig | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'src/target.zig')

diff --git a/src/target.zig b/src/target.zig
index 8ccec7f7a8..d032b0d16e 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -626,6 +626,17 @@ pub fn supportsFunctionAlignment(target: std.Target) bool {
     };
 }
 
+pub fn functionPointerMask(target: std.Target) ?u64 {
+    // 32-bit Arm uses the LSB to mean that the target function contains Thumb code.
+    // MIPS uses the LSB to mean that the target function contains MIPS16/microMIPS code.
+    return if (target.cpu.arch.isArm() or target.cpu.arch.isMIPS32())
+        ~@as(u32, 1)
+    else if (target.cpu.arch.isMIPS64())
+        ~@as(u64, 1)
+    else
+        null;
+}
+
 pub fn supportsTailCall(target: std.Target, backend: std.builtin.CompilerBackend) bool {
     switch (backend) {
         .stage1, .stage2_llvm => return @import("codegen/llvm.zig").supportsTailCall(target),
-- 
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