From 1b657e6e41bcaf362d1cc9455c17e06e57973554 Mon Sep 17 00:00:00 2001
From: joachimschmidt557 <joachim.schmidt557@outlook.com>
Date: Sat, 27 Mar 2021 22:23:14 +0100
Subject: stage2 codegen: Make sure function return value is in a callee
 preserved register

---
 src/codegen.zig | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'src/codegen.zig')

diff --git a/src/codegen.zig b/src/codegen.zig
index 6365d66ec6..bc3480ca01 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -2194,6 +2194,16 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
                 unreachable;
             }
 
+            switch (info.return_value) {
+                .register => |reg| {
+                    if (Register.allocIndex(reg) == null) {
+                        // Save function return value in a callee saved register
+                        return try self.copyToNewRegister(&inst.base, info.return_value);
+                    }
+                },
+                else => {},
+            }
+
             return info.return_value;
         }
 
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