From afe2fed34dd960afb44f88cfe6ce088e1817cb5b Mon Sep 17 00:00:00 2001
From: Alex Rønne Petersen <alex@alexrp.com>
Date: Mon, 16 Dec 2024 06:07:02 +0100
Subject: link: Set machine and float ABI when invoking ld.lld and lld-link.

If this isn't done, LTO can completely miscompile the input bitcode modules for
certain targets where we need to explicitly set these ABIs (because LLVM's
defaults are bad).
---
 src/link/Coff.zig |  7 +++++++
 src/link/Elf.zig  | 12 ++++++++++++
 2 files changed, 19 insertions(+)

(limited to 'src')

diff --git a/src/link/Coff.zig b/src/link/Coff.zig
index 9bd3bd76e9..3b239246ca 100644
--- a/src/link/Coff.zig
+++ b/src/link/Coff.zig
@@ -1876,6 +1876,13 @@ fn linkWithLLD(coff: *Coff, arena: Allocator, tid: Zcu.PerThread.Id, prog_node:
         if (comp.version) |version| {
             try argv.append(try allocPrint(arena, "-VERSION:{}.{}", .{ version.major, version.minor }));
         }
+
+        if (target_util.llvmMachineAbi(target)) |mabi| {
+            try argv.append(try allocPrint(arena, "-MLLVM:-target-abi={s}", .{mabi}));
+        }
+
+        try argv.append(try allocPrint(arena, "-MLLVM:-float-abi={s}", .{if (target.abi.floatAbi() == .hard) "hard" else "soft"}));
+
         if (comp.config.lto != .none) {
             switch (optimize_mode) {
                 .Debug => {},
diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index ea2fa56a5d..edd45f65ee 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -1700,6 +1700,18 @@ fn linkWithLLD(self: *Elf, arena: Allocator, tid: Zcu.PerThread.Id, prog_node: s
             try argv.append(try std.fmt.allocPrint(arena, "--sysroot={s}", .{sysroot}));
         }
 
+        if (target_util.llvmMachineAbi(target)) |mabi| {
+            try argv.appendSlice(&.{
+                "-mllvm",
+                try std.fmt.allocPrint(arena, "-target-abi={s}", .{mabi}),
+            });
+        }
+
+        try argv.appendSlice(&.{
+            "-mllvm",
+            try std.fmt.allocPrint(arena, "-float-abi={s}", .{if (target.abi.floatAbi() == .hard) "hard" else "soft"}),
+        });
+
         if (comp.config.lto != .none) {
             switch (comp.root_mod.optimize_mode) {
                 .Debug => {},
-- 
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