From 3bf9a8feb50c3ff20da80593a735ec3244cb5d89 Mon Sep 17 00:00:00 2001
From: Jacob Young <jacobly0@users.noreply.github.com>
Date: Sun, 8 Oct 2023 02:13:33 -0400
Subject: [PATCH] x86_64: fix `@divTrunc` and `@divFloor` of `f16`

---
 src/arch/x86_64/CodeGen.zig | 17 +++++++++++++++++
 test/behavior/math.zig      |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig
index bdad8312d5..46682345b9 100644
--- a/src/arch/x86_64/CodeGen.zig
+++ b/src/arch/x86_64/CodeGen.zig
@@ -7177,6 +7177,23 @@ fn genBinOp(
                     dst_reg,
                     tmp_reg,
                 );
+                switch (air_tag) {
+                    .div_trunc, .div_floor => try self.asmRegisterRegisterRegisterImmediate(
+                        .{ .v_ss, .round },
+                        dst_reg,
+                        dst_reg,
+                        dst_reg,
+                        Immediate.u(@as(u5, @bitCast(RoundMode{
+                            .mode = switch (air_tag) {
+                                .div_trunc => .zero,
+                                .div_floor => .down,
+                                else => unreachable,
+                            },
+                            .precision = .inexact,
+                        }))),
+                    ),
+                    else => {},
+                }
                 try self.asmRegisterRegisterImmediate(
                     .{ .v_, .cvtps2ph },
                     dst_reg,
diff --git a/test/behavior/math.zig b/test/behavior/math.zig
index c29ef4ad8c..e017a62aa6 100644
--- a/test/behavior/math.zig
+++ b/test/behavior/math.zig
@@ -495,11 +495,11 @@ fn testDivision() !void {
 }
 
 test "division half-precision floats" {
-    if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_x86_64 and builtin.target.ofmt != .elf) return error.SkipZigTest;
 
     try testDivisionFP16();
     try comptime testDivisionFP16();