x86_64: rewrite scalar float equality comparisons

src/arch/x86_64/Encoding.zig

@@ -361,7 +361,7 @@ pub const Mnemonic = enum {
     addps, addss,
     andps,
     andnps,
-    cmpps, cmpss,
+    cmpps, cmpss, comiss,
     cvtpi2ps, cvtps2pi, cvtsi2ss, cvtss2si, cvttps2pi, cvttss2si,
     divps, divss,
     fxrstor, fxrstor64, fxsave, fxsave64,
@@ -386,7 +386,7 @@ pub const Mnemonic = enum {
     andpd,
     andnpd,
     cmppd, //cmpsd,
-    comisd, comiss,
+    comisd,
     cvtdq2pd, cvtdq2ps, cvtpd2dq, cvtpd2pi, cvtpd2ps, cvtpi2pd,
     cvtps2dq, cvtps2pd, cvtsd2si, cvtsd2ss, cvtsi2sd, cvtss2sd,
     cvttpd2dq, cvttpd2pi, cvttps2dq, cvttsd2si,
@@ -504,6 +504,7 @@ pub const Mnemonic = enum {
     vstmxcsr,
     vsubpd, vsubps, vsubsd, vsubss,
     vtestpd, vtestps,
+    vucomisd, vucomiss,
     vxorpd, vxorps,
     // F16C
     vcvtph2ps, vcvtps2ph,

src/arch/x86_64/Mir.zig

@@ -354,6 +354,8 @@ pub const Inst = struct {
         fn_env,
         /// Float No Wait ___ status word
         fn_sw,
+        /// Float Extended ___
+        fx_,
 
         /// ___ in 32-bit and Compatibility Mode
         _32,
@@ -817,8 +819,10 @@ pub const Inst = struct {
         /// Round to integer
         rndint,
         /// Restore x87 FPU state
+        /// Restore x87 FPU, MMX, XMM, and MXCSR state
         rstor,
         /// Store x87 FPU state
+        /// Save x87 FPU, MMX technology, and MXCSR state
         save,
         /// Scale
         scale,
@@ -923,10 +927,6 @@ pub const Inst = struct {
         /// Extract doubleword
         /// Extract quadword
         extr,
-        /// Restore x87 FPU, MMX, XMM, and MXCSR state
-        fxrstor,
-        /// Save x87 FPU, MMX technology, and MXCSR state
-        fxsave,
         /// Insert byte
         /// Insert word
         /// Insert doubleword

src/arch/x86_64/bits.zig

@@ -366,7 +366,6 @@ pub const Register = enum(u8) {
             @intFromEnum(Register.eax)  ... @intFromEnum(Register.r15d)  => @intFromEnum(Register.eax),
             @intFromEnum(Register.ax)   ... @intFromEnum(Register.r15w)  => @intFromEnum(Register.ax),
             @intFromEnum(Register.al)   ... @intFromEnum(Register.r15b)  => @intFromEnum(Register.al),
-            @intFromEnum(Register.ah)   ... @intFromEnum(Register.bh)    => @intFromEnum(Register.ah) - 4,
             else => unreachable,
             // zig fmt: on
         };
@@ -385,7 +384,10 @@ pub const Register = enum(u8) {
     }
 
     pub fn to8(reg: Register) Register {
-        return @enumFromInt(@intFromEnum(reg) - reg.gpBase() + @intFromEnum(Register.al));
+        return switch (@intFromEnum(reg)) {
+            else => @enumFromInt(@intFromEnum(reg) - reg.gpBase() + @intFromEnum(Register.al)),
+            @intFromEnum(Register.ah)...@intFromEnum(Register.bh) => reg,
+        };
     }
 
     fn sseBase(reg: Register) u7 {

src/arch/x86_64/encodings.zig

@@ -437,6 +437,7 @@ pub const table = [_]Entry{
     .{ .jmp, .d, &.{ .rel32 }, &.{ 0xe9 }, 0, .none, .none },
     .{ .jmp, .m, &.{ .rm64  }, &.{ 0xff }, 4, .none, .none },
 
+    .{ .lahf, .z, &.{}, &.{ 0x9f }, 0, .none, .@"32bit" },
     .{ .lahf, .z, &.{}, &.{ 0x9f }, 0, .none, .sahf },
 
     .{ .lar, .rm, &.{ .r16, .rm16    }, &.{ 0x0f, 0x02 }, 0, .none, .none },
@@ -744,6 +745,7 @@ pub const table = [_]Entry{
 
     .{ .rsm, .z, &.{}, &.{ 0x0f, 0xaa }, 0, .none, .none },
 
+    .{ .sahf, .z, &.{}, &.{ 0x9e }, 0, .none, .@"32bit" },
     .{ .sahf, .z, &.{}, &.{ 0x9e }, 0, .none, .sahf },
 
     .{ .sal, .m1, &.{ .rm8,  .unity }, &.{ 0xd0 }, 4, .none,  .none },
@@ -2275,6 +2277,10 @@ pub const table = [_]Entry{
     .{ .vtestpd, .rm, &.{ .xmm, .xmm_m128 }, &.{ 0x66, 0x0f, 0x38, 0x0f }, 0, .vex_128_w0, .avx },
     .{ .vtestpd, .rm, &.{ .ymm, .ymm_m256 }, &.{ 0x66, 0x0f, 0x38, 0x0f }, 0, .vex_256_w0, .avx },
 
+    .{ .vucomisd, .rm, &.{ .xmm, .xmm_m64 }, &.{ 0x66, 0x0f, 0x2e }, 0, .vex_lig_wig, .avx },
+
+    .{ .vucomiss, .rm, &.{ .xmm, .xmm_m32 }, &.{ 0x0f, 0x2e }, 0, .vex_lig_wig, .avx },
+
     .{ .vxorpd, .rvm, &.{ .xmm, .xmm, .xmm_m128 }, &.{ 0x66, 0x0f, 0x57 }, 0, .vex_128_wig, .avx },
     .{ .vxorpd, .rvm, &.{ .ymm, .ymm, .ymm_m256 }, &.{ 0x66, 0x0f, 0x57 }, 0, .vex_256_wig, .avx },
 

test/behavior/x86_64/math.zig

@@ -17,8 +17,23 @@ const Sse = if (std.Target.x86.featureSetHas(builtin.cpu.features, .avx))
 else
     @Vector(16, u8);
 
-inline fn sign(rhs: anytype) bool {
+inline fn sign(rhs: anytype) switch (@typeInfo(@TypeOf(rhs))) {
-    return @call(.always_inline, math.signbit, .{rhs});
+    else => bool,
+    .vector => |vector| @Vector(vector.len, bool),
+} {
+    switch (@typeInfo(@TypeOf(rhs))) {
+        else => return @as(@Type(.{ .int = .{
+            .signedness = .signed,
+            .bits = @bitSizeOf(@TypeOf(rhs)),
+        } }), @bitCast(rhs)) < 0,
+        .vector => |vector| {
+            const V = @Vector(vector.len, @Type(.{ .int = .{
+                .signedness = .signed,
+                .bits = @bitSizeOf(vector.child),
+            } }));
+            return @as(V, @bitCast(rhs)) < @as(V, @splat(0));
+        },
+    }
 }
 inline fn boolAnd(lhs: anytype, rhs: @TypeOf(lhs)) @TypeOf(lhs) {
     switch (@typeInfo(@TypeOf(lhs))) {
@@ -69,12 +84,40 @@ noinline fn checkExpected(expected: anytype, actual: @TypeOf(expected)) !void {
     }) return error.Unexpected;
 }
 test checkExpected {
+    if (checkExpected(nan(f16), nan(f16)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(nan(f16), -nan(f16)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f16, 0.0), @as(f16, 0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f16, -0.0), @as(f16, -0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f16, -0.0), @as(f16, 0.0)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f16, 0.0), @as(f16, -0.0)) != error.Unexpected) return error.Unexpected;
+
     if (checkExpected(nan(f32), nan(f32)) == error.Unexpected) return error.Unexpected;
     if (checkExpected(nan(f32), -nan(f32)) != error.Unexpected) return error.Unexpected;
     if (checkExpected(@as(f32, 0.0), @as(f32, 0.0)) == error.Unexpected) return error.Unexpected;
     if (checkExpected(@as(f32, -0.0), @as(f32, -0.0)) == error.Unexpected) return error.Unexpected;
     if (checkExpected(@as(f32, -0.0), @as(f32, 0.0)) != error.Unexpected) return error.Unexpected;
     if (checkExpected(@as(f32, 0.0), @as(f32, -0.0)) != error.Unexpected) return error.Unexpected;
+
+    if (checkExpected(nan(f64), nan(f64)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(nan(f64), -nan(f64)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f64, 0.0), @as(f64, 0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f64, -0.0), @as(f64, -0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f64, -0.0), @as(f64, 0.0)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f64, 0.0), @as(f64, -0.0)) != error.Unexpected) return error.Unexpected;
+
+    if (checkExpected(nan(f80), nan(f80)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(nan(f80), -nan(f80)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f80, 0.0), @as(f80, 0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f80, -0.0), @as(f80, -0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f80, -0.0), @as(f80, 0.0)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f80, 0.0), @as(f80, -0.0)) != error.Unexpected) return error.Unexpected;
+
+    if (checkExpected(nan(f128), nan(f128)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(nan(f128), -nan(f128)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f128, 0.0), @as(f128, 0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f128, -0.0), @as(f128, -0.0)) == error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f128, -0.0), @as(f128, 0.0)) != error.Unexpected) return error.Unexpected;
+    if (checkExpected(@as(f128, 0.0), @as(f128, -0.0)) != error.Unexpected) return error.Unexpected;
 }
 
 fn Unary(comptime op: anytype) type {