compiler-rt: compute correct integer sizes from bits at runtime

jacobly0 · jacobly0 · commit b31a91bbef2b · 2025-04-11T07:06:01.000-04:00
Also, accepting `align(1)` pointers ensures that the alignment is safety
checked rather than assumed.
diff --git a/lib/compiler_rt/divmodei4.zig b/lib/compiler_rt/divmodei4.zig
@@ -33,18 +33,20 @@ fn divmod(q: ?[]u32, r: ?[]u32, u: []u32, v: []u32) !void {
     if (r) |x| if (u_sign < 0) neg(x);
 }
 
-pub fn __divei4(r_q: [*]u32, u_p: [*]u32, v_p: [*]u32, bits: usize) callconv(.c) void {
+pub fn __divei4(q_p: [*]u8, u_p: [*]u8, v_p: [*]u8, bits: usize) callconv(.c) void {
     @setRuntimeSafety(builtin.is_test);
-    const u = u_p[0 .. std.math.divCeil(usize, bits, 32) catch unreachable];
-    const v = v_p[0 .. std.math.divCeil(usize, bits, 32) catch unreachable];
-    const q = r_q[0 .. std.math.divCeil(usize, bits, 32) catch unreachable];
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    const q: []u32 = @ptrCast(@alignCast(q_p[0..byte_size]));
+    const u: []u32 = @ptrCast(@alignCast(u_p[0..byte_size]));
+    const v: []u32 = @ptrCast(@alignCast(v_p[0..byte_size]));
     @call(.always_inline, divmod, .{ q, null, u, v }) catch unreachable;
 }
 
-pub fn __modei4(r_p: [*]u32, u_p: [*]u32, v_p: [*]u32, bits: usize) callconv(.c) void {
+pub fn __modei4(r_p: [*]u8, u_p: [*]u8, v_p: [*]u8, bits: usize) callconv(.c) void {
     @setRuntimeSafety(builtin.is_test);
-    const u = u_p[0 .. std.math.divCeil(usize, bits, 32) catch unreachable];
-    const v = v_p[0 .. std.math.divCeil(usize, bits, 32) catch unreachable];
-    const r = r_p[0 .. std.math.divCeil(usize, bits, 32) catch unreachable];
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    const r: []u32 = @ptrCast(@alignCast(r_p[0..byte_size]));
+    const u: []u32 = @ptrCast(@alignCast(u_p[0..byte_size]));
+    const v: []u32 = @ptrCast(@alignCast(v_p[0..byte_size]));
     @call(.always_inline, divmod, .{ null, r, u, v }) catch unreachable;
 }
diff --git a/lib/compiler_rt/fixdfei.zig b/lib/compiler_rt/fixdfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixdfei, .{ .name = "__fixdfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixdfei(r: [*]u32, bits: usize, a: f64) callconv(.c) void {
-    return bigIntFromFloat(.signed, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixdfei(r: [*]u8, bits: usize, a: f64) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.signed, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixhfei.zig b/lib/compiler_rt/fixhfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixhfei, .{ .name = "__fixhfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixhfei(r: [*]u32, bits: usize, a: f16) callconv(.c) void {
-    return bigIntFromFloat(.signed, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixhfei(r: [*]u8, bits: usize, a: f16) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.signed, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixsfei.zig b/lib/compiler_rt/fixsfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixsfei, .{ .name = "__fixsfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixsfei(r: [*]u32, bits: usize, a: f32) callconv(.c) void {
-    return bigIntFromFloat(.signed, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixsfei(r: [*]u8, bits: usize, a: f32) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.signed, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixtfei.zig b/lib/compiler_rt/fixtfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixtfei, .{ .name = "__fixtfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixtfei(r: [*]u32, bits: usize, a: f128) callconv(.c) void {
-    return bigIntFromFloat(.signed, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixtfei(r: [*]u8, bits: usize, a: f128) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.signed, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixunsdfei.zig b/lib/compiler_rt/fixunsdfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixunsdfei, .{ .name = "__fixunsdfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixunsdfei(r: [*]u32, bits: usize, a: f64) callconv(.c) void {
-    return bigIntFromFloat(.unsigned, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixunsdfei(r: [*]u8, bits: usize, a: f64) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.unsigned, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixunshfei.zig b/lib/compiler_rt/fixunshfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixunshfei, .{ .name = "__fixunshfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixunshfei(r: [*]u32, bits: usize, a: f16) callconv(.c) void {
-    return bigIntFromFloat(.unsigned, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixunshfei(r: [*]u8, bits: usize, a: f16) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.unsigned, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixunssfei.zig b/lib/compiler_rt/fixunssfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixunssfei, .{ .name = "__fixunssfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixunssfei(r: [*]u32, bits: usize, a: f32) callconv(.c) void {
-    return bigIntFromFloat(.unsigned, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixunssfei(r: [*]u8, bits: usize, a: f32) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.unsigned, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixunstfei.zig b/lib/compiler_rt/fixunstfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixunstfei, .{ .name = "__fixunstfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixunstfei(r: [*]u32, bits: usize, a: f128) callconv(.c) void {
-    return bigIntFromFloat(.unsigned, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixunstfei(r: [*]u8, bits: usize, a: f128) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.unsigned, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixunsxfei.zig b/lib/compiler_rt/fixunsxfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixunsxfei, .{ .name = "__fixunsxfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixunsxfei(r: [*]u32, bits: usize, a: f80) callconv(.c) void {
-    return bigIntFromFloat(.unsigned, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixunsxfei(r: [*]u8, bits: usize, a: f80) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.unsigned, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/fixxfei.zig b/lib/compiler_rt/fixxfei.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const bigIntFromFloat = @import("./int_from_float.zig").bigIntFromFloat;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const bigIntFromFloat = @import("int_from_float.zig").bigIntFromFloat;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__fixxfei, .{ .name = "__fixxfei", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __fixxfei(r: [*]u32, bits: usize, a: f80) callconv(.c) void {
-    return bigIntFromFloat(.signed, r[0 .. divCeil(usize, bits, 32) catch unreachable], a);
+pub fn __fixxfei(r: [*]u8, bits: usize, a: f80) callconv(.c) void {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return bigIntFromFloat(.signed, @ptrCast(@alignCast(r[0..byte_size])), a);
 }
diff --git a/lib/compiler_rt/float_from_int_test.zig b/lib/compiler_rt/float_from_int_test.zig
@@ -1,8 +1,6 @@
 const std = @import("std");
-const builtin = @import("builtin");
 const testing = std.testing;
 const math = std.math;
-const endian = builtin.cpu.arch.endian();
 
 const __floatunsihf = @import("floatunsihf.zig").__floatunsihf;
 
@@ -237,12 +235,10 @@ test "floatuntisf" {
 
 fn test_floateisf(expected: u32, comptime T: type, a: T) !void {
     const int = @typeInfo(T).int;
-    var a_buf: [@divExact(int.bits, 32)]u32 = undefined;
-    std.mem.writeInt(T, std.mem.asBytes(&a_buf), a, endian);
     const r = switch (int.signedness) {
         .signed => __floateisf,
         .unsigned => __floatuneisf,
-    }(&a_buf, int.bits);
+    }(@ptrCast(&a), int.bits);
     try testing.expect(expected == @as(u32, @bitCast(r)));
 }
 
diff --git a/lib/compiler_rt/floateidf.zig b/lib/compiler_rt/floateidf.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const floatFromBigInt = @import("./float_from_int.zig").floatFromBigInt;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const floatFromBigInt = @import("float_from_int.zig").floatFromBigInt;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__floateidf, .{ .name = "__floateidf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floateidf(a: [*]const u32, bits: usize) callconv(.c) f64 {
-    return floatFromBigInt(f64, .signed, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floateidf(a: [*]const u8, bits: usize) callconv(.c) f64 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f64, .signed, @ptrCast(@alignCast(a[0..byte_size])));
 }
diff --git a/lib/compiler_rt/floateihf.zig b/lib/compiler_rt/floateihf.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const floatFromBigInt = @import("./float_from_int.zig").floatFromBigInt;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const floatFromBigInt = @import("float_from_int.zig").floatFromBigInt;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__floateihf, .{ .name = "__floateihf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floateihf(a: [*]const u32, bits: usize) callconv(.c) f16 {
-    return floatFromBigInt(f16, .signed, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floateihf(a: [*]const u8, bits: usize) callconv(.c) f16 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f16, .signed, @ptrCast(@alignCast(a[0..byte_size])));
 }
diff --git a/lib/compiler_rt/floateisf.zig b/lib/compiler_rt/floateisf.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const floatFromBigInt = @import("./float_from_int.zig").floatFromBigInt;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const floatFromBigInt = @import("float_from_int.zig").floatFromBigInt;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__floateisf, .{ .name = "__floateisf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floateisf(a: [*]const u32, bits: usize) callconv(.c) f32 {
-    return floatFromBigInt(f32, .signed, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floateisf(a: [*]const u8, bits: usize) callconv(.c) f32 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f32, .signed, @ptrCast(@alignCast(a[0..byte_size])));
 }
diff --git a/lib/compiler_rt/floateitf.zig b/lib/compiler_rt/floateitf.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const floatFromBigInt = @import("./float_from_int.zig").floatFromBigInt;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const floatFromBigInt = @import("float_from_int.zig").floatFromBigInt;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__floateitf, .{ .name = "__floateitf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floateitf(a: [*]const u32, bits: usize) callconv(.c) f128 {
-    return floatFromBigInt(f128, .signed, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floateitf(a: [*]const u8, bits: usize) callconv(.c) f128 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f128, .signed, @ptrCast(@alignCast(a[0..byte_size])));
 }
diff --git a/lib/compiler_rt/floateixf.zig b/lib/compiler_rt/floateixf.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const floatFromBigInt = @import("./float_from_int.zig").floatFromBigInt;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const floatFromBigInt = @import("float_from_int.zig").floatFromBigInt;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__floateixf, .{ .name = "__floateixf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floateixf(a: [*]const u32, bits: usize) callconv(.c) f80 {
-    return floatFromBigInt(f80, .signed, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floateixf(a: [*]const u8, bits: usize) callconv(.c) f80 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f80, .signed, @ptrCast(@alignCast(a[0..byte_size])));
 }
diff --git a/lib/compiler_rt/floatuneidf.zig b/lib/compiler_rt/floatuneidf.zig
@@ -1,13 +1,15 @@
-const divCeil = @import("std").math.divCeil;
-const common = @import("./common.zig");
-const floatFromBigInt = @import("./float_from_int.zig").floatFromBigInt;
+const std = @import("std");
+const builtin = @import("builtin");
+const common = @import("common.zig");
+const floatFromBigInt = @import("float_from_int.zig").floatFromBigInt;
 
 pub const panic = common.panic;
 
 comptime {
     @export(&__floatuneidf, .{ .name = "__floatuneidf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floatuneidf(a: [*]const u32, bits: usize) callconv(.c) f64 {
-    return floatFromBigInt(f64, .unsigned, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floatuneidf(a: [*]const u8, bits: usize) callconv(.c) f64 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f64, .unsigned, @ptrCast(@alignCast(a[0..byte_size])));
 }
diff --git a/lib/compiler_rt/floatuneihf.zig b/lib/compiler_rt/floatuneihf.zig
diff --git a/lib/compiler_rt/floatuneisf.zig b/lib/compiler_rt/floatuneisf.zig
diff --git a/lib/compiler_rt/floatuneitf.zig b/lib/compiler_rt/floatuneitf.zig
diff --git a/lib/compiler_rt/floatuneixf.zig b/lib/compiler_rt/floatuneixf.zig
diff --git a/lib/compiler_rt/int_from_float_test.zig b/lib/compiler_rt/int_from_float_test.zig
diff --git a/lib/compiler_rt/udivmodei4.zig b/lib/compiler_rt/udivmodei4.zig
