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

Also, accepting `align(1)` pointers ensures that the alignment is safety
checked rather than assumed.

1 files changed, 7 insertions, 5 deletions

diff --git a/lib/compiler_rt/floatuneitf.zig b/lib/compiler_rt/floatuneitf.zig
index 61c2c93b28..727d301f7b 100644
--- a/lib/compiler_rt/floatuneitf.zig
+++ b/lib/compiler_rt/floatuneitf.zig
@@ -1,6 +1,7 @@
-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;
 
@@ -8,6 +9,7 @@ comptime {
     @export(&__floatuneitf, .{ .name = "__floatuneitf", .linkage = common.linkage, .visibility = common.visibility });
 }
 
-pub fn __floatuneitf(a: [*]const u32, bits: usize) callconv(.c) f128 {
-    return floatFromBigInt(f128, .unsigned, a[0 .. divCeil(usize, bits, 32) catch unreachable]);
+pub fn __floatuneitf(a: [*]const u8, bits: usize) callconv(.c) f128 {
+    const byte_size = std.zig.target.intByteSize(builtin.target, @intCast(bits));
+    return floatFromBigInt(f128, .unsigned, @ptrCast(@alignCast(a[0..byte_size])));
 }