From 924679abc46deeaae9284ab6ce928aaddb0fae95 Mon Sep 17 00:00:00 2001
From: Dan Ellis Echavarria <19101das@gmail.com>
Date: Wed, 7 Sep 2022 07:22:30 -0500
Subject: [PATCH] std.simd: change T to u16

The `element_bit_size` would break if `T` was signed due to `ceilPowerOfTwo` only working on unsigned numbers.
---
 lib/std/simd.zig | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/std/simd.zig b/lib/std/simd.zig
index b2655758c0..972bf136e9 100644
--- a/lib/std/simd.zig
+++ b/lib/std/simd.zig
@@ -9,7 +9,7 @@ const builtin = @import("builtin");
 pub fn suggestVectorSizeForCpu(comptime T: type, comptime cpu: std.Target.Cpu) ?usize {
     // This is guesswork, if you have better suggestions can add it or edit the current here
     // This can run in comptime only, but stage 1 fails at it, stage 2 can understand it
-    const element_bit_size = @maximum(8, std.math.ceilPowerOfTwo(T, @bitSizeOf(T)) catch unreachable);
+    const element_bit_size = @maximum(8, std.math.ceilPowerOfTwo(u16, @bitSizeOf(T)) catch unreachable);
     const vector_bit_size: u16 = blk: {
         if (cpu.arch.isX86()) {
             if (T == bool and std.Target.x86.featureSetHas(.prefer_mask_registers)) return 64;
@@ -57,6 +57,15 @@ pub fn suggestVectorSize(comptime T: type) ?usize {
     return suggestVectorSizeForCpu(T, builtin.cpu);
 }
 
+test "suggestVectorSizeForCpu works with signed and unsigned values" {
+    comptime var cpu = std.Target.Cpu.baseline(std.Target.Cpu.Arch.x86_64);
+    comptime cpu.features.addFeature(@enumToInt(std.Target.x86.Feature.avx512f));
+    const signed_integer_size = suggestVectorSizeForCpu(i32, cpu).?;
+    const unsigned_integer_size = suggestVectorSizeForCpu(u32, cpu).?;
+    try std.testing.expectEqual(@as(usize, 16), unsigned_integer_size);
+    try std.testing.expectEqual(@as(usize, 16), signed_integer_size);
+}
+
 fn vectorLength(comptime VectorType: type) comptime_int {
     return switch (@typeInfo(VectorType)) {
         .Vector => |info| info.len,