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std.mem: check backend vector support for indexOfSentinel/indexOfScalarPos

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This commit is contained in:
Marc Tiehuis
2023-09-15 22:19:10 +12:00
parent cd766513fe
commit 5b5da0ef8c
1 changed files with 13 additions and 2 deletions
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15
lib/std/mem.zig
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@@ -953,10 +953,18 @@ test "len" {
try testing.expect(len(c_ptr) == 2);
}
const backend_supports_vectors = switch (builtin.zig_backend) {
.stage2_llvm, .stage2_c => true,
else => false,
};
pub fn indexOfSentinel(comptime T: type, comptime sentinel: T, p: [*:sentinel]const T) usize {
var i: usize = 0;
if (!@inComptime() and (@typeInfo(T) == .Int or @typeInfo(T) == .Float) and std.math.isPowerOfTwo(@bitSizeOf(T))) {
if (backend_supports_vectors and
!@inComptime() and
(@typeInfo(T) == .Int or @typeInfo(T) == .Float) and std.math.isPowerOfTwo(@bitSizeOf(T)))
{
switch (@import("builtin").cpu.arch) {
// The below branch assumes that reading past the end of the buffer is valid, as long
// as we don't read into a new page. This should be the case for most architectures
@@ -1066,7 +1074,10 @@ pub fn indexOfScalarPos(comptime T: type, slice: []const T, start_index: usize,
if (start_index >= slice.len) return null;
var i: usize = start_index;
if (!@inComptime() and (@typeInfo(T) == .Int or @typeInfo(T) == .Float) and std.math.isPowerOfTwo(@bitSizeOf(T))) {
if (backend_supports_vectors and
!@inComptime() and
(@typeInfo(T) == .Int or @typeInfo(T) == .Float) and std.math.isPowerOfTwo(@bitSizeOf(T)))
{
if (comptime std.simd.suggestVectorSize(T)) |block_len| {
// For Intel Nehalem (2009) and AMD Bulldozer (2012) or later, unaligned loads on aligned data result
// in the same execution as aligned loads. We ignore older arch's here and don't bother pre-aligning.