fix(lexer): size the SIMD identifier scan by lane count, not byte size

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src/lexer.zigmodified+10-3

Changes to src/lexer.zig

		⋯319 linesShow the 319 lines above this hunk@@ -320,6 +320,13 @@ pub const Lexer = struct {
320	320	/// original boundary. The scalar tail also covers short identifiers.
321	321	inline fn consumeAsciiIdentPart(self: *Lexer) void {
322	322	const Block = @Vector(8, u8);
	323	+ // Lane count, taken from the type so the two cannot drift. Deliberately
	324	+ // not the vector's byte size: a vector is padded up to its alignment,
	325	+ // so that is 16 on x86_64 and 8 on aarch64. Sizing the loop by it
	326	+ // happened to match the lane count on one target and not the other,
	327	+ // where it does not even compile — slicing 16 bytes to coerce into an
	328	+ // 8-lane vector is `expected type '@Vector(8, u8)', found '[16]u8'`.
	329	+ const lanes = @typeInfo(Block).vector.len;
323	330	const lower_a: Block = @splat('a');
324	331	const lower_z: Block = @splat('z');
325	332	const upper_a: Block = @splat('A');
		⋯2 linesShow the 2 lines above this hunk@@ -328,14 +335,14 @@ pub const Lexer = struct {
328	335	const digit_9: Block = @splat('9');
329	336	const underscore: Block = @splat('_');
330	337	const dollar: Block = @splat('$');
331		- while (self.src.len - self.i >= @sizeOf(Block)) {
332		- const bytes: Block = self.src[self.i..][0..@sizeOf(Block)].*;
	338	+ while (self.src.len - self.i >= lanes) {
	339	+ const bytes: Block = self.src[self.i..][0..lanes].*;
333	340	const valid = ((bytes >= lower_a) & (bytes <= lower_z)) |
334	341	((bytes >= upper_a) & (bytes <= upper_z)) |
335	342	((bytes >= digit_0) & (bytes <= digit_9)) |
336	343	(bytes == underscore) | (bytes == dollar);
337	344	if (!@reduce(.And, valid)) break;
338		- self.i += @sizeOf(Block);
	345	+ self.i += lanes;
339	346	}
340	347	while (self.i < self.src.len and isIdentPart(self.src[self.i])) self.i += 1;
341	348	}