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stage2: emit Value.repeated for ** where the array size is one

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This takes advantage of the repeated value.
This commit is contained in:
Jacob G-W 2021-09-30 21:31:46 -04:00
parent b0e89ee499
commit 83dcd9f038
2 changed files with 20 additions and 9 deletions
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24
src/Sema.zig
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@ -6189,16 +6189,22 @@ fn zirArrayMul(sema: *Sema, block: *Scope.Block, inst: Zir.Inst.Index) CompileEr
try Type.Tag.array.create(anon_decl.arena(), .{ .len = final_len, .elem_type = mulinfo.elem_type });
const buf = try anon_decl.arena().alloc(Value, final_len);
// the actual loop
var i: u64 = 0;
while (i < tomulby) : (i += 1) {
var j: u64 = 0;
while (j < mulinfo.len) : (j += 1) {
const val = try lhs_sub_val.elemValue(sema.arena, j);
buf[mulinfo.len * i + j] = try val.copy(anon_decl.arena());
// handles the optimisation where arr.len == 0 : [_]T { X } ** N
const val = if (mulinfo.len == 1) blk: {
const copied_val = try (try lhs_sub_val.elemValue(sema.arena, 0)).copy(anon_decl.arena());
break :blk try Value.Tag.repeated.create(anon_decl.arena(), copied_val);
} else blk: {
// the actual loop
var i: u64 = 0;
while (i < tomulby) : (i += 1) {
var j: u64 = 0;
while (j < mulinfo.len) : (j += 1) {
const val = try lhs_sub_val.elemValue(sema.arena, j);
buf[mulinfo.len * i + j] = try val.copy(anon_decl.arena());
}
}
}
const val = try Value.Tag.array.create(anon_decl.arena(), buf);
break :blk try Value.Tag.array.create(anon_decl.arena(), buf);
};
if (lhs_ty.zigTypeTag() == .Pointer) {
return sema.analyzeDeclRef(try anon_decl.finish(final_ty, val));
} else {

5
test/behavior/array.zig
View File

@ -32,4 +32,9 @@ test "array init with mult" {
const a = 'a';
var i: [8]u8 = [2]u8{ a, 'b' } ** 4;
try expect(std.mem.eql(u8, &i, "abababab"));
// this should cause a Value.repeated to be emitted in AIR.
// TODO: find a way to test that this is actually getting emmited
var j: [4]u8 = [1]u8{'a'} ** 4;
try expect(std.mem.eql(u8, &j, "aaaa"));
}