language-servers/roc
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improvements to str.zig

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This commit is contained in:
Folkert 2020-12-12 01:46:33 +01:00
parent 3ec8832e62
commit 20c041dc60
1 changed files with 13 additions and 16 deletions
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29
compiler/builtins/bitcode/src/str.zig
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@ -12,7 +12,7 @@ const InPlace = packed enum(u8) {
Clone, Clone,
}; };
const RocStr = extern struct { pub const RocStr = extern struct {
str_bytes: ?[*]u8, str_bytes: ?[*]u8,
str_len: usize, str_len: usize,
@ -181,10 +181,16 @@ const RocStr = extern struct {
return self.len() == 0; return self.len() == 0;
} }
pub fn asSlice(self: RocStr) []u8 {
// Since this conditional would be prone to branch misprediction,
// make sure it will compile to a cmov.
return self.asU8ptr()[0..self.len()];
}
pub fn asU8ptr(self: RocStr) [*]u8 { pub fn asU8ptr(self: RocStr) [*]u8 {
const if_small = &@bitCast([16]u8, self); // Since this conditional would be prone to branch misprediction,
const if_big = @ptrCast([*]u8, self.str_bytes); // make sure it will compile to a cmov.
return if (self.isSmallStr() or self.isEmpty()) if_small else if_big; return if (self.isSmallStr() or self.isEmpty()) (&@bitCast([16]u8, self)) else (@ptrCast([*]u8, self.str_bytes));
} }
// Given a pointer to some bytes, write the first (len) bytes of this // Given a pointer to some bytes, write the first (len) bytes of this
@ -193,18 +199,9 @@ const RocStr = extern struct {
// One use for this function is writing into an `alloca` for a C string that // One use for this function is writing into an `alloca` for a C string that
// only needs to live long enough to be passed as an argument to // only needs to live long enough to be passed as an argument to
// a C function - like the file path argument to `fopen`. // a C function - like the file path argument to `fopen`.
pub fn memcpy(self: RocStr, dest: [*]u8, len: usize) void { pub fn memcpy(self: RocStr, dest: [*]u8, length: usize) void {
const small_src = @ptrCast(*u8, self); const src = self.asU8ptr();
const big_src = self.str_bytes_ptr; @memcpy(dest, src, length);
// For a small string, copy the bytes directly from `self`.
// For a large string, copy from the pointed-to bytes.
// Since this conditional would be prone to branch misprediction,
// make sure it will compile to a cmov.
const src: [*]u8 = if (self.isSmallStr()) small_src else big_src;
@memcpy(dest, src, len);
} }
test "RocStr.eq: equal" { test "RocStr.eq: equal" {