Refactor some `char`, `u8` ascii functions to be branchless

Decompose singular `matches!` with or-patterns to individual `matches!`
statements to enable branchless code output. The following functions
were changed:
- `is_ascii_alphanumeric`
- `is_ascii_hexdigit`
- `is_ascii_punctuation`

Add codegen tests

Co-authored-by: George Bateman <george.bateman16@gmail.com>
Co-authored-by: scottmcm <scottmcm@users.noreply.github.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/tests/codegen/char-ascii-branchless.rs b/tests/codegen/char-ascii-branchless.rs
new file mode 100644
index 00000000000..b612b24c7c7
--- /dev/null
+++ b/tests/codegen/char-ascii-branchless.rs
@@ -0,0 +1,47 @@
+// Checks that these functions are branchless.
+//
+// compile-flags: -O
+
+#![crate_type = "lib"]
+
+// CHECK-LABEL: @is_ascii_alphanumeric_char
+#[no_mangle]
+pub fn is_ascii_alphanumeric_char(x: char) -> bool {
+    // CHECK-NOT: br
+    x.is_ascii_alphanumeric()
+}
+
+// CHECK-LABEL: @is_ascii_alphanumeric_u8
+#[no_mangle]
+pub fn is_ascii_alphanumeric_u8(x: u8) -> bool {
+    // CHECK-NOT: br
+    x.is_ascii_alphanumeric()
+}
+
+// CHECK-LABEL: @is_ascii_hexdigit_char
+#[no_mangle]
+pub fn is_ascii_hexdigit_char(x: char) -> bool {
+    // CHECK-NOT: br
+    x.is_ascii_hexdigit()
+}
+
+// CHECK-LABEL: @is_ascii_hexdigit_u8
+#[no_mangle]
+pub fn is_ascii_hexdigit_u8(x: u8) -> bool {
+    // CHECK-NOT: br
+    x.is_ascii_hexdigit()
+}
+
+// CHECK-LABEL: @is_ascii_punctuation_char
+#[no_mangle]
+pub fn is_ascii_punctuation_char(x: char) -> bool {
+    // CHECK-NOT: br
+    x.is_ascii_punctuation()
+}
+
+// CHECK-LABEL: @is_ascii_punctuation_u8
+#[no_mangle]
+pub fn is_ascii_punctuation_u8(x: u8) -> bool {
+    // CHECK-NOT: br
+    x.is_ascii_punctuation()
+}