aboutsummaryrefslogtreecommitdiff
path: root/src/long_mode/mod.rs
diff options
context:
space:
mode:
authoriximeow <me@iximeow.net>2021-07-01 21:03:04 -0700
committeriximeow <me@iximeow.net>2021-07-01 23:54:28 -0700
commit0637f629067c0aa8777466fa8e6e3ac4280356b1 (patch)
treeac1c78c0a13dd82e6dfea2ab1caa1c63a59ff698 /src/long_mode/mod.rs
parenta781322552d9fb52b7b5e51641f49f12678f682f (diff)
reorder prefix checks
this measures a bit faster. it doesn't seem like it should be. the rex prefix checks compile identically but move a lea for a later expression up and pipelines better?
Diffstat (limited to 'src/long_mode/mod.rs')
-rw-r--r--src/long_mode/mod.rs25
1 files changed, 13 insertions, 12 deletions
diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs
index d04a091..65b1a35 100644
--- a/src/long_mode/mod.rs
+++ b/src/long_mode/mod.rs
@@ -6980,22 +6980,23 @@ fn read_instr<T: Reader<<Arch as yaxpeax_arch::Arch>::Address, <Arch as yaxpeax_
return Err(DecodeError::TooLong);
}
let record = OPCODES[b as usize];
- if (b & 0xf0) == 0x40 {
+ if b >= 0x40 && b < 0x50 {
prefixes.rex_from(b);
- } else if b == 0x0f {
- let b = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
- if b == 0x38 {
- let b = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
- break read_0f38_opcode(b, &mut prefixes);
- } else if b == 0x3a {
- let b = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
- break read_0f3a_opcode(b, &mut prefixes);
- } else {
- break read_0f_opcode(b, &mut prefixes);
- }
} else if let Interpretation::Instruction(_) = record.0 {
break record;
} else {
+ if b == 0x0f {
+ let b = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
+ if b == 0x38 {
+ let b = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
+ break read_0f38_opcode(b, &mut prefixes);
+ } else if b == 0x3a {
+ let b = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
+ break read_0f3a_opcode(b, &mut prefixes);
+ } else {
+ break read_0f_opcode(b, &mut prefixes);
+ }
+ }
// some prefix seen after we saw rex, but before the 0f escape or an actual
// opcode. so we must forget the rex prefix!
// this is to handle sequences like 41660f21cf