From e433752d59c1bb790c2de86f2b5e327de8de793d Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Sun, 9 Aug 2020 00:47:02 -0700
Subject: avoid a bunch of checks in the likely display path

rep_any will get speculated `false` quite quickly, whereas checking if
the opcode is a string instruction will be costly no matter what. in the
rare case rep_any is true, i don't care how costly displaying the
instruction is - string instructions are relatively rare, and rep movs
is typically not more than one instance when it shows up.
---
 src/long_mode/display.rs | 20 ++++++++++----------
 src/long_mode/mod.rs     |  2 ++
 2 files changed, 12 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/long_mode/display.rs b/src/long_mode/display.rs
index 42d3683..5dac6cf 100644
--- a/src/long_mode/display.rs
+++ b/src/long_mode/display.rs
@@ -2244,18 +2244,18 @@ impl <T: fmt::Write, Color: fmt::Display, Y: YaxColors<Color>> ShowContextual<u6
             write!(out, "lock ")?;
         }
 
-        /*
-        if [Opcode::MOVS, Opcode::CMPS, Opcode::LODS, Opcode::STOS, Opcode::INS, Opcode::OUTS].contains(&self.opcode) {
-            // only a few of you actually use the prefix...
-            if self.prefixes.rep() {
-                write!(out, "rep ")?;
-            } else if self.prefixes.repz() {
-                write!(out, "repz ")?;
-            } else if self.prefixes.repnz() {
-                write!(out, "repnz ")?;
+        if self.prefixes.rep_any() {
+            if [Opcode::MOVS, Opcode::CMPS, Opcode::LODS, Opcode::STOS, Opcode::INS, Opcode::OUTS].contains(&self.opcode) {
+                // only a few of you actually use the prefix...
+                if self.prefixes.rep() {
+                    write!(out, "rep ")?;
+                } else if self.prefixes.repz() {
+                    write!(out, "repz ")?;
+                } else if self.prefixes.repnz() {
+                    write!(out, "repnz ")?;
+                }
             }
         }
-        */
 
         out.write_str(self.opcode.name())?;
 
diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs
index 3b3bddb..5c431b4 100644
--- a/src/long_mode/mod.rs
+++ b/src/long_mode/mod.rs
@@ -3223,6 +3223,8 @@ impl Prefixes {
     #[inline]
     fn set_repnz(&mut self) { self.bits = (self.bits & 0xcf) | 0x30 }
     #[inline]
+    pub fn rep_any(&self) -> bool { self.bits & 0x30 != 0x00 }
+    #[inline]
     fn operand_size(&self) -> bool { self.bits & 0x1 == 1 }
     #[inline]
     fn set_operand_size(&mut self) { self.bits = self.bits | 0x1 }
-- 
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