From e15ef43a243ae0e0db369cead1786f4f2c4e690e Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Sun, 4 Jul 2021 13:21:09 -0700
Subject: support xacquire/xrelease prefixing

---
 src/long_mode/display.rs | 25 +++++++++++++++++++++++--
 src/long_mode/mod.rs     | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 2 deletions(-)

(limited to 'src/long_mode')

diff --git a/src/long_mode/display.rs b/src/long_mode/display.rs
index 948df53..7f21b35 100644
--- a/src/long_mode/display.rs
+++ b/src/long_mode/display.rs
@@ -3311,8 +3311,14 @@ impl Instruction {
 }
 
 fn contextualize_intel<T: fmt::Write, Y: YaxColors>(instr: &Instruction, colors: &Y, _address: u64, _context: Option<&NoContext>, out: &mut T) -> fmt::Result {
+    if instr.xacquire() {
+        out.write_str("xacquire ")?;
+    }
+    if instr.xrelease() {
+        out.write_str("xrelease ")?;
+    }
     if instr.prefixes.lock() {
-        write!(out, "lock ")?;
+        out.write_str("lock ")?;
     }
 
     if instr.prefixes.rep_any() {
@@ -3423,8 +3429,23 @@ fn contextualize_intel<T: fmt::Write, Y: YaxColors>(instr: &Instruction, colors:
 fn contextualize_c<T: fmt::Write, Y: YaxColors>(instr: &Instruction, _colors: &Y, _address: u64, _context: Option<&NoContext>, out: &mut T) -> fmt::Result {
     let mut brace_count = 0;
 
+    let mut prefixed = false;
+
+    if instr.xacquire() {
+        out.write_str("xacquire ")?;
+        prefixed = true;
+    }
+    if instr.xrelease() {
+        out.write_str("xrelease ")?;
+        prefixed = true;
+    }
     if instr.prefixes.lock() {
-        out.write_str("lock { ")?;
+        out.write_str("lock ")?;
+        prefixed = true;
+    }
+
+    if prefixed {
+        out.write_str("{ ")?;
         brace_count += 1;
     }
 
diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs
index 79f3fee..6e3e21d 100644
--- a/src/long_mode/mod.rs
+++ b/src/long_mode/mod.rs
@@ -4470,6 +4470,48 @@ impl Instruction {
             instr: self,
         }
     }
+
+    /// does this instruction include the `xacquire` hint for hardware lock elision?
+    pub fn xacquire(&self) -> bool {
+        if self.prefixes.repnz() {
+            // xacquire is permitted on typical `lock` instructions, OR `xchg` with memory operand,
+            // regardless of `lock` prefix.
+            if self.prefixes.lock() {
+                true
+            } else if self.opcode == Opcode::XCHG {
+                self.operands[0] != OperandSpec::RegMMM && self.operands[1] != OperandSpec::RegMMM
+            } else {
+                false
+            }
+        } else {
+            false
+        }
+    }
+
+    /// does this instruction include the `xrelease` hint for hardware lock elision?
+    pub fn xrelease(&self) -> bool {
+        if self.prefixes.rep() {
+            // xrelease is permitted on typical `lock` instructions, OR `xchg` with memory operand,
+            // regardless of `lock` prefix. additionally, xrelease is permitted on some forms of mov.
+            if self.prefixes.lock() {
+                true
+            } else if self.opcode == Opcode::XCHG {
+                self.operands[0] != OperandSpec::RegMMM && self.operands[1] != OperandSpec::RegMMM
+            } else if self.opcode == Opcode::MOV {
+                self.operands[0] != OperandSpec::RegMMM && (
+                    self.operands[1] == OperandSpec::RegRRR ||
+                    self.operands[1] == OperandSpec::ImmI8 ||
+                    self.operands[1] == OperandSpec::ImmI16 ||
+                    self.operands[1] == OperandSpec::ImmI32 ||
+                    self.operands[1] == OperandSpec::ImmI64
+                )
+            } else {
+                false
+            }
+        } else {
+            false
+        }
+    }
 }
 
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
-- 
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