From 9b3c56c0e62c3d1c27ffef4b8021663798b73ca7 Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Sun, 26 Jul 2026 17:56:26 +0000
Subject: thumb: when nonconforming, allow it/cond=1111 like capstone

---
 src/armv7/display.rs | 11 +++++++++--
 src/armv7/thumb.rs   |  9 +++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/armv7/display.rs b/src/armv7/display.rs
index 6f6fba1..d2198de 100644
--- a/src/armv7/display.rs
+++ b/src/armv7/display.rs
@@ -620,8 +620,15 @@ pub(crate) fn visit_inst<T: DisplaySink>(instr: &Instruction, out: &mut T) -> fm
             panic!("impossible it operand");
         };
 
-        let inv = cond & 1 == 1;
-        let condition = ConditionCode::build(*cond as u8);
+        let (inv, condition) = if *cond == 0b1111 {
+            // we've allowed *unpredictable* instruction encodings. capstone calls this condition
+            // "al" as well, so might as well follow along... and for this condition code it
+            // doesn't invert the fields either!
+            (false, ConditionCode::AL)
+        } else {
+            let inv = cond & 1 == 1;
+            (inv, ConditionCode::build(*cond as u8))
+        };
         if mask & 0b0001 != 0 {
             // three flags
             out.write_char(if inv ^ ((mask & 0b1000) != 0) { 'e' } else { 't' })?;
diff --git a/src/armv7/thumb.rs b/src/armv7/thumb.rs
index 7aa3a5d..9e9c30a 100644
--- a/src/armv7/thumb.rs
+++ b/src/armv7/thumb.rs
@@ -3918,8 +3918,13 @@ pub fn decode_into<T: Reader<<ARMv7 as Arch>::Address, <ARMv7 as Arch>::Word>>(d
                     let firstcond = opa;
                     let mask = opb;
                     inst.opcode = Opcode::IT;
-                    if firstcond == 0b1111 {
-                        return Err(DecodeError::InvalidOperand);
+                    if decoder.should_is_must {
+                        // > if firstcond == ‘1111’ ||
+                        // >    (firstcond == ‘1110’ && BitCount(mask) != 1)
+                        // > then UNPREDICTABLE;
+                        if firstcond == 0b1111 {
+                            return Err(DecodeError::Nonconforming);
+                        }
                     }
                     inst.operands = [
                         Operand::Imm32(firstcond),
-- 
cgit v1.1