[llvm] [M68k] Fix encodings of CAS instructions (PR #154481)

[Sergei Barannikov via llvm-commits]

https://github.com/s-barannikov created https://github.com/llvm/llvm-project/pull/154481

The immediate part of memory operands was not encoded.

>From a6cd8e5ad889c159699d476e6573d3a9f08f30e2 Mon Sep 17 00:00:00 2001
From: Sergei Barannikov <barannikov88 at gmail.com>
Date: Wed, 20 Aug 2025 09:45:09 +0300
Subject: [PATCH] [M68k] Fix encodings of CAS instructions

The immediate part of memory operands was not encoded.
---
 .../M68k/Disassembler/M68kDisassembler.cpp     |  6 ------
 llvm/lib/Target/M68k/M68kInstrAtomics.td       | 11 +++++++----
 llvm/test/MC/M68k/Atomics/cas.s                | 18 +++++++++---------
 3 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp b/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp
index 4ec18fe6bf544..1b304b01dab13 100644
--- a/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp
+++ b/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp
@@ -83,12 +83,6 @@ static DecodeStatus DecodeXR32RegisterClass(MCInst &Inst, uint64_t RegNo,
   return DecodeRegisterClass(Inst, RegNo, Address, Decoder);
 }
 
-static DecodeStatus DecodeXR32RegisterClass(MCInst &Inst, APInt RegNo,
-                                            uint64_t Address,
-                                            const void *Decoder) {
-  return DecodeRegisterClass(Inst, RegNo.getZExtValue(), Address, Decoder);
-}
-
 static DecodeStatus DecodeXR16RegisterClass(MCInst &Inst, uint64_t RegNo,
                                             uint64_t Address,
                                             const void *Decoder) {
diff --git a/llvm/lib/Target/M68k/M68kInstrAtomics.td b/llvm/lib/Target/M68k/M68kInstrAtomics.td
index 867afbefe68fe..b2b64ca853220 100644
--- a/llvm/lib/Target/M68k/M68kInstrAtomics.td
+++ b/llvm/lib/Target/M68k/M68kInstrAtomics.td
@@ -67,7 +67,8 @@ class MxCASARIDOp<bits<2> size_encoding, MxType type>
              "cas."#type.Prefix#" $dc, $du, $mem"> {
   let Inst = (ascend
                 (descend 0b00001, size_encoding, 0b011, MxEncAddrMode_p<"mem">.EA),
-                (descend 0b0000000, (operand "$du", 3), 0b000, (operand "$dc", 3))
+                (descend 0b0000000, (operand "$du", 3), 0b000, (operand "$dc", 3)),
+                MxEncAddrMode_p<"mem">.Supplement
               );
   let Constraints = "$out = $dc";
   let mayLoad = 1;
@@ -84,7 +85,8 @@ class MxCASARIIOp<bits<2> size_encoding, MxType type>
              "cas."#type.Prefix#" $dc, $du, $mem"> {
   let Inst = (ascend
                 (descend 0b00001, size_encoding, 0b011, MxEncAddrMode_f<"mem">.EA),
-                (descend 0b0000000, (operand "$du", 3), 0b000, (operand "$dc", 3))
+                (descend 0b0000000, (operand "$du", 3), 0b000, (operand "$dc", 3)),
+                MxEncAddrMode_f<"mem">.Supplement
               );
   let Constraints = "$out = $dc";
   let mayLoad = 1;
@@ -100,8 +102,9 @@ class MxCASALOp<bits<2> size_encoding, MxType type>
              (ins type.ROp:$dc, type.ROp:$du, !cast<MxMemOp>("MxAL"#type.Size):$mem),
              "cas."#type.Prefix#" $dc, $du, $mem"> {
   let Inst = (ascend
-                (descend 0b00001, size_encoding, 0b011, MxEncAddrMode_abs<"mem">.EA),
-                (descend 0b0000000, (operand "$du", 3), 0b000, (operand "$dc", 3))
+                (descend 0b00001, size_encoding, 0b011, MxEncAddrMode_abs<"mem", true>.EA),
+                (descend 0b0000000, (operand "$du", 3), 0b000, (operand "$dc", 3)),
+                MxEncAddrMode_abs<"mem", true>.Supplement
               );
   let Constraints = "$out = $dc";
   let mayLoad = 1;
diff --git a/llvm/test/MC/M68k/Atomics/cas.s b/llvm/test/MC/M68k/Atomics/cas.s
index c6cae72c03f09..32b210aacb9c5 100644
--- a/llvm/test/MC/M68k/Atomics/cas.s
+++ b/llvm/test/MC/M68k/Atomics/cas.s
@@ -15,39 +15,39 @@ cas.l %d6, %d7, (%a4)
 
 ; Address Register Indirect with Displacement
 ; CHECK: cas.b %d3, %d2, (5,%a2)
-; CHECK-SAME: ; encoding: [0x0a,0xea,0x00,0x83]
+; CHECK-SAME: ; encoding: [0x0a,0xea,0x00,0x83,0x00,0x05]
 cas.b %d3, %d2, (5, %a2)
 
 ; CHECK: cas.w %d4, %d5, (6,%a3)
-; CHECK-SAME: ; encoding: [0x0c,0xeb,0x01,0x44]
+; CHECK-SAME: ; encoding: [0x0c,0xeb,0x01,0x44,0x00,0x06]
 cas.w %d4, %d5, (6, %a3)
 
 ; CHECK: cas.l %d6, %d7, (7,%a4)
-; CHECK-SAME: ; encoding: [0x0e,0xec,0x01,0xc6]
+; CHECK-SAME: ; encoding: [0x0e,0xec,0x01,0xc6,0x00,0x07]
 cas.l %d6, %d7, (7, %a4)
 
 ; Address Register Indirect with Index (Scale = 1)
 ; CHECK: cas.b %d3, %d2, (5,%a2,%d1)
-; CHECK-SAME: ; encoding: [0x0a,0xf2,0x00,0x83]
+; CHECK-SAME: ; encoding: [0x0a,0xf2,0x00,0x83,0x18,0x05]
 cas.b %d3, %d2, (5, %a2, %d1)
 
 ; CHECK: cas.w %d4, %d5, (6,%a3,%d1)
-; CHECK-SAME: ; encoding: [0x0c,0xf3,0x01,0x44]
+; CHECK-SAME: ; encoding: [0x0c,0xf3,0x01,0x44,0x18,0x06]
 cas.w %d4, %d5, (6, %a3, %d1)
 
 ; CHECK: cas.l %d6, %d7, (7,%a4,%d1)
-; CHECK-SAME: ; encoding: [0x0e,0xf4,0x01,0xc6]
+; CHECK-SAME: ; encoding: [0x0e,0xf4,0x01,0xc6,0x18,0x07]
 cas.l %d6, %d7, (7, %a4, %d1)
 
 ; Absolute Long Address
 ; CHECK: cas.b %d3, %d2, $ffffffffffffffff
-; CHECK-SAME: ; encoding: [0x0a,0xf8,0x00,0x83]
+; CHECK-SAME: ; encoding: [0x0a,0xf9,0x00,0x83,0xff,0xff,0xff,0xff]
 cas.b %d3, %d2, $ffffffffffffffff
 
 ; CHECK: cas.w %d4, %d5, $ffffffffffffffff
-; CHECK-SAME: ; encoding: [0x0c,0xf8,0x01,0x44]
+; CHECK-SAME: ; encoding: [0x0c,0xf9,0x01,0x44,0xff,0xff,0xff,0xff]
 cas.w %d4, %d5, $ffffffffffffffff
 
 ; CHECK: cas.l %d6, %d7, $ffffffffffffffff
-; CHECK-SAME: ; encoding: [0x0e,0xf8,0x01,0xc6]
+; CHECK-SAME: ; encoding: [0x0e,0xf9,0x01,0xc6,0xff,0xff,0xff,0xff]
 cas.l %d6, %d7, $ffffffffffffffff