[llvm] [X86] Fix an assembler bug of CMPCCXADD. (PR #66748)

[Freddy Ye via llvm-commits]

https://github.com/FreddyLeaf created https://github.com/llvm/llvm-project/pull/66748

None

>From 12b5cdffe55ab2d6726d2384290ae386ef525162 Mon Sep 17 00:00:00 2001
From: Freddy Ye <freddy.ye at intel.com>
Date: Tue, 19 Sep 2023 16:16:27 +0800
Subject: [PATCH] [X86] Fix an assembler bug of CMPCCXADD.

---
 llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp | 2 +-
 llvm/test/MC/Disassembler/X86/cmpccxadd-64.txt        | 4 ++++
 llvm/test/MC/X86/cmpccxadd-att-64.s                   | 3 +++
 llvm/test/MC/X86/cmpccxadd-intel-64.s                 | 3 +++
 4 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index be167d674619c86..225b0823fa86f34 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -948,10 +948,10 @@ X86MCCodeEmitter::emitVEXOpcodePrefix(int MemOperand, const MCInst &MI,
     llvm_unreachable("Unexpected form in emitVEXOpcodePrefix!");
   case X86II::MRMDestMem4VOp3CC: {
     //  MemAddr, src1(ModR/M), src2(VEX_4V)
+    Prefix.setR(MI, CurOp++);
     Prefix.setB(MI, MemOperand + X86::AddrBaseReg);
     Prefix.setX(MI, MemOperand + X86::AddrIndexReg);
     CurOp += X86::AddrNumOperands;
-    Prefix.setR(MI, ++CurOp);
     Prefix.set4V(MI, CurOp++);
     break;
   }
diff --git a/llvm/test/MC/Disassembler/X86/cmpccxadd-64.txt b/llvm/test/MC/Disassembler/X86/cmpccxadd-64.txt
index c562ffb5359566d..62420db37f40d79 100644
--- a/llvm/test/MC/Disassembler/X86/cmpccxadd-64.txt
+++ b/llvm/test/MC/Disassembler/X86/cmpccxadd-64.txt
@@ -769,3 +769,7 @@
 # INTEL: cmpzxadd qword ptr [rdx - 1024], r9, r10
 0xc4,0x62,0xa9,0xe4,0x8a,0x00,0xfc,0xff,0xff
 
+# ATT:   cmpbexadd  %ecx, %r8d, (%rip)
+# INTEL: cmpbexadd dword ptr [rip], r8d, ecx
+0xc4,0x62,0x71,0xe6,0x05,0x00,0x00,0x00,0x00
+
diff --git a/llvm/test/MC/X86/cmpccxadd-att-64.s b/llvm/test/MC/X86/cmpccxadd-att-64.s
index a18733d4ef8952c..2ef49cba92e32c0 100644
--- a/llvm/test/MC/X86/cmpccxadd-att-64.s
+++ b/llvm/test/MC/X86/cmpccxadd-att-64.s
@@ -768,3 +768,6 @@
 // CHECK: encoding: [0xc4,0x62,0xa9,0xe4,0x8a,0x00,0xfc,0xff,0xff]
           cmpzxadd  %r10, %r9, -1024(%rdx)
 
+// CHECK: cmpbexadd  %ecx, %r8d, (%rip)
+// CHECK: encoding: [0xc4,0x62,0x71,0xe6,0x05,0x00,0x00,0x00,0x00]
+          cmpbexadd  %ecx, %r8d, (%rip)
diff --git a/llvm/test/MC/X86/cmpccxadd-intel-64.s b/llvm/test/MC/X86/cmpccxadd-intel-64.s
index 1a2d638281eece6..c03873e34deceaa 100644
--- a/llvm/test/MC/X86/cmpccxadd-intel-64.s
+++ b/llvm/test/MC/X86/cmpccxadd-intel-64.s
@@ -768,3 +768,6 @@
 // CHECK: encoding: [0xc4,0x62,0xa9,0xe4,0x8a,0x00,0xfc,0xff,0xff]
           cmpzxadd qword ptr [rdx - 1024], r9, r10
 
+// CHECK: cmpbexadd dword ptr [rip], r8d, ecx
+// CHECK: encoding: [0xc4,0x62,0x71,0xe6,0x05,0x00,0x00,0x00,0x00]
+          cmpbexadd dword ptr [rip], r8d, ecx