[llvm] [X86] Fix VPMOVPattern folding for extended registers (PR #191760)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon updated https://github.com/llvm/llvm-project/pull/191760

>From 409c83ecbb62e727767df8c3a9ce844f23f34581 Mon Sep 17 00:00:00 2001
From: Qihan Cai <caiqihan021 at hotmail.com>
Date: Mon, 13 Apr 2026 15:25:13 +1000
Subject: [PATCH] [X86] Fix tryCompressVPMOVPattern incorrectly folds extended
 registers into VEX Fixes a problem that tryCompressVPMOVPattern incorrectly
 folds instruction using extended registers into VEX. Introduced relevant
 tests in MIR.

AI Statement: I used AI to write the tests.
Fixes #191304
---
 llvm/lib/Target/X86/X86CompressEVEX.cpp        | 3 +++
 llvm/test/CodeGen/X86/evex-to-vex-compress.mir | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/llvm/lib/Target/X86/X86CompressEVEX.cpp b/llvm/lib/Target/X86/X86CompressEVEX.cpp
index 603fe920fad53..33f1fe4aea767 100644
--- a/llvm/lib/Target/X86/X86CompressEVEX.cpp
+++ b/llvm/lib/Target/X86/X86CompressEVEX.cpp
@@ -237,6 +237,9 @@ static bool tryCompressVPMOVPattern(MachineInstr &MI, MachineBasicBlock &MBB,
       Opc != X86::VPMOVB2MZ128kr && Opc != X86::VPMOVB2MZ256kr)
     return false;
 
+  if (usesExtendedRegister(MI))
+    return false;
+
   Register MaskReg = MI.getOperand(0).getReg();
   Register SrcVecReg = MI.getOperand(1).getReg();
 
diff --git a/llvm/test/CodeGen/X86/evex-to-vex-compress.mir b/llvm/test/CodeGen/X86/evex-to-vex-compress.mir
index 142f07ae6e2b2..b33a1d571c818 100644
--- a/llvm/test/CodeGen/X86/evex-to-vex-compress.mir
+++ b/llvm/test/CodeGen/X86/evex-to-vex-compress.mir
@@ -904,6 +904,10 @@ body: |
   ; CHECK: $eax = VPMOVMSKBYrr                 $ymm0
   $k0 = VPMOVB2MZ256kr                         $ymm0
   $eax = KMOVDrk                               $k0
+  ; CHECK: $k3 = VPMOVB2MZ256kr                $ymm23
+  ; CHECK: $edx = KMOVDrk                      $k3
+  $k3 = VPMOVB2MZ256kr                         $ymm23
+  $edx = KMOVDrk                               $k3
   ; CHECK: $k0 = VPMOVD2MZ256kr                $ymm0
   ; CHECK: $eax = KMOVBrk                      $k0
   ; CHECK: $ebx = KMOVBrk                      $k0
@@ -1789,6 +1793,10 @@ body: |
   ; CHECK: $eax = VPMOVMSKBrr                  $xmm0
   $k0 = VPMOVB2MZ128kr                         $xmm0
   $eax = KMOVWrk                               $k0
+  ; CHECK: $k3 = VPMOVB2MZ128kr                $xmm23
+  ; CHECK: $edx = KMOVWrk                      $k3
+  $k3 = VPMOVB2MZ128kr                         $xmm23
+  $edx = KMOVWrk                               $k3
   ; CHECK: $k0 = VPMOVD2MZ128kr                $xmm0
   ; CHECK: $eax = KMOVBrk                      $k0
   ; CHECK: $ebx = KMOVBrk                      $k0