[llvm-branch-commits] [llvm] AMDGPU: Remove special case of SGPR_LO class in imm folding (PR #155518)

[Matt Arsenault via llvm-branch-commits]

https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/155518

Previous change accidentally broke this which shows it's not
doing anything.

>From 37c07a590ad6f82d15329729838a9d472d8f591a Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Wed, 27 Aug 2025 08:26:25 +0900
Subject: [PATCH] AMDGPU: Remove special case of SGPR_LO class in imm folding

Previous change accidentally broke this which shows it's not
doing anything.
---
 llvm/lib/Target/AMDGPU/SIFoldOperands.cpp | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index e1bc6d0239111..3979e1e0c44aa 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -1260,14 +1260,6 @@ void SIFoldOperandsImpl::foldOperand(
       return;
 
     const TargetRegisterClass *DestRC = TRI->getRegClassForReg(*MRI, DestReg);
-    // Allow immediates COPYd into sgpr_lo16 to be further folded while
-    // still being legal if not further folded
-    if (DestRC == &AMDGPU::SGPR_LO16RegClass) {
-      assert(ST->useRealTrue16Insts());
-      MRI->setRegClass(DestReg, &AMDGPU::SGPR_32RegClass);
-      DestRC = &AMDGPU::SGPR_32RegClass;
-    }
-
     // In order to fold immediates into copies, we need to change the copy to a
     // MOV. Find a compatible mov instruction with the value.
     for (unsigned MovOp :