[llvm] e38f98f - [AMDGPU][Scheduler] Fix usage of `TII.reMaterialize` (NFC) (#150259)

[via llvm-commits]

Author: Lucas Ramirez
Date: 2025-07-25T12:51:21+02:00
New Revision: e38f98f535f6e2ce2b42ea0413919f87b1239964

URL: https://github.com/llvm/llvm-project/commit/e38f98f535f6e2ce2b42ea0413919f87b1239964
DIFF: https://github.com/llvm/llvm-project/commit/e38f98f535f6e2ce2b42ea0413919f87b1239964.diff

LOG: [AMDGPU][Scheduler] Fix usage of `TII.reMaterialize` (NFC) (#150259)

Any non-zero `SubIdx` passed to the method is composed with the
rematerialized instruction's first operand's subregister to determine
the new register's subregister. In our case we want the new register to
have the same subregister as the old one, so we should pass 0.

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
index a6553083d722b..3c3247a4a17c5 100644
--- a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -1911,14 +1911,12 @@ void PreRARematStage::rematerialize() {
   for (auto &[DefMI, Remat] : Rematerializations) {
     MachineBasicBlock::iterator InsertPos(Remat.UseMI);
     Register Reg = DefMI->getOperand(0).getReg();
-    unsigned SubReg = DefMI->getOperand(0).getSubReg();
     unsigned DefRegion = MIRegion.at(DefMI);
 
     // Rematerialize DefMI to its use block.
-    TII->reMaterialize(*InsertPos->getParent(), InsertPos, Reg, SubReg, *DefMI,
+    TII->reMaterialize(*InsertPos->getParent(), InsertPos, Reg, 0, *DefMI,
                        *DAG.TRI);
     Remat.RematMI = &*std::prev(InsertPos);
-    Remat.RematMI->getOperand(0).setSubReg(SubReg);
     DAG.LIS->InsertMachineInstrInMaps(*Remat.RematMI);
 
     // Update region boundaries in regions we sinked from (remove defining MI)
@@ -2064,14 +2062,12 @@ void PreRARematStage::finalizeGCNSchedStage() {
     MachineBasicBlock::iterator InsertPos(DAG.Regions[DefRegion].second);
     MachineBasicBlock *MBB = RegionBB[DefRegion];
     Register Reg = RematMI.getOperand(0).getReg();
-    unsigned SubReg = RematMI.getOperand(0).getSubReg();
 
     // Re-rematerialize MI at the end of its original region. Note that it may
     // not be rematerialized exactly in the same position as originally within
     // the region, but it should not matter much.
-    TII->reMaterialize(*MBB, InsertPos, Reg, SubReg, RematMI, *DAG.TRI);
+    TII->reMaterialize(*MBB, InsertPos, Reg, 0, RematMI, *DAG.TRI);
     MachineInstr *NewMI = &*std::prev(InsertPos);
-    NewMI->getOperand(0).setSubReg(SubReg);
     DAG.LIS->InsertMachineInstrInMaps(*NewMI);
 
     auto UseRegion = MIRegion.find(Remat.UseMI);