[llvm] 25ec267 - [PEI] Remove support for register scavenging during forwards frame index elimination

[Jay Foad via llvm-commits]

Author: Jay Foad
Date: 2023-08-04T08:52:15+01:00
New Revision: 25ec2673feeaf5dbf368903018cf6eaa6b66ab11

URL: https://github.com/llvm/llvm-project/commit/25ec2673feeaf5dbf368903018cf6eaa6b66ab11
DIFF: https://github.com/llvm/llvm-project/commit/25ec2673feeaf5dbf368903018cf6eaa6b66ab11.diff

LOG: [PEI] Remove support for register scavenging during forwards frame index elimination

All targets that require register scavenging now use backwards frame
index elimination.

Differential Revision: https://reviews.llvm.org/D156986

Added: 
    

Modified: 
    llvm/docs/ReleaseNotes.rst
    llvm/lib/CodeGen/PrologEpilogInserter.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 794eec738195c5..12ac2be496ada4 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -123,6 +123,10 @@ Changes to the C API
 Changes to the CodeGen infrastructure
 -------------------------------------
 
+* ``PrologEpilogInserter`` no longer supports register scavenging
+  during forwards frame index elimination. Targets should use
+  backwards frame index elimination instead.
+
 Changes to the Metadata Info
 ---------------------------------
 

diff  --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 09ad41aa143c0d..fe88a360e832f3 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -1531,9 +1531,6 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &MF,
   const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo();
   const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
 
-  if (RS && FrameIndexEliminationScavenging)
-    RS->enterBasicBlock(*BB);
-
   bool InsideCallSequence = false;
 
   for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
@@ -1567,8 +1564,7 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &MF,
       // If this instruction has a FrameIndex operand, we need to
       // use that target machine register info object to eliminate
       // it.
-      TRI.eliminateFrameIndex(MI, SPAdj, i,
-                              FrameIndexEliminationScavenging ?  RS : nullptr);
+      TRI.eliminateFrameIndex(MI, SPAdj, i);
 
       // Reset the iterator if we were at the beginning of the BB.
       if (AtBeginning) {
@@ -1590,10 +1586,7 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &MF,
     if (DidFinishLoop && InsideCallSequence)
       SPAdj += TII.getSPAdjust(MI);
 
-    if (DoIncr && I != BB->end()) ++I;
-
-    // Update register states.
-    if (RS && FrameIndexEliminationScavenging && DidFinishLoop)
-      RS->forward(MI);
+    if (DoIncr && I != BB->end())
+      ++I;
   }
 }