[llvm] [BranchFolding] Remove getBranchDebugLoc() (PR #114613)

[Ellis Hoag via llvm-commits]

https://github.com/ellishg created https://github.com/llvm/llvm-project/pull/114613

`getBranchDebugLoc()` was added 12 years ago in https://github.com/llvm/llvm-project/commit/7c5dcb6ccf88582031b93bc0c0e0c2de8a81cc96, before `MachineBasicBlock::findBranchDebugLoc()` was created https://github.com/llvm/llvm-project/commit/06a2128cfa56e0d4954d231b86f44fe04ae8db95 7 years ago. These two functions do almost the same thing, except the later merges debug info from all terminators.

>From d49d2187085f1f43ead549ffde269a9457ee1fe6 Mon Sep 17 00:00:00 2001
From: Ellis Hoag <ellis.sparky.hoag at gmail.com>
Date: Fri, 1 Nov 2024 15:03:18 -0700
Subject: [PATCH] [BranchFolding] Remove getBranchDebugLoc()

---
 llvm/lib/CodeGen/BranchFolding.cpp | 42 ++++++++++++------------------
 1 file changed, 17 insertions(+), 25 deletions(-)

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index f8de13650680a8..384df281c0442b 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -1266,15 +1266,6 @@ static bool IsBetterFallthrough(MachineBasicBlock *MBB1,
   return MBB2I->isCall() && !MBB1I->isCall();
 }
 
-/// getBranchDebugLoc - Find and return, if any, the DebugLoc of the branch
-/// instructions on the block.
-static DebugLoc getBranchDebugLoc(MachineBasicBlock &MBB) {
-  MachineBasicBlock::iterator I = MBB.getLastNonDebugInstr();
-  if (I != MBB.end() && I->isBranch())
-    return I->getDebugLoc();
-  return DebugLoc();
-}
-
 static void copyDebugInfoToPredecessor(const TargetInstrInfo *TII,
                                        MachineBasicBlock &MBB,
                                        MachineBasicBlock &PredMBB) {
@@ -1401,11 +1392,11 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
     // destination, remove the branch, replacing it with an unconditional one or
     // a fall-through.
     if (PriorTBB && PriorTBB == PriorFBB) {
-      DebugLoc dl = getBranchDebugLoc(PrevBB);
+      auto Dl = PrevBB.findBranchDebugLoc();
       TII->removeBranch(PrevBB);
       PriorCond.clear();
       if (PriorTBB != MBB)
-        TII->insertBranch(PrevBB, PriorTBB, nullptr, PriorCond, dl);
+        TII->insertBranch(PrevBB, PriorTBB, nullptr, PriorCond, Dl);
       MadeChange = true;
       ++NumBranchOpts;
       goto ReoptimizeBlock;
@@ -1459,9 +1450,9 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
     // If the prior block branches somewhere else on the condition and here if
     // the condition is false, remove the uncond second branch.
     if (PriorFBB == MBB) {
-      DebugLoc dl = getBranchDebugLoc(PrevBB);
+      auto Dl = PrevBB.findBranchDebugLoc();
       TII->removeBranch(PrevBB);
-      TII->insertBranch(PrevBB, PriorTBB, nullptr, PriorCond, dl);
+      TII->insertBranch(PrevBB, PriorTBB, nullptr, PriorCond, Dl);
       MadeChange = true;
       ++NumBranchOpts;
       goto ReoptimizeBlock;
@@ -1473,9 +1464,9 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
     if (PriorTBB == MBB) {
       SmallVector<MachineOperand, 4> NewPriorCond(PriorCond);
       if (!TII->reverseBranchCondition(NewPriorCond)) {
-        DebugLoc dl = getBranchDebugLoc(PrevBB);
+        auto Dl = PrevBB.findBranchDebugLoc();
         TII->removeBranch(PrevBB);
-        TII->insertBranch(PrevBB, PriorFBB, nullptr, NewPriorCond, dl);
+        TII->insertBranch(PrevBB, PriorFBB, nullptr, NewPriorCond, Dl);
         MadeChange = true;
         ++NumBranchOpts;
         goto ReoptimizeBlock;
@@ -1511,9 +1502,9 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
           LLVM_DEBUG(dbgs() << "\nMoving MBB: " << *MBB
                             << "To make fallthrough to: " << *PriorTBB << "\n");
 
-          DebugLoc dl = getBranchDebugLoc(PrevBB);
+          auto Dl = PrevBB.findBranchDebugLoc();
           TII->removeBranch(PrevBB);
-          TII->insertBranch(PrevBB, MBB, nullptr, NewPriorCond, dl);
+          TII->insertBranch(PrevBB, MBB, nullptr, NewPriorCond, Dl);
 
           // Move this block to the end of the function.
           MBB->moveAfter(&MF.back());
@@ -1574,9 +1565,9 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
     if (CurTBB && CurFBB && CurFBB == MBB && CurTBB != MBB) {
       SmallVector<MachineOperand, 4> NewCond(CurCond);
       if (!TII->reverseBranchCondition(NewCond)) {
-        DebugLoc dl = getBranchDebugLoc(*MBB);
+        auto Dl = MBB->findBranchDebugLoc();
         TII->removeBranch(*MBB);
-        TII->insertBranch(*MBB, CurFBB, CurTBB, NewCond, dl);
+        TII->insertBranch(*MBB, CurFBB, CurTBB, NewCond, Dl);
         MadeChange = true;
         ++NumBranchOpts;
         goto ReoptimizeBlock;
@@ -1588,7 +1579,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
     if (CurTBB && CurCond.empty() && !CurFBB &&
         IsBranchOnlyBlock(MBB) && CurTBB != MBB &&
         !MBB->hasAddressTaken() && !MBB->isEHPad()) {
-      DebugLoc dl = getBranchDebugLoc(*MBB);
+      auto Dl = MBB->findBranchDebugLoc();
       // This block may contain just an unconditional branch.  Because there can
       // be 'non-branch terminators' in the block, try removing the branch and
       // then seeing if the block is empty.
@@ -1622,9 +1613,9 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
               assert(!PriorFBB && "Machine CFG out of date!");
               PriorFBB = MBB;
             }
-            DebugLoc pdl = getBranchDebugLoc(PrevBB);
+            auto PrevDl = PrevBB.findBranchDebugLoc();
             TII->removeBranch(PrevBB);
-            TII->insertBranch(PrevBB, PriorTBB, PriorFBB, PriorCond, pdl);
+            TII->insertBranch(PrevBB, PriorTBB, PriorFBB, PriorCond, PrevDl);
           }
 
           // Iterate through all the predecessors, revectoring each in-turn.
@@ -1657,10 +1648,11 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
               bool NewCurUnAnalyzable = TII->analyzeBranch(
                   *PMBB, NewCurTBB, NewCurFBB, NewCurCond, true);
               if (!NewCurUnAnalyzable && NewCurTBB && NewCurTBB == NewCurFBB) {
-                DebugLoc pdl = getBranchDebugLoc(*PMBB);
+                auto PrevDl = PMBB->findBranchDebugLoc();
                 TII->removeBranch(*PMBB);
                 NewCurCond.clear();
-                TII->insertBranch(*PMBB, NewCurTBB, nullptr, NewCurCond, pdl);
+                TII->insertBranch(*PMBB, NewCurTBB, nullptr, NewCurCond,
+                                  PrevDl);
                 MadeChange = true;
                 ++NumBranchOpts;
               }
@@ -1679,7 +1671,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
       }
 
       // Add the branch back if the block is more than just an uncond branch.
-      TII->insertBranch(*MBB, CurTBB, nullptr, CurCond, dl);
+      TII->insertBranch(*MBB, CurTBB, nullptr, CurCond, Dl);
     }
   }