From f04aae61fa55c59956e75d4a6fd68b2530f1a1fe Mon Sep 17 00:00:00 2001
From: Sanjoy Das <sanjoy@playingwithpointers.com>
Date: Sun, 25 Oct 2015 19:08:32 +0000
Subject: [PATCH] [LCSSA] Use range for loops; NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251248 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/LCSSA.cpp | 49 ++++++++++++++++++------------------------
 1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index de1a62c1fb1..178c3fe885d 100644
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -104,10 +104,7 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
 
   // Insert the LCSSA phi's into all of the exit blocks dominated by the
   // value, and add them to the Phi's map.
-  for (SmallVectorImpl<BasicBlock *>::const_iterator BBI = ExitBlocks.begin(),
-                                                     BBE = ExitBlocks.end();
-       BBI != BBE; ++BBI) {
-    BasicBlock *ExitBB = *BBI;
+  for (BasicBlock *ExitBB : ExitBlocks) {
     if (!DT.dominates(DomNode, DT.getNode(ExitBB)))
       continue;
 
@@ -151,26 +148,26 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
 
   // Rewrite all uses outside the loop in terms of the new PHIs we just
   // inserted.
-  for (unsigned i = 0, e = UsesToRewrite.size(); i != e; ++i) {
+  for (Use *UseToRewrite : UsesToRewrite) {
     // If this use is in an exit block, rewrite to use the newly inserted PHI.
     // This is required for correctness because SSAUpdate doesn't handle uses in
     // the same block.  It assumes the PHI we inserted is at the end of the
     // block.
-    Instruction *User = cast<Instruction>(UsesToRewrite[i]->getUser());
+    Instruction *User = cast<Instruction>(UseToRewrite->getUser());
     BasicBlock *UserBB = User->getParent();
     if (PHINode *PN = dyn_cast<PHINode>(User))
-      UserBB = PN->getIncomingBlock(*UsesToRewrite[i]);
+      UserBB = PN->getIncomingBlock(*UseToRewrite);
 
     if (isa<PHINode>(UserBB->begin()) && isExitBlock(UserBB, ExitBlocks)) {
       // Tell the VHs that the uses changed. This updates SCEV's caches.
-      if (UsesToRewrite[i]->get()->hasValueHandle())
-        ValueHandleBase::ValueIsRAUWd(*UsesToRewrite[i], &UserBB->front());
-      UsesToRewrite[i]->set(&UserBB->front());
+      if (UseToRewrite->get()->hasValueHandle())
+        ValueHandleBase::ValueIsRAUWd(*UseToRewrite, &UserBB->front());
+      UseToRewrite->set(&UserBB->front());
       continue;
     }
 
     // Otherwise, do full PHI insertion.
-    SSAUpdate.RewriteUse(*UsesToRewrite[i]);
+    SSAUpdate.RewriteUse(*UseToRewrite);
   }
 
   // Post process PHI instructions that were inserted into another disjoint loop
@@ -193,10 +190,9 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
   }
 
   // Remove PHI nodes that did not have any uses rewritten.
-  for (unsigned i = 0, e = AddedPHIs.size(); i != e; ++i) {
-    if (AddedPHIs[i]->use_empty())
-      AddedPHIs[i]->eraseFromParent();
-  }
+  for (PHINode *PN : AddedPHIs)
+    if (PN->use_empty())
+      PN->eraseFromParent();
 
   return true;
 }
@@ -208,8 +204,8 @@ blockDominatesAnExit(BasicBlock *BB,
                      DominatorTree &DT,
                      const SmallVectorImpl<BasicBlock *> &ExitBlocks) {
   DomTreeNode *DomNode = DT.getNode(BB);
-  for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
-    if (DT.dominates(DomNode, DT.getNode(ExitBlocks[i])))
+  for (BasicBlock *ExitBB : ExitBlocks)
+    if (DT.dominates(DomNode, DT.getNode(ExitBB)))
       return true;
 
   return false;
@@ -230,25 +226,22 @@ bool llvm::formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI,
 
   // Look at all the instructions in the loop, checking to see if they have uses
   // outside the loop.  If so, rewrite those uses.
-  for (Loop::block_iterator BBI = L.block_begin(), BBE = L.block_end();
-       BBI != BBE; ++BBI) {
-    BasicBlock *BB = *BBI;
-
+  for (BasicBlock *BB : L.blocks()) {
     // For large loops, avoid use-scanning by using dominance information:  In
     // particular, if a block does not dominate any of the loop exits, then none
     // of the values defined in the block could be used outside the loop.
     if (!blockDominatesAnExit(BB, DT, ExitBlocks))
       continue;
 
-    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+    for (Instruction &I : *BB) {
       // Reject two common cases fast: instructions with no uses (like stores)
       // and instructions with one use that is in the same block as this.
-      if (I->use_empty() ||
-          (I->hasOneUse() && I->user_back()->getParent() == BB &&
-           !isa<PHINode>(I->user_back())))
+      if (I.use_empty() ||
+          (I.hasOneUse() && I.user_back()->getParent() == BB &&
+           !isa<PHINode>(I.user_back())))
         continue;
 
-      Changed |= processInstruction(L, *I, DT, ExitBlocks, PredCache, LI);
+      Changed |= processInstruction(L, I, DT, ExitBlocks, PredCache, LI);
     }
   }
 
@@ -269,8 +262,8 @@ bool llvm::formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
   bool Changed = false;
 
   // Recurse depth-first through inner loops.
-  for (Loop::iterator I = L.begin(), E = L.end(); I != E; ++I)
-    Changed |= formLCSSARecursively(**I, DT, LI, SE);
+  for (Loop *L : L.getSubLoops())
+    Changed |= formLCSSARecursively(*L, DT, LI, SE);
 
   Changed |= formLCSSA(L, DT, LI, SE);
   return Changed;
-- 
2.11.0