[mem2reg] Use range loops (NFCI)

Summary:
Several for loops in PromoteMemoryToRegister.cpp leave their increment
expression empty, instead incrementing the iterator within the for loop
body. I believe this is because these loops were previously implemented
as while loops; see https://reviews.llvm.org/rL188327.

Incrementing the iterator within the body of the for loop instead of
in its increment expression makes it seem like the iterator will be
modified or conditionally incremented within the loop, but that is not
the case in these loops.

Instead, use range loops.

Test Plan: `check-llvm`

Reviewers: davide, bkramer

Reviewed By: davide, bkramer

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D43473

llvm-svn: 325532

1 files changed, 8 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
index fcd3bd08482..ac85cafb268 100644
--- a/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ b/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -136,8 +136,8 @@ struct AllocaInfo {
     // As we scan the uses of the alloca instruction, keep track of stores,
     // and decide whether all of the loads and stores to the alloca are within
     // the same basic block.
-    for (auto UI = AI->user_begin(), E = AI->user_end(); UI != E;) {
-      Instruction *User = cast<Instruction>(*UI++);
+    for (User *U : AI->users()) {
+      Instruction *User = cast<Instruction>(U);
 
       if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
         // Remember the basic blocks which define new values for the alloca
@@ -325,9 +325,8 @@ static void removeLifetimeIntrinsicUsers(AllocaInst *AI) {
   // Knowing that this alloca is promotable, we know that it's safe to kill all
   // instructions except for load and store.
 
-  for (auto UI = AI->user_begin(), UE = AI->user_end(); UI != UE;) {
-    Instruction *I = cast<Instruction>(*UI);
-    ++UI;
+  for (User *U : AI->users()) {
+    Instruction *I = cast<Instruction>(U);
     if (isa<LoadInst>(I) || isa<StoreInst>(I))
       continue;
 
@@ -364,8 +363,8 @@ static bool rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info,
   // Clear out UsingBlocks.  We will reconstruct it here if needed.
   Info.UsingBlocks.clear();
 
-  for (auto UI = AI->user_begin(), E = AI->user_end(); UI != E;) {
-    Instruction *UserInst = cast<Instruction>(*UI++);
+  for (User *U : AI->users()) {
+    Instruction *UserInst = cast<Instruction>(U);
     if (!isa<LoadInst>(UserInst)) {
       assert(UserInst == OnlyStore && "Should only have load/stores");
       continue;
@@ -479,8 +478,8 @@ static bool promoteSingleBlockAlloca(AllocaInst *AI, const AllocaInfo &Info,
 
   // Walk all of the loads from this alloca, replacing them with the nearest
   // store above them, if any.
-  for (auto UI = AI->user_begin(), E = AI->user_end(); UI != E;) {
-    LoadInst *LI = dyn_cast<LoadInst>(*UI++);
+  for (User *U : AI->users()) {
+    LoadInst *LI = dyn_cast<LoadInst>(U);
     if (!LI)
       continue;