Implement depth_first and inverse_depth_first range factory functions.

Also updated as many loops as I could find using df_begin/idf_begin -
strangely I found no uses of idf_begin. Is that just used out of tree?

Also a few places couldn't use df_begin because either they used the
member functions of the depth first iterators or had specific ordering
constraints (I added a comment in the latter case).

Based on a patch by Jim Grosbach. (Jim - you just had iterator_range<T>
where you needed iterator_range<idf_iterator<T>>)

llvm-svn: 206016

2 files changed, 6 insertions, 8 deletions

diff --git a/llvm/lib/Target/ARM64/ARM64ConditionalCompares.cpp b/llvm/lib/Target/ARM64/ARM64ConditionalCompares.cpp
index cefa44ad96a..759e8b7df4f 100644
--- a/llvm/lib/Target/ARM64/ARM64ConditionalCompares.cpp
+++ b/llvm/lib/Target/ARM64/ARM64ConditionalCompares.cpp
@@ -908,7 +908,7 @@ bool ARM64ConditionalCompares::runOnMachineFunction(MachineFunction &MF) {
   // Note that updateDomTree() modifies the children of the DomTree node
   // currently being visited. The df_iterator supports that; it doesn't look at
   // child_begin() / child_end() until after a node has been visited.
-  for (auto *I : make_range(df_begin(DomTree), df_end(DomTree)))
+  for (auto *I : depth_first(DomTree))
     if (tryConvert(I->getBlock()))
       Changed = true;
 
diff --git a/llvm/lib/Target/R600/AMDILCFGStructurizer.cpp b/llvm/lib/Target/R600/AMDILCFGStructurizer.cpp
index 21ca560dba0..1b458df294e 100644
--- a/llvm/lib/Target/R600/AMDILCFGStructurizer.cpp
+++ b/llvm/lib/Target/R600/AMDILCFGStructurizer.cpp
@@ -1075,13 +1075,11 @@ int AMDGPUCFGStructurizer::ifPatternMatch(MachineBasicBlock *MBB) {
 
 int AMDGPUCFGStructurizer::loopendPatternMatch() {
   std::vector<MachineLoop *> NestedLoops;
-  for (MachineLoopInfo::iterator It = MLI->begin(), E = MLI->end();
-      It != E; ++It) {
-    df_iterator<MachineLoop *> LpIt = df_begin(*It),
-        LpE = df_end(*It);
-    for (; LpIt != LpE; ++LpIt)
-      NestedLoops.push_back(*LpIt);
-  }
+  for (MachineLoopInfo::iterator It = MLI->begin(), E = MLI->end(); It != E;
+       ++It)
+    for (MachineLoop *ML : depth_first(*It))
+      NestedLoops.push_back(ML);
+
   if (NestedLoops.size() == 0)
     return 0;