[BlockPlacement] Add option to align all non-fall-through blocks.
Summary: This option is being added for testing purposes.
Reviewers: mcrosier
Subscribers: mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D16410
llvm-svn: 258409
diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
index f5e3056..ce920a1 100644
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -62,6 +62,13 @@
"blocks in the function."),
cl::init(0), cl::Hidden);
+static cl::opt<unsigned> AlignAllNonFallThruBlocks(
+ "align-all-nofallthru-blocks",
+ cl::desc("Force the alignment of all "
+ "blocks that have no fall-through predecessors (i.e. don't add "
+ "nops that are executed)."),
+ cl::init(0), cl::Hidden);
+
static cl::opt<unsigned>
AlignAllLoops("align-all-loops",
cl::desc("Force the alignment of all loops in the function."),
@@ -1405,6 +1412,15 @@
// Align all of the blocks in the function to a specific alignment.
for (MachineBasicBlock &MBB : F)
MBB.setAlignment(AlignAllBlock);
+ else if (AlignAllNonFallThruBlocks) {
+ // Align all of the blocks that have no fall-through predecessors to a
+ // specific alignment.
+ for (auto MBI = std::next(F.begin()), MBE = F.end(); MBI != MBE; ++MBI) {
+ auto LayoutPred = std::prev(MBI);
+ if (!LayoutPred->isSuccessor(&*MBI))
+ MBI->setAlignment(AlignAllNonFallThruBlocks);
+ }
+ }
// We always return true as we have no way to track whether the final order
// differs from the original order.