Extend BasicBlock sections to allow specifying clusters of basic blocks

in the same section.

This allows specifying BasicBlock clusters like the following example:
!foo
!!0 1 2
!!4
This places basic blocks 0, 1, and 2 in one section in this order, and
places basic block #4 in a single section of its own.

1 files changed, 16 insertions, 26 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index 1b89333..464f389 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -340,32 +340,6 @@ void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
   MBBNumbering.resize(BlockNo);
 }
 
-/// This sets the section ranges of cold or exception section with basic block
-/// sections.
-void MachineFunction::setSectionRange() {
-  // Compute the Section Range of cold and exception basic blocks.  Find the
-  // first and last block of each range.
-  auto SectionRange =
-      ([&](llvm::MachineBasicBlockSection S) -> std::pair<int, int> {
-        auto MBBP =
-            std::find_if(begin(), end(), [&](MachineBasicBlock &MBB) -> bool {
-              return MBB.getSectionType() == S;
-            });
-        if (MBBP == end())
-          return std::make_pair(-1, -1);
-
-        auto MBBQ =
-            std::find_if(rbegin(), rend(), [&](MachineBasicBlock &MBB) -> bool {
-              return MBB.getSectionType() == S;
-            });
-        assert(MBBQ != rend() && "Section end not found!");
-        return std::make_pair(MBBP->getNumber(), MBBQ->getNumber());
-      });
-
-  ExceptionSectionRange = SectionRange(MBBS_Exception);
-  ColdSectionRange = SectionRange(llvm::MBBS_Cold);
-}
-
 /// This is used with -fbasicblock-sections or -fbasicblock-labels option.
 /// A unary encoding of basic block labels is done to keep ".strtab" sizes
 /// small.
@@ -393,6 +367,22 @@ void MachineFunction::createBBLabels() {
   }
 }
 
+/// This method iterates over the basic blocks and assigns their IsBeginSection
+/// and IsEndSection fields. This must be called after MBB layout is finalized
+/// and the SectionID's are assigned to MBBs.
+void MachineFunction::assignBeginEndSections() {
+  front().setIsBeginSection();
+  auto CurrentSectionID = front().getSectionID();
+  for (auto MBBI = std::next(begin()), E = end(); MBBI != E; ++MBBI) {
+    if (MBBI->getSectionID() == CurrentSectionID)
+      continue;
+    MBBI->setIsBeginSection();
+    std::prev(MBBI)->setIsEndSection();
+    CurrentSectionID = MBBI->getSectionID();
+  }
+  back().setIsEndSection();
+}
+
 /// Allocate a new MachineInstr. Use this instead of `new MachineInstr'.
 MachineInstr *MachineFunction::CreateMachineInstr(const MCInstrDesc &MCID,
                                                   const DebugLoc &DL,