[CodeGen] Set FrameSetup/FrameDestroy on BUNDLE instructions

[bjope]

Summary

If any of the bundled instructions are marked as FrameSetup
or FrameDestroy, then that property is set on the BUNDLE
instruction as well.

As long as the scheduler/packetizer aren't mixing
prologue/epilogue instructions (i.e. all the bundled
instructions have the same property) then this simply gives
the bundle the correct property (so when using a bundle
iterator in late passes a bundle will be correctly identified
as FrameSetup/FrameDestroy).

When for example bundling a mix of FrameSetup instructions
with non-FrameSetup instructions it could be discussed if
the bundle should have the property or not. The choice here
has been to set these properties on the BUNDLE instruction if
any of the bundled instructions have the property set.

[vsk]

Not having worked in this area I can't give an official lgtm, but this seems reasonable to me.

lib/CodeGen/MachineInstrBundle.cpp

void llvm::finalizeBundle(MachineBasicBlock &MBB,
   SmallSet<unsigned, 32> LocalDefSet;
   SmallSet<unsigned, 8> DeadDefSet;
   SmallSet<unsigned, 16> KilledDefSet;
   SmallVector<unsigned, 8> ExternUses;
   SmallSet<unsigned, 8> ExternUseSet;
   SmallSet<unsigned, 8> KilledUseSet;
   SmallSet<unsigned, 8> UndefUseSet;
   SmallVector<MachineOperand*, 4> Defs;
-  for (; FirstMI != LastMI; ++FirstMI) {
-    for (unsigned i = 0, e = FirstMI->getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = FirstMI->getOperand(i);
+  for (auto MII = FirstMI; MII != LastMI; ++MII) {
+    for (unsigned i = 0, e = MII->getNumOperands(); i != e; ++i) {
+      MachineOperand &MO = MII->getOperand(i);
       if (!MO.isReg())
         continue;
       if (MO.isDef()) {
         Defs.push_back(&MO);
         continue;
       }
 
       unsigned Reg = MO.getReg();
void llvm::finalizeBundle(MachineBasicBlock &MBB,
 
   for (unsigned i = 0, e = ExternUses.size(); i != e; ++i) {
     unsigned Reg = ExternUses[i];
     bool isKill = KilledUseSet.count(Reg);
     bool isUndef = UndefUseSet.count(Reg);
     MIB.addReg(Reg, getKillRegState(isKill) | getUndefRegState(isUndef) |
                getImplRegState(true));
   }
+
+  // Set FrameSetup/FrameDestroy for the bundle. If any of the instructions got
+  // the property, then also set it on the bundle.
+  for (auto MII = FirstMI; MII != LastMI; ++MII) {
+    if (MII->getFlag(MachineInstr::FrameSetup))
+      MIB.setMIFlag(MachineInstr::FrameSetup);
+    if (MII->getFlag(MachineInstr::FrameDestroy))
+      MIB.setMIFlag(MachineInstr::FrameDestroy);
+  }
 }
 
 /// finalizeBundle - Same functionality as the previous finalizeBundle except
 /// the last instruction in the bundle is not provided as an input. This is
 /// used in cases where bundles are pre-determined by marking instructions
 /// with 'InsideBundle' marker. It returns the MBB instruction iterator that
 /// points to the end of the bundle.
 MachineBasicBlock::instr_iterator

test/CodeGen/Hexagon/packetize-frame-setup-destroy.mir

+# RUN: llc -march=hexagon -run-pass hexagon-packetizer %s -o - | FileCheck %s
+
+##############################################################################
+# This test case is not really hexagon specific, but we use hexagon to get
+# bundling.
+#
+# The goal is to verify that the BUNDLE instruction is getting the
+# frame-setup/frame-destroy attribute if any of the bundled instructions got
+# the attribute.
+##############################################################################
+
+---
+name: setup
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $r1, $r2
+    successors: %bb.1
+    $r3 = frame-setup L2_loadri_io $r1, 0
+    J4_cmpgtu_f_jumpnv_t killed $r3, killed $r2, %bb.1, implicit-def $pc
+
+  bb.1:
+...
+
+# CHECK-LABEL: name: setup
+# CHECK: frame-setup BUNDLE
+
+##############################################################################
+
+---
+name: destroy
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $r1, $r2
+    successors: %bb.1
+    $r3 = frame-destroy L2_loadri_io $r1, 0
+    J4_cmpgtu_f_jumpnv_t killed $r3, killed $r2, %bb.1, implicit-def $pc
+
+  bb.1:
+...
+
+# CHECK-LABEL: name: destroy
+# CHECK: frame-destroy BUNDLE
+
+##############################################################################
+
+---
+name: mixed
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $r1, $r2
+    successors: %bb.1
+    $r3 = frame-setup L2_loadri_io $r1, 0
+    frame-destroy J4_cmpgtu_f_jumpnv_t killed $r3, killed $r2, %bb.1, implicit-def $pc
+
+  bb.1:
+...
+
+# CHECK-LABEL: name: mixed
+# CHECK: frame-setup frame-destroy BUNDLE