[PATCH] D69906: [ARM] Track epilogue instructions with FrameDestroy flag (NFC)

[Oliver Stannard (Linaro) via Phabricator via llvm-commits]

ostannard updated this revision to Diff 250200.
ostannard added a reviewer: efriedma.
ostannard added a comment.
Herald added a subscriber: danielkiss.

- Rebase
- Fix an MIR test


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69906/new/

https://reviews.llvm.org/D69906

Files:
  llvm/lib/Target/ARM/ARMFrameLowering.cpp
  llvm/test/CodeGen/MIR/ARM/thumb2-sub-sp-t3.mir


Index: llvm/test/CodeGen/MIR/ARM/thumb2-sub-sp-t3.mir
===================================================================
--- llvm/test/CodeGen/MIR/ARM/thumb2-sub-sp-t3.mir
+++ llvm/test/CodeGen/MIR/ARM/thumb2-sub-sp-t3.mir
@@ -90,7 +90,7 @@
     ; CHECK: renamable $r0 = t2LDRi12 $sp, 4, 14 /* CC::al */, $noreg :: (dereferenceable load 4 from %ir.s)
     ; CHECK: tBL 14 /* CC::al */, $noreg, @bar, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp
     ; CHECK: $sp = t2ADDspImm12 killed $sp, 4008, 14 /* CC::al */, $noreg
-    ; CHECK: $sp = t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc
+    ; CHECK: $sp = frame-destroy t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc
     renamable $r0 = t2ADDri %stack.0.v, 0, 14, $noreg, $noreg
     t2STRi12 killed renamable $r0, %stack.1.s, 0, 14, $noreg :: (store 4 into %ir.s)
     renamable $r0 = t2LDRi12 %stack.1.s, 0, 14, $noreg :: (dereferenceable load 4 from %ir.s)
Index: llvm/lib/Target/ARM/ARMFrameLowering.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -142,27 +142,6 @@
   return hasReservedCallFrame(MF) || MF.getFrameInfo().hasVarSizedObjects();
 }
 
-static bool isCSRestore(MachineInstr &MI, const ARMBaseInstrInfo &TII,
-                        const MCPhysReg *CSRegs) {
-  // Integer spill area is handled with "pop".
-  if (isPopOpcode(MI.getOpcode())) {
-    // The first two operands are predicates. The last two are
-    // imp-def and imp-use of SP. Check everything in between.
-    for (int i = 5, e = MI.getNumOperands(); i != e; ++i)
-      if (!isCalleeSavedRegister(MI.getOperand(i).getReg(), CSRegs))
-        return false;
-    return true;
-  }
-  if ((MI.getOpcode() == ARM::LDR_POST_IMM ||
-       MI.getOpcode() == ARM::LDR_POST_REG ||
-       MI.getOpcode() == ARM::t2LDR_POST) &&
-      isCalleeSavedRegister(MI.getOperand(0).getReg(), CSRegs) &&
-      MI.getOperand(1).getReg() == ARM::SP)
-    return true;
-
-  return false;
-}
-
 static void emitRegPlusImmediate(
     bool isARM, MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
     const DebugLoc &dl, const ARMBaseInstrInfo &TII, unsigned DestReg,
@@ -796,12 +775,12 @@
       emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes - ArgRegsSaveSize);
   } else {
     // Unwind MBBI to point to first LDR / VLDRD.
-    const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&MF);
     if (MBBI != MBB.begin()) {
       do {
         --MBBI;
-      } while (MBBI != MBB.begin() && isCSRestore(*MBBI, TII, CSRegs));
-      if (!isCSRestore(*MBBI, TII, CSRegs))
+      } while (MBBI != MBB.begin() &&
+               MBBI->getFlag(MachineInstr::FrameDestroy));
+      if (!MBBI->getFlag(MachineInstr::FrameDestroy))
         ++MBBI;
     }
 
@@ -1118,7 +1097,8 @@
     if (Regs.size() > 1 || LdrOpc == 0) {
       MachineInstrBuilder MIB = BuildMI(MBB, MI, DL, TII.get(LdmOpc), ARM::SP)
                                     .addReg(ARM::SP)
-                                    .add(predOps(ARMCC::AL));
+                                    .add(predOps(ARMCC::AL))
+                                    .setMIFlags(MachineInstr::FrameDestroy);
       for (unsigned i = 0, e = Regs.size(); i < e; ++i)
         MIB.addReg(Regs[i], getDefRegState(true));
       if (DeleteRet) {
@@ -1136,7 +1116,8 @@
       MachineInstrBuilder MIB =
         BuildMI(MBB, MI, DL, TII.get(LdrOpc), Regs[0])
           .addReg(ARM::SP, RegState::Define)
-          .addReg(ARM::SP);
+          .addReg(ARM::SP)
+          .setMIFlags(MachineInstr::FrameDestroy);
       // ARM mode needs an extra reg0 here due to addrmode2. Will go away once
       // that refactoring is complete (eventually).
       if (LdrOpc == ARM::LDR_POST_REG || LdrOpc == ARM::LDR_POST_IMM) {


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