[ARM][Thumb2] Mark BTI-clearing instructions as scheduling region boundaries

llvm/lib/Target/ARM/Thumb2InstrInfo.cpp

@@ -286,6 +286,25 @@ MachineInstr *Thumb2InstrInfo::commuteInstructionImpl(MachineInstr &MI,
   return ARMBaseInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2);
 }
 
+bool Thumb2InstrInfo::isSchedulingBoundary(const MachineInstr &MI,
+                                           const MachineBasicBlock *MBB,
+                                           const MachineFunction &MF) const {
+  // BTI clearing instructions shall not take part in scheduling regions as
+  // they must stay in their intended place. Although PAC isn't BTI clearing,
+  // it can be transformed into PACBTI after the pre-RA Machine Scheduling
+  // has taken place, so its movement must also be restricted.
+  switch (MI.getOpcode()) {
+  case ARM::t2BTI:
+  case ARM::t2PAC:
+  case ARM::t2PACBTI:
+  case ARM::t2SG:
+    return true;
+  default:
+    break;
+  }
+  return ARMBaseInstrInfo::isSchedulingBoundary(MI, MBB, MF);
+}
+
 void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator &MBBI,
                                   const DebugLoc &dl, Register DestReg,

llvm/lib/Target/ARM/Thumb2InstrInfo.h

@@ -68,6 +68,10 @@ class Thumb2InstrInfo : public ARMBaseInstrInfo {
                                        unsigned OpIdx1,
                                        unsigned OpIdx2) const override;
 
+  bool isSchedulingBoundary(const MachineInstr &MI,
+                            const MachineBasicBlock *MBB,
+                            const MachineFunction &MF) const override;
+
 private:
   void expandLoadStackGuard(MachineBasicBlock::iterator MI) const override;
 };

llvm/test/CodeGen/ARM/misched-branch-targets.mir

@@ -0,0 +1,166 @@
+# RUN: llc -o - -run-pass=machine-scheduler -misched=shuffle %s | FileCheck %s
+# RUN: llc -o - -run-pass=postmisched %s | FileCheck %s
+
+--- |
+  target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+  target triple = "thumbv8.1m.main-arm-none-eabi"
+
+  define i32 @foo_bti() #0 {
+  entry:
+    ret i32 0
+  }
+
+  define i32 @foo_pac() #0 {
+  entry:
+    ret i32 0
+  }
+
+  define i32 @foo_pacbti() #0 {
+  entry:
+    ret i32 0
+  }
+
+  define i32 @foo_setjmp() #0 {
+  entry:
+    ret i32 0
+  if.then:
+    ret i32 0
+  }
+
+  define i32 @foo_sg() #0 {
+  entry:
+    ret i32 0
+  }
+
+  declare i32 @setjmp(ptr noundef) #1
+  declare void @longjmp(ptr noundef, i32 noundef) #2
+
+  attributes #0 = { "frame-pointer"="all" "target-cpu"="cortex-m55" "target-features"="+armv8.1-m.main" }
+  attributes #1 = { nounwind returns_twice "frame-pointer"="all" "target-cpu"="cortex-m55" "target-features"="+armv8.1-m.main" }
+  attributes #2 = { noreturn nounwind "frame-pointer"="all" "target-cpu"="cortex-m55" "target-features"="+armv8.1-m.main" }
+
+...
+---
+name:            foo_bti
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $r0
+
+    t2BTI
+    renamable $r0, dead $cpsr = nsw tADDi8 killed renamable $r0, 1, 14 /* CC::al */, $noreg
+    tBX_RET 14 /* CC::al */, $noreg, implicit killed $r0
+
+...
+
+# CHECK-LABEL: name:            foo_bti
+# CHECK:       body:
+# CHECK-NEXT:   bb.0.entry:
+# CHECK-NEXT:     liveins: $r0
+# CHECK-NEXT:     {{^ +$}}
+# CHECK-NEXT:     t2BTI
+
+---
+name:            foo_pac
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $r0, $lr, $r12
+
+    frame-setup t2PAC implicit-def $r12, implicit $lr, implicit $sp
+    renamable $r2 = nsw t2ADDri $r0, 3, 14 /* CC::al */, $noreg, $noreg
+    $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
+    $r7 = frame-setup tMOVr killed $sp, 14 /* CC::al */, $noreg
+    early-clobber $sp = frame-setup t2STR_PRE killed $r12, $sp, -4, 14 /* CC::al */, $noreg
+    $r12, $sp = frame-destroy t2LDR_POST $sp, 4, 14 /* CC::al */, $noreg
+    $sp = frame-destroy t2LDMIA_UPD $sp, 14 /* CC::al */, $noreg, def $r7, def $lr
+    t2AUT implicit $r12, implicit $lr, implicit $sp
+    tBX_RET 14 /* CC::al */, $noreg, implicit $r0
+
+...
+
+# CHECK-LABEL: name:            foo_pac
+# CHECK:       body:
+# CHECK-NEXT:    bb.0.entry:
+# CHECK-NEXT:      liveins: $r0, $lr, $r12
+# CHECK-NEXT:      {{^ +$}}
+# CHECK-NEXT:      frame-setup t2PAC implicit-def $r12, implicit $lr, implicit $sp
+
+---
+name:            foo_pacbti
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $r0, $lr, $r12
+
+    frame-setup t2PACBTI implicit-def $r12, implicit $lr, implicit $sp
+    renamable $r2 = nsw t2ADDri $r0, 3, 14 /* CC::al */, $noreg, $noreg
+    $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
+    $r7 = frame-setup tMOVr killed $sp, 14 /* CC::al */, $noreg
+    early-clobber $sp = frame-setup t2STR_PRE killed $r12, $sp, -4, 14 /* CC::al */, $noreg
+    $r12, $sp = frame-destroy t2LDR_POST $sp, 4, 14 /* CC::al */, $noreg
+    $sp = frame-destroy t2LDMIA_UPD $sp, 14 /* CC::al */, $noreg, def $r7, def $lr
+    t2AUT implicit $r12, implicit $lr, implicit $sp
+    tBX_RET 14 /* CC::al */, $noreg, implicit $r0
+
+...
+
+# CHECK-LABEL: name:            foo_pacbti
+# CHECK:       body:
+# CHECK-NEXT:    bb.0.entry:
+# CHECK-NEXT:      liveins: $r0, $lr, $r12
+# CHECK-NEXT:      {{^ +$}}
+# CHECK-NEXT:      frame-setup t2PACBTI implicit-def $r12, implicit $lr, implicit $sp
+
+---
+name:            foo_setjmp
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    successors: %bb.1
+    liveins: $lr
+
+    frame-setup tPUSH 14 /* CC::al */, $noreg, $r7, killed $lr, implicit-def $sp, implicit $sp
+    $r7 = frame-setup tMOVr $sp, 14 /* CC::al */, $noreg
+    $sp = frame-setup tSUBspi $sp, 40, 14 /* CC::al */, $noreg
+    renamable $r0 = tMOVr $sp, 14 /* CC::al */, $noreg
+    tBL 14 /* CC::al */, $noreg, @setjmp, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $r0, implicit-def $sp, implicit-def $r0
+    t2BTI
+    renamable $r2 = nsw t2ADDri $r0, 3, 14 /* CC::al */, $noreg, $noreg
+    tCMPi8 killed renamable $r0, 0, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    t2IT 0, 2, implicit-def $itstate
+    renamable $r0 = tMOVi8 $noreg, 0, 0 /* CC::eq */, $cpsr, implicit $itstate
+    $sp = frame-destroy tADDspi $sp, 40, 0 /* CC::eq */, $cpsr, implicit $itstate
+    frame-destroy tPOP_RET 0 /* CC::eq */, killed $cpsr, def $r7, def $pc, implicit killed $r0, implicit $sp, implicit killed $itstate
+
+  bb.1.if.then:
+    renamable $r0 = tMOVr $sp, 14 /* CC::al */, $noreg
+    renamable $r1, dead $cpsr = tMOVi8 1, 14 /* CC::al */, $noreg
+    tBL 14 /* CC::al */, $noreg, @longjmp, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $r0, implicit killed $r1, implicit-def $sp
+
+...
+
+# CHECK-LABEL: name:            foo_setjmp
+# CHECK:       body:
+# CHECK:         tBL 14 /* CC::al */, $noreg, @setjmp, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit killed $r0, implicit-def $sp, implicit-def $r0
+# CHECK-NEXT:    t2BTI
+
+---
+name:            foo_sg
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $r0
+
+    t2SG 14 /* CC::al */, $noreg
+    renamable $r0, dead $cpsr = nsw tADDi8 killed renamable $r0, 1, 14 /* CC::al */, $noreg
+    tBX_RET 14 /* CC::al */, $noreg, implicit killed $r0
+
+...
+
+# CHECK-LABEL: name:            foo_sg
+# CHECK:       body:
+# CHECK-NEXT:   bb.0.entry:
+# CHECK-NEXT:     liveins: $r0
+# CHECK-NEXT:     {{^ +$}}
+# CHECK-NEXT:     t2SG