[Statepoint] Use correct RegisterClass for spilling

[danilaml]

Summary

Copy propagation might have changed the register class of the register

[skatkov]

Thanks.

llvm/lib/CodeGen/FixupStatepointCallerSaved.cpp

 //===-- FixupStatepointCallerSaved.cpp - Fixup caller saved registers  ----===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
bool findRegistersToSpill() {
     return !RegsToSpill.empty();
   }
 
   // Spill all caller saved registers right before statepoint instruction.
   // Remember frame index where register is spilled.
   void spillRegisters() {
     for (Register Reg : RegsToSpill) {
       int FI = CacheFI.getFrameIndex(Reg, EHPad);
-      const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
 
       NumSpilledRegisters++;
       RegToSlotIdx[Reg] = FI;
 
       LLVM_DEBUG(dbgs() << "Spilling " << printReg(Reg, &TRI) << " to FI " << FI
                         << "\n");
 
       // Perform trivial copy propagation
       bool IsKill = true;
       MachineBasicBlock::iterator InsertBefore(MI);
       Reg = performCopyPropagation(Reg, InsertBefore, IsKill, TII, TRI);
+      const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
 
       LLVM_DEBUG(dbgs() << "Insert spill before " << *InsertBefore);
       TII.storeRegToStackSlot(*MI.getParent(), InsertBefore, Reg, IsKill, FI,
                               RC, &TRI, Register());
     }
   }
 
   void insertReloadBefore(unsigned Reg, MachineBasicBlock::iterator It,

llvm/test/CodeGen/AArch64/aarch64-fixup-statepoint-regs-crash.ll

-; XFAIL: *
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --extra_scrub --version 3
 ; REQUIRES: asserts
-; RUN: llc -verify-machineinstrs -max-registers-for-gc-values=256 -mtriple=aarch64-none-linux-gnu < %s
+; RUN: llc -verify-machineinstrs -max-registers-for-gc-values=256 -mtriple=aarch64-none-linux-gnu < %s | FileCheck %s
 
+; Verify that FixupStatepointCallerSaved pass uses correct intruction for spilling a register after copyprop
 define dso_local ptr addrspace(1) @foo(ptr addrspace(1) %arg) gc "statepoint-example" personality ptr null {
+; CHECK-LABEL: foo:
+; CHECK:       .Lfunc_begin0:
+; CHECK-NEXT:    .cfi_startproc
+; CHECK-NEXT:  // %bb.0:
+; CHECK-NEXT:    sub sp, sp, #48
+; CHECK-NEXT:    stp x30, x19, [sp, #32] // 16-byte Folded Spill
+; CHECK-NEXT:    .cfi_def_cfa_offset 48
+; CHECK-NEXT:    .cfi_offset w19, -8
+; CHECK-NEXT:    .cfi_offset w30, -16
+; CHECK-NEXT:    ldr q0, [x0]
+; CHECK-NEXT:    str d0, [sp, #8] // 8-byte Folded Spill
+; CHECK-NEXT:    str q0, [sp, #16]
+; CHECK-NEXT:    bl baz // 8-byte Folded Reload
+; CHECK-NEXT:  .Ltmp0:
+; CHECK-NEXT:    ldp x19, x0, [sp, #8] // 8-byte Folded Reload
+; CHECK-NEXT:    ldp x30, x19, [sp, #32] // 16-byte Folded Reload
+; CHECK-NEXT:    add sp, sp, #48
+; CHECK-NEXT:    ret
   %load = load <2 x ptr addrspace(1)>, ptr addrspace(1) %arg, align 8
   %extractelement = extractelement <2 x ptr addrspace(1)> %load, i64 0
   %call = call token (i64, i32, ptr, i32, i32, ...) @llvm.experimental.gc.statepoint.p0(i64 2882400000, i32 0, ptr nonnull elementtype(void ()) @baz, i32 0, i32 0, i32 0, i32 0) [ "deopt"(ptr addrspace(1) %extractelement), "gc-live"(<2 x ptr addrspace(1)> %load) ]
   %relocate = call coldcc <2 x ptr addrspace(1)> @llvm.experimental.gc.relocate.v2p1(token %call, i32 0, i32 0)
   %extractelement2 = extractelement <2 x ptr addrspace(1)> %relocate, i64 0
   ret ptr addrspace(1) %extractelement2
 }
 
 declare void @baz()
 declare token @llvm.experimental.gc.statepoint.p0(i64, i32, ptr, i32, i32, ...)
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(none)
 declare <2 x ptr addrspace(1)> @llvm.experimental.gc.relocate.v2p1(token, i32, i32) #0
 
 attributes #0 = { nocallback nofree nosync nounwind willreturn memory(none) }