commit 163c77b2e0831853b59cdd24ece9637f8a19cc79
Author: Serguei Katkov <serguei.katkov@azul.com>
Date:   Wed Jun 8 19:14:20 2022 +0700

    [AARCH64 folding] Do not fold any copy with NZCV
    
    There is no instruction to fold NZCV, so, just do not do it.
    
    Without the fix the added test case crashes with an assert
    "Mismatched register size in non subreg COPY"
    
    Reviewed By: danilaml
    Subscribers: llvm-commits
    Differential Revision: https://reviews.llvm.org/D127294

diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 77135de1d3f3..05fd190a6e54 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -4437,6 +4437,9 @@ MachineInstr *AArch64InstrInfo::foldMemoryOperandImpl(
       MF.getRegInfo().constrainRegClass(SrcReg, &AArch64::GPR64RegClass);
       return nullptr;
     }
+    // Nothing can folded with copy from/to NZCV.
+    if (SrcReg == AArch64::NZCV || DstReg == AArch64::NZCV)
+      return nullptr;
   }
 
   // Handle the case where a copy is being spilled or filled but the source
diff --git a/llvm/test/CodeGen/AArch64/spill-fold.mir b/llvm/test/CodeGen/AArch64/spill-fold.mir
index 624fcc449b6c..02d409d04da7 100644
--- a/llvm/test/CodeGen/AArch64/spill-fold.mir
+++ b/llvm/test/CodeGen/AArch64/spill-fold.mir
@@ -5,6 +5,7 @@
   define i64 @test_subreg_spill_fold3() { ret i64 0 }
   define i64 @test_subreg_fill_fold() { ret i64 0 }
   define double @test_subreg_fill_fold2() { ret double 0.0 }
+  define i64 @test_nzcv_spill_fold() { ret i64 0 }
 ...
 ---
 # CHECK-LABEL: name: test_subreg_spill_fold
@@ -80,3 +81,18 @@ body:             |
     $d0 = COPY %1
     RET_ReallyLR implicit $d0
 ...
+---
+# CHECK-LABEL: name: test_nzcv_spill_fold
+# Ensure that nzcv COPY cannot be folded.
+name:            test_nzcv_spill_fold
+registers:
+  - { id: 0, class: gpr64 }
+body:             |
+  bb.0:
+    ; CHECK: %1:gpr64 = COPY $nzcv
+    ; CHECK: STRXui %1, %stack.0, 0 :: (store (s64) into %stack.0)
+    %0 = COPY $nzcv
+    INLINEASM &nop, 1, 12, implicit-def dead $x0, 12, implicit-def dead $x1, 12, implicit-def dead $x2, 12, implicit-def dead $x3, 12, implicit-def dead $x4, 12, implicit-def dead $x5, 12, implicit-def dead $x6, 12, implicit-def dead $x7, 12, implicit-def dead $x8, 12, implicit-def dead $x9, 12, implicit-def dead $x10, 12, implicit-def dead $x11, 12, implicit-def dead $x12, 12, implicit-def dead $x13, 12, implicit-def dead $x14, 12, implicit-def dead $x15, 12, implicit-def dead $x16, 12, implicit-def dead $x17, 12, implicit-def dead $x18, 12, implicit-def dead $x19, 12, implicit-def dead $x20, 12, implicit-def dead $x21, 12, implicit-def dead $x22, 12, implicit-def dead $x23, 12, implicit-def dead $x24, 12, implicit-def dead $x25, 12, implicit-def dead $x26, 12, implicit-def dead $x27, 12, implicit-def dead $x28, 12, implicit-def dead $fp, 12, implicit-def dead $lr, 12, implicit-def $sp
+    $x0 = COPY %0
+    RET_ReallyLR implicit $x0
+...