Index: llvm/lib/CodeGen/RegAllocGreedy.cpp
===================================================================
--- llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -552,7 +552,7 @@
     LastEvicted.addEviction(PhysReg, VirtReg.reg(), Intf->reg());
 
     Matrix->unassign(*Intf);
-    assert((ExtraInfo->getCascade(Intf->reg()) < Cascade ||
+    assert((ExtraInfo->getCascade(Intf->reg()) <= Cascade ||
             VirtReg.isSpillable() < Intf->isSpillable()) &&
            "Cannot decrease cascade number, illegal eviction");
     ExtraInfo->setCascade(Intf->reg(), Cascade);
Index: llvm/test/CodeGen/AMDGPU/illegal-eviction-assert.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/illegal-eviction-assert.mir
@@ -0,0 +1,34 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: not llc -march=amdgcn -mcpu=gfx900 -start-before=greedy,0 -stop-after=virtregrewriter,1 -o - 2>%t.err %s | FileCheck %s
+# RUN: FileCheck -check-prefix=ERR %s < %t.err
+
+# ERR: error: ran out of registers during register allocation
+
+--- |
+  define void @foo() #0 {
+    ret void
+  }
+
+  attributes #0 = { "amdgpu-waves-per-eu"="8,8"  }
+
+...
+
+# CHECK: S_NOP 0, implicit-def renamable $vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27, implicit-def renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11, implicit-def renamable $vgpr28_vgpr29_vgpr30_vgpr31, implicit-def dead renamable $vgpr0_vgpr1_vgpr2_vgpr3, implicit-def dead renamable $vgpr0_vgpr1_vgpr2_vgpr3
+# CHECK: S_NOP 0, implicit killed renamable $vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27, implicit killed renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11, implicit killed renamable $vgpr28_vgpr29_vgpr30_vgpr31, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3
+# CHECK: S_ENDPGM 0
+
+---
+name:            foo
+tracksRegLiveness: true
+machineFunctionInfo:
+  scratchRSrcReg:  '$sgpr0_sgpr1_sgpr2_sgpr3'
+  frameOffsetReg:  '$sgpr33'
+  stackPtrOffsetReg: '$sgpr32'
+body:             |
+  bb.0:
+    S_NOP 0, implicit-def %0:vreg_512, implicit-def %1:vreg_256, implicit-def %2:vreg_128, implicit-def %3:vreg_128, implicit-def %4:vreg_128
+
+    S_NOP 0, implicit %0, implicit %1, implicit %2, implicit %3, implicit %4
+    S_ENDPGM 0
+
+...