[AMDGPU] Reuse register during frame index elimination

[kerbowa]

Summary

If there were no free VGPRs we would need two emergency spill slots for register
scavenging during PEI/frame index elimination. Reuse 'ResultReg' for scale
calculation so that only one spill is needed.

[arsenm]

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

1167–1168

Typo Resue

llvm/test/CodeGen/AMDGPU/pei-scavenge-vgpr-spill.mir

3

Add other subtarget run lines to catch the different add handling?

24

I assume these live ins are just to force all registers to be live? I think this will break when things are finally inverted to scavenge from the end of the block. I think there should also be an implicit use on the S_ENDPGM (I think you can use the all VGPR reg mask to shorten it)

38

We ended up with an add of 0 which doesn't seem ideal

[craig.topper]

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

1167–1168

Same typo exists in the review title too

[kerbowa]

Address review comments.

[kerbowa]

llvm/test/CodeGen/AMDGPU/pei-scavenge-vgpr-spill.mir

24

Is csr_amdgpu_allvgprs the mask you are referring to?

38

I don't think I see an add of 0.

[kerbowa]

Rebase tests.

[arsenm]

llvm/test/CodeGen/AMDGPU/pei-scavenge-vgpr-spill.mir

24

Yes, though the CSR part is misleading

38

Oh right, I got confused by the clamp immediate

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

default: {
         int64_t Offset = FrameInfo.getObjectOffset(Index);
         if (Offset == 0) {
           // XXX - This never happens because of emergency scavenging slot at 0?
           BuildMI(*MBB, MI, DL, TII->get(AMDGPU::V_LSHRREV_B32_e64), ResultReg)
             .addImm(ST.getWavefrontSizeLog2())
             .addReg(DiffReg);
         } else {
           if (auto MIB = TII->getAddNoCarry(*MBB, MI, DL, ResultReg, *RS)) {
-            Register ScaledReg =
-              RS->scavengeRegister(&AMDGPU::VGPR_32RegClass, MIB, 0);
+            // Reuse ResultReg in intermediate step.
+            Register ScaledReg = ResultReg;
 
             BuildMI(*MBB, *MIB, DL, TII->get(AMDGPU::V_LSHRREV_B32_e64),
                     ScaledReg)
               .addImm(ST.getWavefrontSizeLog2())
               .addReg(DiffReg, RegState::Kill);
 
             const bool IsVOP2 = MIB->getOpcode() == AMDGPU::V_ADD_U32_e32;
 

llvm/test/CodeGen/AMDGPU/frame-index-elimination.ll

define void @func_mov_fi_i32() #0 {
   ret void
 }
 
 ; Offset due to different objects
 ; GCN-LABEL: {{^}}func_mov_fi_i32_offset:
 ; GCN: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
 
 ; CI: s_sub_u32 [[SUB0:s[0-9]+|vcc_lo|vcc_hi]], s32, s33
+; CI-NEXT: v_lshr_b32_e64 v0, [[SUB0]], 6
+; CI-NEXT: s_mov_b32 m0, -1
 ; CI-NEXT: s_sub_u32 [[SUB1:s[0-9]+|vcc_lo|vcc_hi]], s32, s33
-; CI-DAG: v_lshr_b32_e64 v0, [[SUB0]], 6
-; CI-DAG: v_lshr_b32_e64 [[SCALED:v[0-9]+]], [[SUB1]], 6
-; CI-NOT: v_mov
-; CI: ds_write_b32 v0, v0
+; CI-NEXT: ds_write_b32 v0, v0
+; CI-NEXT: v_lshr_b32_e64 [[SCALED:v[0-9]+]], [[SUB1]], 6
 ; CI-NEXT: v_add_i32_e64 v0, s{{\[[0-9]+:[0-9]+\]}}, 4, [[SCALED]]
 ; CI-NEXT: ds_write_b32 v0, v0
 
 ; GFX9: s_sub_u32 [[SUB0:s[0-9]+|vcc_lo|vcc_hi]], s32, s33
-; GFX9-NEXT: s_sub_u32 [[SUB1:s[0-9]+|vcc_lo|vcc_hi]], s32, s33
 ; GFX9-NEXT: v_lshrrev_b32_e64 v0, 6, [[SUB0]]
+; GFX9-NEXT: s_sub_u32 [[SUB1:s[0-9]+|vcc_lo|vcc_hi]], s32, s33
+; GFX9-NEXT: ds_write_b32 v0, v0
 ; GFX9-NEXT: v_lshrrev_b32_e64 [[SCALED:v[0-9]+]], 6, [[SUB1]]
-; GFX9-DAG: ds_write_b32 v0, v0
 ; GFX9-NEXT: v_add_u32_e32 v0, 4, [[SCALED]]
 ; GFX9-NEXT: ds_write_b32 v0, v0
 define void @func_mov_fi_i32_offset() #0 {
   %alloca0 = alloca i32, addrspace(5)
   %alloca1 = alloca i32, addrspace(5)
   store volatile i32 addrspace(5)* %alloca0, i32 addrspace(5)* addrspace(3)* undef
   store volatile i32 addrspace(5)* %alloca1, i32 addrspace(5)* addrspace(3)* undef
   ret void

llvm/test/CodeGen/AMDGPU/pei-scavenge-sgpr-carry-out.mir

bb.0:
     ; CHECK-LABEL: name: scavenge_sgpr_pei_one_sgpr_64
     ; CHECK: liveins: $vgpr1
     ; CHECK: $sgpr27 = frame-setup COPY $sgpr33
     ; CHECK: $sgpr4 = frame-setup S_ADD_U32 $sgpr32, 524224, implicit-def $scc
     ; CHECK: $sgpr33 = frame-setup S_AND_B32 killed $sgpr4, 4294443008, implicit-def $scc
     ; CHECK: $sgpr32 = frame-setup S_ADD_U32 $sgpr32, 1572864, implicit-def $scc
     ; CHECK: S_NOP 0, implicit-def $sgpr4, implicit-def $sgpr5, implicit-def $sgpr6, implicit-def $sgpr7, implicit-def $sgpr8, implicit-def $sgpr9, implicit-def $sgpr10, implicit-def $sgpr11, implicit-def $sgpr12, implicit-def $sgpr13, implicit-def $sgpr14, implicit-def $sgpr15, implicit-def $sgpr16, implicit-def $sgpr17, implicit-def $sgpr18, implicit-def $sgpr19, implicit-def $sgpr20, implicit-def $sgpr21, implicit-def $sgpr22, implicit-def $sgpr23, implicit-def $sgpr24, implicit-def $sgpr25, implicit-def $sgpr26, implicit-def $sgpr17, implicit-def $sgpr30, implicit-def $sgpr31, implicit-def $vcc
     ; CHECK: $sgpr28 = S_SUB_U32 $sgpr33, $sgpr34, implicit-def $scc
-    ; CHECK: $vgpr3 = V_LSHRREV_B32_e64 6, killed $sgpr28, implicit $exec
+    ; CHECK: $vgpr2 = V_LSHRREV_B32_e64 6, killed $sgpr28, implicit $exec
     ; CHECK: $sgpr28 = S_MOV_B32 8192
-    ; CHECK: $vgpr2, dead $sgpr28_sgpr29 = V_ADD_I32_e64 killed $sgpr28, killed $vgpr3, 0, implicit $exec
+    ; CHECK: $vgpr2, dead $sgpr28_sgpr29 = V_ADD_I32_e64 killed $sgpr28, killed $vgpr2, 0, implicit $exec
     ; CHECK: $vgpr0 = V_OR_B32_e32 killed $vgpr2, $vgpr1, implicit $exec, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr17, implicit $sgpr31
     ; CHECK: $sgpr32 = frame-destroy S_SUB_U32 $sgpr32, 1572864, implicit-def $scc
     ; CHECK: $sgpr33 = frame-setup COPY $sgpr27
     ; CHECK: S_ENDPGM 0, implicit $vcc
     S_NOP 0, implicit-def $sgpr4, implicit-def $sgpr5, implicit-def $sgpr6, implicit-def $sgpr7, implicit-def $sgpr8, implicit-def $sgpr9, implicit-def $sgpr10, implicit-def $sgpr11, implicit-def $sgpr12, implicit-def $sgpr13, implicit-def $sgpr14, implicit-def $sgpr15, implicit-def $sgpr16, implicit-def $sgpr17, implicit-def $sgpr18, implicit-def $sgpr19, implicit-def $sgpr20, implicit-def $sgpr21, implicit-def $sgpr22, implicit-def $sgpr23, implicit-def $sgpr24, implicit-def $sgpr25, implicit-def $sgpr26, implicit-def $sgpr17, implicit-def $sgpr30, implicit-def $sgpr31, implicit-def $vcc
     $vgpr0 = V_OR_B32_e32 %stack.1, $vgpr1, implicit $exec, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr17, implicit $sgpr31
     S_ENDPGM 0, implicit $vcc
 ...
bb.0:
     ; CHECK-LABEL: name: scavenge_sgpr_pei_prefer_vcc
     ; CHECK: liveins: $vgpr1
     ; CHECK: $sgpr27 = frame-setup COPY $sgpr33
     ; CHECK: $sgpr4 = frame-setup S_ADD_U32 $sgpr32, 524224, implicit-def $scc
     ; CHECK: $sgpr33 = frame-setup S_AND_B32 killed $sgpr4, 4294443008, implicit-def $scc
     ; CHECK: $sgpr32 = frame-setup S_ADD_U32 $sgpr32, 1572864, implicit-def $scc
     ; CHECK: S_NOP 0, implicit-def $sgpr4, implicit-def $sgpr5, implicit-def $sgpr6, implicit-def $sgpr7, implicit-def $sgpr8, implicit-def $sgpr9, implicit-def $sgpr10, implicit-def $sgpr11, implicit-def $sgpr12, implicit-def $sgpr13, implicit-def $sgpr14, implicit-def $sgpr15, implicit-def $sgpr16, implicit-def $sgpr17, implicit-def $sgpr18, implicit-def $sgpr19, implicit-def $sgpr20, implicit-def $sgpr21, implicit-def $sgpr22, implicit-def $sgpr23, implicit-def $sgpr24, implicit-def $sgpr25, implicit-def $sgpr26, implicit-def $sgpr17, implicit-def $sgpr30, implicit-def $sgpr31
     ; CHECK: $vcc_hi = S_SUB_U32 $sgpr33, $sgpr34, implicit-def $scc
-    ; CHECK: $vgpr3 = V_LSHRREV_B32_e64 6, killed $vcc_hi, implicit $exec
+    ; CHECK: $vgpr2 = V_LSHRREV_B32_e64 6, killed $vcc_hi, implicit $exec
     ; CHECK: $vcc_lo = S_MOV_B32 8192
-    ; CHECK: $vgpr2, dead $vcc = V_ADD_I32_e64 killed $vcc_lo, killed $vgpr3, 0, implicit $exec
+    ; CHECK: $vgpr2, dead $vcc = V_ADD_I32_e64 killed $vcc_lo, killed $vgpr2, 0, implicit $exec
     ; CHECK: $vgpr0 = V_OR_B32_e32 killed $vgpr2, $vgpr1, implicit $exec, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr17, implicit $sgpr31
     ; CHECK: $sgpr32 = frame-destroy S_SUB_U32 $sgpr32, 1572864, implicit-def $scc
     ; CHECK: $sgpr33 = frame-setup COPY $sgpr27
     ; CHECK: S_ENDPGM 0
     S_NOP 0, implicit-def $sgpr4, implicit-def $sgpr5, implicit-def $sgpr6, implicit-def $sgpr7, implicit-def $sgpr8, implicit-def $sgpr9, implicit-def $sgpr10, implicit-def $sgpr11, implicit-def $sgpr12, implicit-def $sgpr13, implicit-def $sgpr14, implicit-def $sgpr15, implicit-def $sgpr16, implicit-def $sgpr17, implicit-def $sgpr18, implicit-def $sgpr19, implicit-def $sgpr20, implicit-def $sgpr21, implicit-def $sgpr22, implicit-def $sgpr23, implicit-def $sgpr24, implicit-def $sgpr25, implicit-def $sgpr26, implicit-def $sgpr17, implicit-def $sgpr30, implicit-def $sgpr31
     $vgpr0 = V_OR_B32_e32 %stack.1, $vgpr1, implicit $exec, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr17, implicit $sgpr31
     S_ENDPGM 0
 ...

llvm/test/CodeGen/AMDGPU/pei-scavenge-sgpr-gfx9.mir

bb.0:
     ; CHECK-LABEL: name: scavenge_sgpr_pei_no_sgprs
     ; CHECK: liveins: $vgpr1
     ; CHECK: $sgpr27 = frame-setup COPY $sgpr33
     ; CHECK: $sgpr4 = frame-setup S_ADD_U32 $sgpr32, 524224, implicit-def $scc
     ; CHECK: $sgpr33 = frame-setup S_AND_B32 killed $sgpr4, 4294443008, implicit-def $scc
     ; CHECK: $sgpr32 = frame-setup S_ADD_U32 $sgpr32, 1572864, implicit-def $scc
     ; CHECK: S_NOP 0, implicit-def $sgpr4, implicit-def $sgpr5, implicit-def $sgpr6, implicit-def $sgpr7, implicit-def $sgpr8, implicit-def $sgpr9, implicit-def $sgpr10, implicit-def $sgpr11, implicit-def $sgpr12, implicit-def $sgpr13, implicit-def $sgpr14, implicit-def $sgpr15, implicit-def $sgpr16, implicit-def $sgpr17, implicit-def $sgpr18, implicit-def $sgpr19, implicit-def $sgpr20, implicit-def $sgpr21, implicit-def $sgpr22, implicit-def $sgpr23, implicit-def $sgpr24, implicit-def $sgpr25, implicit-def $sgpr26, implicit-def $sgpr17, implicit-def $sgpr28, implicit-def $sgpr29, implicit-def $sgpr30, implicit-def $sgpr31, implicit-def $vcc
     ; CHECK: $sgpr33 = S_SUB_U32 $sgpr33, $sgpr34, implicit-def $scc
-    ; CHECK: $vgpr3 = V_LSHRREV_B32_e64 6, killed $sgpr33, implicit $exec
-    ; CHECK: $vgpr2 = V_ADD_U32_e32 8192, killed $vgpr3, implicit $exec
+    ; CHECK: $vgpr2 = V_LSHRREV_B32_e64 6, killed $sgpr33, implicit $exec
+    ; CHECK: $vgpr2 = V_ADD_U32_e32 8192, killed $vgpr2, implicit $exec
     ; CHECK: $sgpr33 = S_ADD_U32 $sgpr33, $sgpr34, implicit-def $scc
     ; CHECK: $vgpr0 = V_OR_B32_e32 killed $vgpr2, $vgpr1, implicit $exec, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr17, implicit $sgpr28, implicit $sgpr29, implicit $sgpr30, implicit $sgpr31
     ; CHECK: $sgpr32 = frame-destroy S_SUB_U32 $sgpr32, 1572864, implicit-def $scc
     ; CHECK: $sgpr33 = frame-setup COPY $sgpr27
     ; CHECK: S_ENDPGM 0, implicit $vcc
     S_NOP 0, implicit-def $sgpr4, implicit-def $sgpr5, implicit-def $sgpr6, implicit-def $sgpr7, implicit-def $sgpr8, implicit-def $sgpr9, implicit-def $sgpr10, implicit-def $sgpr11, implicit-def $sgpr12, implicit-def $sgpr13, implicit-def $sgpr14, implicit-def $sgpr15, implicit-def $sgpr16, implicit-def $sgpr17, implicit-def $sgpr18, implicit-def $sgpr19, implicit-def $sgpr20, implicit-def $sgpr21, implicit-def $sgpr22, implicit-def $sgpr23, implicit-def $sgpr24, implicit-def $sgpr25, implicit-def $sgpr26, implicit-def $sgpr17, implicit-def $sgpr28, implicit-def $sgpr29, implicit-def $sgpr30, implicit-def $sgpr31, implicit-def $vcc
     $vgpr0 = V_OR_B32_e32 %stack.1, $vgpr1, implicit $exec, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr17, implicit $sgpr28, implicit $sgpr29, implicit $sgpr30, implicit $sgpr31
     S_ENDPGM 0, implicit $vcc
 ...

llvm/test/CodeGen/AMDGPU/pei-scavenge-vgpr-spill.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=fiji -verify-machineinstrs -run-pass=prologepilog %s -o - | FileCheck -check-prefix=GFX8 %s
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -verify-machineinstrs -run-pass=prologepilog %s -o - | FileCheck -check-prefix=GFX9 %s
+
+# Test case where spilling a VGPR to an emergency slot is needed during frame index elimination.
+
+---
+name: pei_scavenge_vgpr_spill
+tracksRegLiveness: true
+
+stack:
+  - { id: 0, type: default, offset: 0, size: 4, alignment: 8192 }
+  - { id: 1, type: default, offset: 0, size: 4, alignment: 8192 }
+
+machineFunctionInfo:
+  isEntryFunction: false
+  scratchRSrcReg:  $sgpr0_sgpr1_sgpr2_sgpr3
+  scratchWaveOffsetReg: $sgpr34
+  frameOffsetReg:  $sgpr33
+  stackPtrOffsetReg:  $sgpr32
+
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15, $vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27_vgpr28_vgpr29_vgpr30_vgpr31, $vgpr32_vgpr33_vgpr34_vgpr35_vgpr36_vgpr37_vgpr38_vgpr39_vgpr40_vgpr41_vgpr42_vgpr43_vgpr44_vgpr45_vgpr46_vgpr47, $vgpr48_vgpr49_vgpr50_vgpr51_vgpr52_vgpr53_vgpr54_vgpr55_vgpr56_vgpr57_vgpr58_vgpr59_vgpr60_vgpr61_vgpr62_vgpr63, $vgpr64_vgpr65_vgpr66_vgpr67_vgpr68_vgpr69_vgpr70_vgpr71_vgpr72_vgpr73_vgpr74_vgpr75_vgpr76_vgpr77_vgpr78_vgpr79, $vgpr80_vgpr81_vgpr82_vgpr83_vgpr84_vgpr85_vgpr86_vgpr87_vgpr88_vgpr89_vgpr90_vgpr91_vgpr92_vgpr93_vgpr94_vgpr95, $vgpr96_vgpr97_vgpr98_vgpr99_vgpr100_vgpr101_vgpr102_vgpr103_vgpr104_vgpr105_vgpr106_vgpr107_vgpr108_vgpr109_vgpr110_vgpr111, $vgpr112_vgpr113_vgpr114_vgpr115_vgpr116_vgpr117_vgpr118_vgpr119_vgpr120_vgpr121_vgpr122_vgpr123_vgpr124_vgpr125_vgpr126_vgpr127, $vgpr128_vgpr129_vgpr130_vgpr131_vgpr132_vgpr133_vgpr134_vgpr135_vgpr136_vgpr137_vgpr138_vgpr139_vgpr140_vgpr141_vgpr142_vgpr143, $vgpr144_vgpr145_vgpr146_vgpr147_vgpr148_vgpr149_vgpr150_vgpr151_vgpr152_vgpr153_vgpr154_vgpr155_vgpr156_vgpr157_vgpr158_vgpr159, $vgpr160_vgpr161_vgpr162_vgpr163_vgpr164_vgpr165_vgpr166_vgpr167_vgpr168_vgpr169_vgpr170_vgpr171_vgpr172_vgpr173_vgpr174_vgpr175, $vgpr176_vgpr177_vgpr178_vgpr179_vgpr180_vgpr181_vgpr182_vgpr183_vgpr184_vgpr185_vgpr186_vgpr187_vgpr188_vgpr189_vgpr190_vgpr191, $vgpr192_vgpr193_vgpr194_vgpr195_vgpr196_vgpr197_vgpr198_vgpr199_vgpr200_vgpr201_vgpr202_vgpr203_vgpr204_vgpr205_vgpr206_vgpr207, $vgpr208_vgpr209_vgpr210_vgpr211_vgpr212_vgpr213_vgpr214_vgpr215_vgpr216_vgpr217_vgpr218_vgpr219_vgpr220_vgpr221_vgpr222_vgpr223, $vgpr224_vgpr225_vgpr226_vgpr227_vgpr228_vgpr229_vgpr230_vgpr231_vgpr232_vgpr233_vgpr234_vgpr235_vgpr236_vgpr237_vgpr238_vgpr239, $vgpr240_vgpr241_vgpr242_vgpr243_vgpr244_vgpr245_vgpr246_vgpr247, $vgpr248_vgpr249_vgpr250_vgpr251, $vgpr252_vgpr253_vgpr254_vgpr255
+
+    ; GFX8-LABEL: name: pei_scavenge_vgpr_spill
+    ; GFX8: liveins: $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15, $vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27_vgpr28_vgpr29_vgpr30_vgpr31, $vgpr32_vgpr33_vgpr34_vgpr35_vgpr36_vgpr37_vgpr38_vgpr39_vgpr40_vgpr41_vgpr42_vgpr43_vgpr44_vgpr45_vgpr46_vgpr47, $vgpr48_vgpr49_vgpr50_vgpr51_vgpr52_vgpr53_vgpr54_vgpr55_vgpr56_vgpr57_vgpr58_vgpr59_vgpr60_vgpr61_vgpr62_vgpr63, $vgpr64_vgpr65_vgpr66_vgpr67_vgpr68_vgpr69_vgpr70_vgpr71_vgpr72_vgpr73_vgpr74_vgpr75_vgpr76_vgpr77_vgpr78_vgpr79, $vgpr80_vgpr81_vgpr82_vgpr83_vgpr84_vgpr85_vgpr86_vgpr87_vgpr88_vgpr89_vgpr90_vgpr91_vgpr92_vgpr93_vgpr94_vgpr95, $vgpr96_vgpr97_vgpr98_vgpr99_vgpr100_vgpr101_vgpr102_vgpr103_vgpr104_vgpr105_vgpr106_vgpr107_vgpr108_vgpr109_vgpr110_vgpr111, $vgpr112_vgpr113_vgpr114_vgpr115_vgpr116_vgpr117_vgpr118_vgpr119_vgpr120_vgpr121_vgpr122_vgpr123_vgpr124_vgpr125_vgpr126_vgpr127, $vgpr128_vgpr129_vgpr130_vgpr131_vgpr132_vgpr133_vgpr134_vgpr135_vgpr136_vgpr137_vgpr138_vgpr139_vgpr140_vgpr141_vgpr142_vgpr143, $vgpr144_vgpr145_vgpr146_vgpr147_vgpr148_vgpr149_vgpr150_vgpr151_vgpr152_vgpr153_vgpr154_vgpr155_vgpr156_vgpr157_vgpr158_vgpr159, $vgpr160_vgpr161_vgpr162_vgpr163_vgpr164_vgpr165_vgpr166_vgpr167_vgpr168_vgpr169_vgpr170_vgpr171_vgpr172_vgpr173_vgpr174_vgpr175, $vgpr176_vgpr177_vgpr178_vgpr179_vgpr180_vgpr181_vgpr182_vgpr183_vgpr184_vgpr185_vgpr186_vgpr187_vgpr188_vgpr189_vgpr190_vgpr191, $vgpr192_vgpr193_vgpr194_vgpr195_vgpr196_vgpr197_vgpr198_vgpr199_vgpr200_vgpr201_vgpr202_vgpr203_vgpr204_vgpr205_vgpr206_vgpr207, $vgpr208_vgpr209_vgpr210_vgpr211_vgpr212_vgpr213_vgpr214_vgpr215_vgpr216_vgpr217_vgpr218_vgpr219_vgpr220_vgpr221_vgpr222_vgpr223, $vgpr224_vgpr225_vgpr226_vgpr227_vgpr228_vgpr229_vgpr230_vgpr231_vgpr232_vgpr233_vgpr234_vgpr235_vgpr236_vgpr237_vgpr238_vgpr239, $vgpr240_vgpr241_vgpr242_vgpr243_vgpr244_vgpr245_vgpr246_vgpr247, $vgpr248_vgpr249_vgpr250_vgpr251, $vgpr252_vgpr253_vgpr254_vgpr255, $vgpr2
+    ; GFX8: $vgpr2 = V_WRITELANE_B32_vi $sgpr33, 0, undef $vgpr2
+    ; GFX8: $sgpr4 = frame-setup S_ADD_U32 $sgpr32, 524224, implicit-def $scc
+    ; GFX8: $sgpr33 = frame-setup S_AND_B32 killed $sgpr4, 4294443008, implicit-def $scc
+    ; GFX8: $sgpr32 = frame-setup S_ADD_U32 $sgpr32, 1572864, implicit-def $scc
+    ; GFX8: $sgpr4 = S_ADD_U32 $sgpr33, 524544, implicit-def $scc
+    ; GFX8: BUFFER_STORE_DWORD_OFFSET killed $vgpr3, $sgpr0_sgpr1_sgpr2_sgpr3, killed $sgpr4, 0, 0, 0, 0, 0, 0, implicit $exec :: (store 4 into %stack.3, addrspace 5)
+    ; GFX8: $vcc_hi = S_SUB_U32 $sgpr33, $sgpr34, implicit-def $scc
+    ; GFX8: $vgpr3 = V_LSHRREV_B32_e64 6, killed $vcc_hi, implicit $exec
+    ; GFX8: $vcc_lo = S_MOV_B32 8192
+    ; GFX8: $vgpr3, dead $vcc = V_ADD_I32_e64 killed $vcc_lo, killed $vgpr3, 0, implicit $exec
+    ; GFX8: $vgpr0 = V_OR_B32_e32 killed $vgpr3, $vgpr1, implicit $exec
+    ; GFX8: $sgpr32 = frame-destroy S_SUB_U32 $sgpr32, 1572864, implicit-def $scc
+    ; GFX8: $sgpr33 = V_READLANE_B32_vi $vgpr2, 0
+    ; GFX8: $sgpr4 = S_ADD_U32 $sgpr33, 524544, implicit-def $scc
+    ; GFX8: $vgpr3 = BUFFER_LOAD_DWORD_OFFSET $sgpr0_sgpr1_sgpr2_sgpr3, killed $sgpr4, 0, 0, 0, 0, 0, 0, implicit $exec :: (load 4 from %stack.3, addrspace 5)
+    ; GFX8: S_ENDPGM 0, csr_amdgpu_allvgprs
+    ; GFX9-LABEL: name: pei_scavenge_vgpr_spill
+    ; GFX9: liveins: $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15, $vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27_vgpr28_vgpr29_vgpr30_vgpr31, $vgpr32_vgpr33_vgpr34_vgpr35_vgpr36_vgpr37_vgpr38_vgpr39_vgpr40_vgpr41_vgpr42_vgpr43_vgpr44_vgpr45_vgpr46_vgpr47, $vgpr48_vgpr49_vgpr50_vgpr51_vgpr52_vgpr53_vgpr54_vgpr55_vgpr56_vgpr57_vgpr58_vgpr59_vgpr60_vgpr61_vgpr62_vgpr63, $vgpr64_vgpr65_vgpr66_vgpr67_vgpr68_vgpr69_vgpr70_vgpr71_vgpr72_vgpr73_vgpr74_vgpr75_vgpr76_vgpr77_vgpr78_vgpr79, $vgpr80_vgpr81_vgpr82_vgpr83_vgpr84_vgpr85_vgpr86_vgpr87_vgpr88_vgpr89_vgpr90_vgpr91_vgpr92_vgpr93_vgpr94_vgpr95, $vgpr96_vgpr97_vgpr98_vgpr99_vgpr100_vgpr101_vgpr102_vgpr103_vgpr104_vgpr105_vgpr106_vgpr107_vgpr108_vgpr109_vgpr110_vgpr111, $vgpr112_vgpr113_vgpr114_vgpr115_vgpr116_vgpr117_vgpr118_vgpr119_vgpr120_vgpr121_vgpr122_vgpr123_vgpr124_vgpr125_vgpr126_vgpr127, $vgpr128_vgpr129_vgpr130_vgpr131_vgpr132_vgpr133_vgpr134_vgpr135_vgpr136_vgpr137_vgpr138_vgpr139_vgpr140_vgpr141_vgpr142_vgpr143, $vgpr144_vgpr145_vgpr146_vgpr147_vgpr148_vgpr149_vgpr150_vgpr151_vgpr152_vgpr153_vgpr154_vgpr155_vgpr156_vgpr157_vgpr158_vgpr159, $vgpr160_vgpr161_vgpr162_vgpr163_vgpr164_vgpr165_vgpr166_vgpr167_vgpr168_vgpr169_vgpr170_vgpr171_vgpr172_vgpr173_vgpr174_vgpr175, $vgpr176_vgpr177_vgpr178_vgpr179_vgpr180_vgpr181_vgpr182_vgpr183_vgpr184_vgpr185_vgpr186_vgpr187_vgpr188_vgpr189_vgpr190_vgpr191, $vgpr192_vgpr193_vgpr194_vgpr195_vgpr196_vgpr197_vgpr198_vgpr199_vgpr200_vgpr201_vgpr202_vgpr203_vgpr204_vgpr205_vgpr206_vgpr207, $vgpr208_vgpr209_vgpr210_vgpr211_vgpr212_vgpr213_vgpr214_vgpr215_vgpr216_vgpr217_vgpr218_vgpr219_vgpr220_vgpr221_vgpr222_vgpr223, $vgpr224_vgpr225_vgpr226_vgpr227_vgpr228_vgpr229_vgpr230_vgpr231_vgpr232_vgpr233_vgpr234_vgpr235_vgpr236_vgpr237_vgpr238_vgpr239, $vgpr240_vgpr241_vgpr242_vgpr243_vgpr244_vgpr245_vgpr246_vgpr247, $vgpr248_vgpr249_vgpr250_vgpr251, $vgpr252_vgpr253_vgpr254_vgpr255, $vgpr2
+    ; GFX9: $vgpr2 = V_WRITELANE_B32_vi $sgpr33, 0, undef $vgpr2
+    ; GFX9: $sgpr4 = frame-setup S_ADD_U32 $sgpr32, 524224, implicit-def $scc
+    ; GFX9: $sgpr33 = frame-setup S_AND_B32 killed $sgpr4, 4294443008, implicit-def $scc
+    ; GFX9: $sgpr32 = frame-setup S_ADD_U32 $sgpr32, 1572864, implicit-def $scc
+    ; GFX9: $sgpr4 = S_ADD_U32 $sgpr33, 524544, implicit-def $scc
+    ; GFX9: BUFFER_STORE_DWORD_OFFSET killed $vgpr3, $sgpr0_sgpr1_sgpr2_sgpr3, killed $sgpr4, 0, 0, 0, 0, 0, 0, implicit $exec :: (store 4 into %stack.3, addrspace 5)
+    ; GFX9: $vcc_hi = S_SUB_U32 $sgpr33, $sgpr34, implicit-def $scc
+    ; GFX9: $vgpr3 = V_LSHRREV_B32_e64 6, killed $vcc_hi, implicit $exec
+    ; GFX9: $vgpr3 = V_ADD_U32_e32 8192, killed $vgpr3, implicit $exec
+    ; GFX9: $vgpr0 = V_OR_B32_e32 killed $vgpr3, $vgpr1, implicit $exec
+    ; GFX9: $sgpr32 = frame-destroy S_SUB_U32 $sgpr32, 1572864, implicit-def $scc
+    ; GFX9: $sgpr33 = V_READLANE_B32_vi $vgpr2, 0
+    ; GFX9: $sgpr4 = S_ADD_U32 $sgpr33, 524544, implicit-def $scc
+    ; GFX9: $vgpr3 = BUFFER_LOAD_DWORD_OFFSET $sgpr0_sgpr1_sgpr2_sgpr3, killed $sgpr4, 0, 0, 0, 0, 0, 0, implicit $exec :: (load 4 from %stack.3, addrspace 5)
+    ; GFX9: S_ENDPGM 0, csr_amdgpu_allvgprs
+    $vgpr0 = V_OR_B32_e32 %stack.1, $vgpr1, implicit $exec
+    S_ENDPGM 0, csr_amdgpu_allvgprs
+...