[llvm-branch-commits] [llvm] RegAlloc: Fix verifier error after failed allocation (PR #119690)

Matt Arsenault via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Thu Dec 12 02:49:52 PST 2024


https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/119690

>From bca529ad0b6fabe5825c3ed305b389d489f7e2c9 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Fri, 25 Mar 2022 20:27:39 -0400
Subject: [PATCH] RegAlloc: Fix verifier error after failed allocation

In some cases after reporting an allocation failure, this would fail
the verifier. It picks the first allocatable register and assigns it,
but didn't update the liveness appropriately. When VirtRegRewriter
relied on the liveness to set kill flags, it would incorrectly add
kill flags if there was another overlapping kill of the virtual
register.

We can't properly assign the register to an overlapping range, so
break the liveness of the failing register (and any other interfering
registers) instead. Give the virtual register dummy liveness by
effectively deleting all the uses by setting them to undef.

The edge case not tested here which I'm worried about is if the read
of the register is a def of a subregister. I've been unable to come up
with a test where this occurs.

https://reviews.llvm.org/D122616
---
 llvm/lib/CodeGen/RegAllocBase.cpp             | 36 +++++++++++
 llvm/lib/CodeGen/RegAllocBase.h               |  6 ++
 llvm/lib/CodeGen/RegAllocBasic.cpp            |  1 +
 llvm/lib/CodeGen/RegAllocGreedy.cpp           |  1 +
 .../AMDGPU/illegal-eviction-assert.mir        |  4 +-
 llvm/test/CodeGen/AMDGPU/issue48473.mir       |  3 +-
 ...ut-of-registers-error-all-regs-reserved.ll |  8 +--
 ...lloc-failure-overlapping-insert-assert.mir |  7 +--
 ...ster-killed-error-after-alloc-failure0.mir | 59 +++++++++++++++++++
 ...ister-killed-error-after-alloc-failure1.ll | 30 ++++++++++
 .../remaining-virtual-register-operands.ll    |  3 +-
 11 files changed, 143 insertions(+), 15 deletions(-)
 create mode 100644 llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure0.mir
 create mode 100644 llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure1.ll

diff --git a/llvm/lib/CodeGen/RegAllocBase.cpp b/llvm/lib/CodeGen/RegAllocBase.cpp
index 980a6756963d9f..bb0c8a32a7bc92 100644
--- a/llvm/lib/CodeGen/RegAllocBase.cpp
+++ b/llvm/lib/CodeGen/RegAllocBase.cpp
@@ -65,6 +65,7 @@ void RegAllocBase::init(VirtRegMap &vrm, LiveIntervals &lis,
   Matrix = &mat;
   MRI->freezeReservedRegs();
   RegClassInfo.runOnMachineFunction(vrm.getMachineFunction());
+  FailedVRegs.clear();
 }
 
 // Visit all the live registers. If they are already assigned to a physical
@@ -128,6 +129,7 @@ void RegAllocBase::allocatePhysRegs() {
 
       // Keep going after reporting the error.
       VRM->assignVirt2Phys(VirtReg->reg(), AvailablePhysReg);
+      FailedVRegs.insert(VirtReg->reg());
     } else if (AvailablePhysReg)
       Matrix->assign(*VirtReg, AvailablePhysReg);
 
@@ -161,6 +163,40 @@ void RegAllocBase::postOptimization() {
   DeadRemats.clear();
 }
 
+void RegAllocBase::cleanupFailedVRegs() {
+  SmallSet<Register, 8> JunkRegs;
+
+  for (Register FailedReg : FailedVRegs) {
+    JunkRegs.insert(FailedReg);
+
+    MCRegister PhysReg = VRM->getPhys(FailedReg);
+    LiveInterval &FailedInterval = LIS->getInterval(FailedReg);
+
+    // The liveness information for the failed register and anything interfering
+    // with the physical register we arbitrarily chose is junk and needs to be
+    // deleted.
+    for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
+      LiveIntervalUnion::Query &Q = Matrix->query(FailedInterval, *Units);
+      for (const LiveInterval *InterferingReg : Q.interferingVRegs())
+        JunkRegs.insert(InterferingReg->reg());
+    }
+  }
+
+  // TODO: Probably need to set undef on any physreg uses not associated with
+  // a virtual register.
+  for (Register JunkReg : JunkRegs) {
+    // We still should produce valid IR. Kill all the uses and reduce the live
+    // ranges so that we don't think it's possible to introduce kill flags
+    // later which will fail the verifier.
+    for (MachineOperand &MO : MRI->reg_operands(JunkReg)) {
+      if (MO.readsReg())
+        MO.setIsUndef(true);
+    }
+
+    LIS->shrinkToUses(&LIS->getInterval(JunkReg));
+  }
+}
+
 void RegAllocBase::enqueue(const LiveInterval *LI) {
   const Register Reg = LI->reg();
 
diff --git a/llvm/lib/CodeGen/RegAllocBase.h b/llvm/lib/CodeGen/RegAllocBase.h
index 5bd52da61f2dc5..1fdbab694bb0e3 100644
--- a/llvm/lib/CodeGen/RegAllocBase.h
+++ b/llvm/lib/CodeGen/RegAllocBase.h
@@ -37,6 +37,7 @@
 #define LLVM_LIB_CODEGEN_REGALLOCBASE_H
 
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegAllocCommon.h"
 #include "llvm/CodeGen/RegisterClassInfo.h"
@@ -81,6 +82,7 @@ class RegAllocBase {
   /// always available for the remat of all the siblings of the original reg.
   SmallPtrSet<MachineInstr *, 32> DeadRemats;
 
+  SmallSet<Register, 2> FailedVRegs;
   RegAllocBase(const RegAllocFilterFunc F = nullptr)
       : shouldAllocateRegisterImpl(F) {}
 
@@ -104,6 +106,10 @@ class RegAllocBase {
   // rematerialization.
   virtual void postOptimization();
 
+  /// Perform cleanups on registers that failed to allocate. This hacks on the
+  /// liveness in order to avoid spurious verifier errors in later passes.
+  void cleanupFailedVRegs();
+
   // Get a temporary reference to a Spiller instance.
   virtual Spiller &spiller() = 0;
 
diff --git a/llvm/lib/CodeGen/RegAllocBasic.cpp b/llvm/lib/CodeGen/RegAllocBasic.cpp
index c05aa1e40e4779..7393267c24980b 100644
--- a/llvm/lib/CodeGen/RegAllocBasic.cpp
+++ b/llvm/lib/CodeGen/RegAllocBasic.cpp
@@ -323,6 +323,7 @@ bool RABasic::runOnMachineFunction(MachineFunction &mf) {
 
   allocatePhysRegs();
   postOptimization();
+  cleanupFailedVRegs();
 
   // Diagnostic output before rewriting
   LLVM_DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *VRM << "\n");
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index af48e916feab45..f746762b223818 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -2772,6 +2772,7 @@ bool RAGreedy::runOnMachineFunction(MachineFunction &mf) {
   if (VerifyEnabled)
     MF->verify(this, "Before post optimization", &errs());
   postOptimization();
+  cleanupFailedVRegs();
   reportStats();
 
   releaseMemory();
diff --git a/llvm/test/CodeGen/AMDGPU/illegal-eviction-assert.mir b/llvm/test/CodeGen/AMDGPU/illegal-eviction-assert.mir
index 99c27fa0bc95c4..443d1e9d1bdf08 100644
--- a/llvm/test/CodeGen/AMDGPU/illegal-eviction-assert.mir
+++ b/llvm/test/CodeGen/AMDGPU/illegal-eviction-assert.mir
@@ -17,8 +17,8 @@
 
 ...
 
-# CHECK: S_NOP 0, implicit-def renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19, implicit-def renamable $vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27, implicit-def renamable $vgpr0_vgpr1_vgpr2_vgpr3, implicit-def renamable $vgpr28_vgpr29_vgpr30_vgpr31, implicit-def renamable $vgpr0_vgpr1_vgpr2_vgpr3
-# CHECK: S_NOP 0, implicit killed renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19, implicit killed renamable $vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27, implicit killed renamable $vgpr0_vgpr1_vgpr2_vgpr3, implicit killed renamable $vgpr28_vgpr29_vgpr30_vgpr31, implicit killed renamable $vgpr0_vgpr1_vgpr2_vgpr3
+# CHECK: S_NOP 0, implicit-def renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19, implicit-def renamable $vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27, implicit-def dead renamable $vgpr0_vgpr1_vgpr2_vgpr3, implicit-def renamable $vgpr28_vgpr29_vgpr30_vgpr31, implicit-def dead renamable $vgpr0_vgpr1_vgpr2_vgpr3
+# CHECK: S_NOP 0, implicit killed renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19, implicit killed renamable $vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3, implicit killed renamable $vgpr28_vgpr29_vgpr30_vgpr31, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3
 
 ---
 name:            foo
diff --git a/llvm/test/CodeGen/AMDGPU/issue48473.mir b/llvm/test/CodeGen/AMDGPU/issue48473.mir
index e272bd34803831..ba03855d01cd9b 100644
--- a/llvm/test/CodeGen/AMDGPU/issue48473.mir
+++ b/llvm/test/CodeGen/AMDGPU/issue48473.mir
@@ -43,7 +43,8 @@
 # %25 to $sgpr60_sgpr61_sgpr62_sgpr63_sgpr64_sgpr65_sgpr66_sgpr67
 
 # CHECK-LABEL: name: issue48473
-# CHECK: S_NOP 0, implicit killed renamable $sgpr0_sgpr1_sgpr2_sgpr3, implicit killed renamable $sgpr12_sgpr13_sgpr14_sgpr15, implicit killed renamable $sgpr16_sgpr17_sgpr18_sgpr19_sgpr20_sgpr21_sgpr22_sgpr23, implicit killed renamable $sgpr24_sgpr25_sgpr26_sgpr27_sgpr28_sgpr29_sgpr30_sgpr31, implicit killed renamable $sgpr84_sgpr85_sgpr86_sgpr87, implicit killed renamable $sgpr36_sgpr37_sgpr38_sgpr39_sgpr40_sgpr41_sgpr42_sgpr43, implicit killed renamable $sgpr4_sgpr5_sgpr6_sgpr7, implicit killed renamable $sgpr44_sgpr45_sgpr46_sgpr47_sgpr48_sgpr49_sgpr50_sgpr51, implicit killed renamable $sgpr88_sgpr89_sgpr90_sgpr91, implicit killed renamable $sgpr76_sgpr77_sgpr78_sgpr79_sgpr80_sgpr81_sgpr82_sgpr83, implicit killed renamable $sgpr0_sgpr1_sgpr2_sgpr3, implicit killed renamable $sgpr52_sgpr53_sgpr54_sgpr55_sgpr56_sgpr57_sgpr58_sgpr59, implicit killed renamable $sgpr92_sgpr93_sgpr94_sgpr95, implicit killed renamable $sgpr68_sgpr69_sgpr70_sgpr71_sgpr72_sgpr73_sgpr74_sgpr75, implicit renamable $sgpr68_sgpr69_sgpr70_sgpr71_sgpr72_sgpr73_sgpr74_sgpr75, implicit killed renamable $sgpr96_sgpr97_sgpr98_sgpr99, implicit killed renamable $sgpr8_sgpr9_sgpr10_sgpr11, implicit killed renamable $sgpr60_sgpr61_sgpr62_sgpr63_sgpr64_sgpr65_sgpr66_sgpr67
+# CHECK: S_NOP 0, implicit undef renamable $sgpr0_sgpr1_sgpr2_sgpr3, implicit killed renamable $sgpr12_sgpr13_sgpr14_sgpr15, implicit killed renamable $sgpr16_sgpr17_sgpr18_sgpr19_sgpr20_sgpr21_sgpr22_sgpr23, implicit killed renamable $sgpr24_sgpr25_sgpr26_sgpr27_sgpr28_sgpr29_sgpr30_sgpr31, implicit killed renamable $sgpr84_sgpr85_sgpr86_sgpr87, implicit killed renamable $sgpr36_sgpr37_sgpr38_sgpr39_sgpr40_sgpr41_sgpr42_sgpr43, implicit killed renamable $sgpr4_sgpr5_sgpr6_sgpr7, implicit killed renamable $sgpr44_sgpr45_sgpr46_sgpr47_sgpr48_sgpr49_sgpr50_sgpr51, implicit killed renamable $sgpr88_sgpr89_sgpr90_sgpr91, implicit killed renamable $sgpr76_sgpr77_sgpr78_sgpr79_sgpr80_sgpr81_sgpr82_sgpr83, implicit undef renamable $sgpr0_sgpr1_sgpr2_sgpr3, implicit killed renamable $sgpr52_sgpr53_sgpr54_sgpr55_sgpr56_sgpr57_sgpr58_sgpr59, implicit killed renamable $sgpr92_sgpr93_sgpr94_sgpr95, implicit killed renamable $sgpr68_sgpr69_sgpr70_sgpr71_sgpr72_sgpr73_sgpr74_sgpr75, implicit renamable $sgpr68_sgpr69_sgpr70_sgpr71_sgpr72_sgpr73_sgpr74_sgpr75, implicit killed renamable $sgpr96_sgpr97_sgpr98_sgpr99, implicit killed renamable $sgpr8_sgpr9_sgpr10_sgpr11, implicit killed renamable $sgpr60_sgpr61_sgpr62_sgpr63_sgpr64_sgpr65_sgpr66_sgpr67
+
 
 ---
 name:            issue48473
diff --git a/llvm/test/CodeGen/AMDGPU/ran-out-of-registers-error-all-regs-reserved.ll b/llvm/test/CodeGen/AMDGPU/ran-out-of-registers-error-all-regs-reserved.ll
index 388a8e804a8896..06c862c7fb481f 100644
--- a/llvm/test/CodeGen/AMDGPU/ran-out-of-registers-error-all-regs-reserved.ll
+++ b/llvm/test/CodeGen/AMDGPU/ran-out-of-registers-error-all-regs-reserved.ll
@@ -1,8 +1,6 @@
-; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -vgpr-regalloc=greedy -verify-machineinstrs=0 -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
-; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -vgpr-regalloc=basic -verify-machineinstrs=0 -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
-; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -vgpr-regalloc=fast -verify-machineinstrs=0 -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
-
-; FIXME: Should pass verifier after failure.
+; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -vgpr-regalloc=greedy -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
+; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -vgpr-regalloc=basic -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
+; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -vgpr-regalloc=fast -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
 
 declare <32 x i32> @llvm.amdgcn.mfma.i32.32x32x4i8(i32, i32, <32 x i32>, i32 immarg, i32 immarg, i32 immarg)
 
diff --git a/llvm/test/CodeGen/AMDGPU/regalloc-failure-overlapping-insert-assert.mir b/llvm/test/CodeGen/AMDGPU/regalloc-failure-overlapping-insert-assert.mir
index fe01728c005633..1e33f242668a60 100644
--- a/llvm/test/CodeGen/AMDGPU/regalloc-failure-overlapping-insert-assert.mir
+++ b/llvm/test/CodeGen/AMDGPU/regalloc-failure-overlapping-insert-assert.mir
@@ -1,10 +1,7 @@
-# RUN: not llc -mtriple=amdgcn -mcpu=gfx908 -verify-machineinstrs=0 -start-before=greedy,1 -stop-after=virtregrewriter,2 %s -o /dev/null 2>&1 | FileCheck -check-prefix=ERR %s
-# RUN: not --crash llc -mtriple=amdgcn -mcpu=gfx908 -verify-machineinstrs -start-before=greedy,1 -stop-after=virtregrewriter,2 %s -o /dev/null 2>&1 | FileCheck -check-prefixes=ERR,VERIFIER %s
-
-# FIXME: We should not produce a verifier error after erroring
+# RUN: not llc -mtriple=amdgcn -mcpu=gfx908 -verify-machineinstrs -start-before=greedy,1 -stop-after=virtregrewriter,1 %s -filetype=null 2>&1 | FileCheck -check-prefix=ERR %s
 
 # ERR: error: inline assembly requires more registers than available
-# VERIFIER: *** Bad machine code: Using an undefined physical register ***
+# ERR-NOT: Bad machine code
 
 # This testcase cannot be compiled with the enforced register
 # budget. Previously, tryLastChanceRecoloring would assert here. It
diff --git a/llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure0.mir b/llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure0.mir
new file mode 100644
index 00000000000000..15102d7ecb6662
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure0.mir
@@ -0,0 +1,59 @@
+# RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -vgpr-regalloc=basic -sgpr-regalloc=basic -start-before=regallocbasic,0 -stop-after=virtregrewriter,2 -verify-machineinstrs -o - %s 2> %t.basic.err | FileCheck -check-prefix=BASIC %s
+# RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -start-before=greedy,0 -stop-after=virtregrewriter,2 -verify-machineinstrs -o - %s 2> %t.greedy.err | FileCheck -check-prefix=GREEDY %s
+
+# RUN: FileCheck -check-prefix=ERR -implicit-check-not=error %s < %t.basic.err
+# RUN: FileCheck -check-prefix=ERR -implicit-check-not=error %s < %t.greedy.err
+
+# This testcase must fail register allocation. It should also not
+# produce a verifier error after doing so. Previously, it would not
+# properly update the liveness for the dummy selected register. As a
+# result, VirtRegRewriter would incorrectly add kill flags which
+# combined with other uses of the physical register produced a
+# verifier error.
+
+# ERR: error: <unknown>:0:0: ran out of registers during register allocation
+
+# GREEDY: SI_SPILL_V256_SAVE undef $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7
+# GREEDY-NEXT: SI_SPILL_V512_SAVE undef $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19
+# GREEDY-NEXT: SI_SPILL_V128_SAVE undef $vgpr0_vgpr1_vgpr2_vgpr3
+
+# GREEDY: dead renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19 = SI_SPILL_V512_RESTORE
+# GREEDY: dead renamable $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7 = SI_SPILL_V256_RESTORE
+# GREEDY: S_NOP 0, implicit undef renamable $vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3
+# GREEDY: S_NOP 0, implicit killed renamable $vgpr20_vgpr21
+
+
+# BASIC: SI_SPILL_V128_SAVE undef $vgpr0_vgpr1_vgpr2_vgpr3
+# BASIC: SI_SPILL_V256_SAVE killed $vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23
+# BASIC: SI_SPILL_V512_SAVE undef $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15
+# BASIC: SI_SPILL_V64_SAVE killed $vgpr0_vgpr1, %stack.1, $sgpr32, 0, implicit $exec :: (store (s64) into %stack.1, align 4, addrspace 5)
+# BASIC: dead renamable $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15 = SI_SPILL_V512_RESTORE
+# BASIC: renamable $vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23 = SI_SPILL_V256_RESTORE
+# BASIC: dead renamable $vgpr0_vgpr1_vgpr2_vgpr3 = SI_SPILL_V128_RESTORE
+# BASIC: S_NOP 0, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15, implicit killed renamable $vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23, implicit undef renamable $vgpr0_vgpr1_vgpr2_vgpr3
+# BASIC: renamable $vgpr0_vgpr1 = SI_SPILL_V64_RESTORE
+
+--- |
+  define void @killed_reg_after_regalloc_failure() #0 {
+    ret void
+  }
+
+  attributes #0 = { "amdgpu-waves-per-eu"="10,10" }
+
+...
+---
+name:            killed_reg_after_regalloc_failure
+tracksRegLiveness: true
+machineFunctionInfo:
+  scratchRSrcReg:  '$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
+    S_NOP 0, implicit-def %3:vreg_64
+    S_NOP 0, implicit %0, implicit %1, implicit %2
+    S_NOP 0, implicit %3
+    S_ENDPGM 0
+
+...
diff --git a/llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure1.ll b/llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure1.ll
new file mode 100644
index 00000000000000..5e466a9470fc53
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/register-killed-error-after-alloc-failure1.ll
@@ -0,0 +1,30 @@
+; RUN: not llc -mtriple=amdgcn -mcpu=gfx908 -verify-machineinstrs -filetype=null %s 2>&1 | FileCheck -check-prefix=ERR -implicit-check-not=error %s
+
+; ERR: error: inline assembly requires more registers than available
+; ERR-NOT: ERROR
+; ERR-NOT: Bad machine code
+
+; This test requires respecting undef on the spill source operand when
+; expanding the pseudos to avoid all verifier errors
+
+%asm.output = type { <16 x i32>, <8 x i32>, <4 x i32>, <3 x i32>, <3 x i32> }
+
+define void @foo(<32 x i32> addrspace(1)* %arg) #0 {
+  %agpr0 = call i32 asm sideeffect "; def $0","=${a0}"()
+  %asm = call %asm.output asm sideeffect "; def $0 $1 $2 $3 $4","=v,=v,=v,=v,=v"()
+  %vgpr0 = extractvalue %asm.output %asm, 0
+  %vgpr1 = extractvalue %asm.output %asm, 1
+  %vgpr2 = extractvalue %asm.output %asm, 2
+  %vgpr3 = extractvalue %asm.output %asm, 3
+  %vgpr4 = extractvalue %asm.output %asm, 4
+  call void asm sideeffect "; clobber", "~{a[0:31]},~{v[0:31]}"()
+  call void asm sideeffect "; use $0","v"(<16 x i32> %vgpr0)
+  call void asm sideeffect "; use $0","v"(<8 x i32> %vgpr1)
+  call void asm sideeffect "; use $0","v"(<4 x i32> %vgpr2)
+  call void asm sideeffect "; use $0","v"(<3 x i32> %vgpr3)
+  call void asm sideeffect "; use $0","v"(<3 x i32> %vgpr4)
+  call void asm sideeffect "; use $0","{a1}"(i32 %agpr0)
+  ret void
+}
+
+attributes #0 = { "amdgpu-waves-per-eu"="8,8" }
diff --git a/llvm/test/CodeGen/AMDGPU/remaining-virtual-register-operands.ll b/llvm/test/CodeGen/AMDGPU/remaining-virtual-register-operands.ll
index 8e3054cceb85b7..d09d6608b216eb 100644
--- a/llvm/test/CodeGen/AMDGPU/remaining-virtual-register-operands.ll
+++ b/llvm/test/CodeGen/AMDGPU/remaining-virtual-register-operands.ll
@@ -1,4 +1,4 @@
-; RUN: not --crash llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -verify-machineinstrs < %s 2>&1 | FileCheck %s
+; RUN: not llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -verify-machineinstrs -filetype=null %s 2>&1 | FileCheck -implicit-check-not=error %s
 
 ; This testcase fails register allocation at the same time it performs
 ; virtual register splitting (by introducing VGPR to AGPR copies). We
@@ -11,7 +11,6 @@
 ; it takes the first avialable register.
 
 ; CHECK: error: <unknown>:0:0: ran out of registers during register allocation
-; CHECK: Bad machine code: Using an undefined physical register
 define amdgpu_kernel void @alloc_failure_with_split_vregs(float %v0, float %v1) #0 {
   %agpr0 = call float asm sideeffect "; def $0", "=${a0}"()
   %agpr.vec = insertelement <16 x float> undef, float %agpr0, i32 0



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