[AMDGPU][CodeGen] Using MBB's liveIn check in tandem with MCRegAliasIterator in SILowerSGPRSpills

llvm/lib/Target/AMDGPU/SILowerSGPRSpills.cpp

@@ -101,6 +101,16 @@ INITIALIZE_PASS_END(SILowerSGPRSpillsLegacy, DEBUG_TYPE,
 
 char &llvm::SILowerSGPRSpillsLegacyID = SILowerSGPRSpillsLegacy::ID;
 
+static bool isLiveInIntoMBB(MCRegister Reg, MachineBasicBlock &MBB,
+                            const TargetRegisterInfo *TRI) {
+  for (MCRegAliasIterator R(Reg, TRI, true); R.isValid(); ++R) {
+    if (MBB.isLiveIn(*R)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 /// Insert spill code for the callee-saved registers used in the function.
 static void insertCSRSaves(MachineBasicBlock &SaveBlock,
                            ArrayRef<CalleeSavedInfo> CSI, SlotIndexes *Indexes,
@@ -114,8 +124,6 @@ static void insertCSRSaves(MachineBasicBlock &SaveBlock,
 
   MachineBasicBlock::iterator I = SaveBlock.begin();
   if (!TFI->spillCalleeSavedRegisters(SaveBlock, I, CSI, TRI)) {
-    const MachineRegisterInfo &MRI = MF.getRegInfo();
-
     for (const CalleeSavedInfo &CS : CSI) {
       // Insert the spill to the stack frame.
       MCRegister Reg = CS.getReg();
@@ -128,7 +136,7 @@ static void insertCSRSaves(MachineBasicBlock &SaveBlock,
       // incoming register value, so don't kill at the spill point. This happens
       // since we pass some special inputs (workgroup IDs) in the callee saved
       // range.
-      const bool IsLiveIn = MRI.isLiveIn(Reg);
+      bool IsLiveIn = isLiveInIntoMBB(Reg, SaveBlock, TRI);
       TII.storeRegToStackSlot(SaveBlock, I, Reg, !IsLiveIn, CS.getFrameIdx(),
                               RC, TRI, Register());
 

llvm/test/CodeGen/AMDGPU/spill-partial-csr-sgpr-live-ins.mir

@@ -1,25 +1,6 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: not --crash llc -mtriple=amdgcn-amd-amdhsa -verify-machineinstrs -run-pass=si-lower-sgpr-spills %s -o /dev/null 2>&1 | FileCheck -check-prefix=VERIFIER %s
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -verify-machineinstrs -run-pass=si-lower-sgpr-spills -o - %s | FileCheck %s
 
-# FIXME : Currently, MRI's liveIn check for registers does not take the corresponding live-in's sub-registers into account. As a result
-# in SILowerSGPRSpills, the SubReg spill gets marked KILLED even though its SuperReg is in the function Live-ins. This causes machine
-# verifier to now fail at direct usage of that SubReg, which intially should not be any problem before adding spill.
-
-# VERIFIER: After SI lower SGPR spill instructions
-
-# VERIFIER: *** Bad machine code: Using an undefined physical register ***
-# VERIFIER: - instruction: S_NOP 0, implicit $sgpr50
-# VERIFIER-NEXT: - operand 1:   implicit $sgpr50
-
-# VERIFIER: *** Bad machine code: Using an undefined physical register ***
-# VERIFIER: - instruction: S_NOP 0, implicit $sgpr52
-# VERIFIER-NEXT: - operand 1:   implicit $sgpr52
-
-# VERIFIER: *** Bad machine code: Using an undefined physical register ***
-# VERIFIER: - instruction: S_NOP 0, implicit $sgpr55
-# VERIFIER-NEXT: - operand 1:   implicit $sgpr55
-
-# VERIFIER: LLVM ERROR: Found 3 machine code errors. 
 ---
 name: spill_partial_live_csr_sgpr_test
 tracksRegLiveness: true
@@ -31,6 +12,21 @@ body:             |
   bb.0:
     liveins: $sgpr50_sgpr51, $sgpr52_sgpr53, $sgpr54_sgpr55
 
+    ; CHECK-LABEL: name: spill_partial_live_csr_sgpr_test
+    ; CHECK: liveins: $sgpr50, $sgpr52, $sgpr53, $sgpr54, $sgpr55, $vgpr63, $sgpr50_sgpr51, $sgpr52_sgpr53, $sgpr54_sgpr55
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr50, 0, $vgpr63
+    ; CHECK-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr52, 1, $vgpr63
+    ; CHECK-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr53, 2, $vgpr63
+    ; CHECK-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr54, 3, $vgpr63
+    ; CHECK-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr55, 4, $vgpr63
+    ; CHECK-NEXT: S_NOP 0, implicit $sgpr50
+    ; CHECK-NEXT: $sgpr50 = S_MOV_B32 0
+    ; CHECK-NEXT: S_NOP 0, implicit $sgpr52
+    ; CHECK-NEXT: $sgpr52_sgpr53 = S_MOV_B64 0
+    ; CHECK-NEXT: S_NOP 0, implicit $sgpr55
+    ; CHECK-NEXT: $sgpr54_sgpr55 = S_MOV_B64 0
+    ; CHECK-NEXT: $sgpr56 = S_MOV_B32 0
     S_NOP 0, implicit $sgpr50
     $sgpr50 = S_MOV_B32 0
     S_NOP 0, implicit $sgpr52

llvm/test/CodeGen/AMDGPU/spill-sgpr-to-virtual-vgpr.mir

@@ -55,22 +55,22 @@ body:             |
     ; GCN-LABEL: name: sgpr_spill_lane_crossover
     ; GCN: liveins: $sgpr10, $sgpr64, $sgpr65, $sgpr66, $sgpr67, $sgpr68, $sgpr69, $sgpr70, $sgpr71, $sgpr80, $sgpr81, $sgpr82, $sgpr83, $sgpr84, $sgpr85, $sgpr86, $sgpr87, $vgpr63, $sgpr30_sgpr31, $sgpr64_sgpr65_sgpr66_sgpr67_sgpr68_sgpr69_sgpr70_sgpr71, $sgpr72_sgpr73_sgpr74_sgpr75_sgpr76_sgpr77_sgpr78_sgpr79, $sgpr80_sgpr81_sgpr82_sgpr83_sgpr84_sgpr85_sgpr86_sgpr87, $sgpr88_sgpr89_sgpr90_sgpr91_sgpr92_sgpr93_sgpr94_sgpr95
     ; GCN-NEXT: {{  $}}
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr64, 0, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr65, 1, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr66, 2, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr67, 3, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr68, 4, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr69, 5, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr70, 6, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr71, 7, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr80, 8, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr81, 9, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr82, 10, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr83, 11, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr84, 12, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr85, 13, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr86, 14, $vgpr63
-    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR killed $sgpr87, 15, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr64, 0, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr65, 1, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr66, 2, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr67, 3, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr68, 4, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr69, 5, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr70, 6, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr71, 7, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr80, 8, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr81, 9, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr82, 10, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr83, 11, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr84, 12, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr85, 13, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr86, 14, $vgpr63
+    ; GCN-NEXT: $vgpr63 = SI_SPILL_S32_TO_VGPR $sgpr87, 15, $vgpr63
     ; GCN-NEXT: S_NOP 0
     ; GCN-NEXT: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
     ; GCN-NEXT: [[DEF:%[0-9]+]]:vgpr_32 = SI_SPILL_S32_TO_VGPR killed $sgpr10, 0, [[DEF]]