Revert "[AArch64][SVE] Pair SVE fill/spill into LDP/STP with -msve-vector-bits=128." (#134997)

Reverts #134068

Caused a stage 2 build failure:
https://lab.llvm.org/buildbot/#/builders/41/builds/6016

```
FAILED: lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o 
/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage1.install/bin/clang++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage2/lib/Support -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/lib/Support -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage2/include -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/include -mcpu=neoverse-512tvb -mllvm -scalable-vectorization=preferred -mllvm -treat-scalable-fixed-error-as-warning=false -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -Werror=global-constructors -O3 -DNDEBUG -std=c++17 -UNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -MD -MT lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o -MF lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o.d -o lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o -c /home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/lib/Support/Caching.cpp
Opcode has unknown scale!
UNREACHABLE executed at ../llvm/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:4530!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage1.install/bin/clang++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage2/lib/Support -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/lib/Support -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage2/include -I/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/include -mcpu=neoverse-512tvb -mllvm -scalable-vectorization=preferred -mllvm -treat-scalable-fixed-error-as-warning=false -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -Werror=global-constructors -O3 -DNDEBUG -std=c++17 -UNDEBUG -fno-exceptions -funwind-tables -fno-rtti -MD -MT lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o -MF lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o.d -o lib/Support/CMakeFiles/LLVMSupport.dir/Caching.cpp.o -c /home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/lib/Support/Caching.cpp
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/llvm/llvm/lib/Support/Caching.cpp'.
4.	Running pass 'AArch64 load / store optimization pass' on function '@"_ZNSt17_Function_handlerIFN4llvm8ExpectedISt8functionIFNS1_ISt10unique_ptrINS0_16CachedFileStreamESt14default_deleteIS4_EEEEjRKNS0_5TwineEEEEEjNS0_9StringRefESB_EZNS0_10localCacheESB_SB_SB_S2_IFvjSB_S3_INS0_12MemoryBufferES5_ISH_EEEEE3$_0E9_M_invokeERKSt9_Any_dataOjOSF_SB_"'
 #0 0x0000b6eae9b67bf0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage1.install/bin/clang+++0x81c7bf0)
 #1 0x0000b6eae9b65aec llvm::sys::RunSignalHandlers() (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage1.install/bin/clang+++0x81c5aec)
 #2 0x0000b6eae9acd5f4 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x0000f16c1aff28f8 (linux-vdso.so.1+0x8f8)
 #4 0x0000f16c1aacf1f0 __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x0000f16c1aa8a67c gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #6 0x0000f16c1aa77130 abort ./stdlib/abort.c:81:7
 #7 0x0000b6eae9ad6628 (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage1.install/bin/clang+++0x8136628)
 #8 0x0000b6eae72e95a8 (/home/tcwg-buildbot/worker/clang-aarch64-sve-vla-2stage/stage1.install/bin/clang+++0x59495a8)
 #9 0x0000b6eae74ca9a8 (anonymous namespace)::AArch64LoadStoreOpt::findMatchingInsn(llvm::MachineInstrBundleIterator<llvm::MachineInstr, false>, (anonymous namespace)::LdStPairFlags&, unsigned int, bool) AArch64LoadStoreOptimizer.cpp:0:0
#10 0x0000b6eae74c85a8 (anonymous namespace)::AArch64LoadStoreOpt::tryToPairLdStInst(llvm::MachineInstrBundleIterator<llvm::MachineInstr, false>&) AArch64LoadStoreOptimizer.cpp:0:0
#11 0x0000b6eae74c624c (anonymous namespace)::AArch64LoadStoreOpt::optimizeBlock(llvm::MachineBasicBlock&, bool) AArch64LoadStoreOptimizer.cpp:0:0
#12 0x0000b6eae74c429c (anonymous namespace)::AArch64LoadStoreOpt::runOnMachineFunction(llvm::MachineFunction&) AArch64LoadStoreOptimizer.cpp:0:0
```

Author: DavidSpickett

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -2760,9 +2760,6 @@ bool AArch64InstrInfo::isPairableLdStInst(const MachineInstr &MI) {
   case AArch64::LDRXpre:
   case AArch64::LDURSWi:
   case AArch64::LDRSWpre:
-  // SVE instructions.
-  case AArch64::LDR_ZXI:
-  case AArch64::STR_ZXI:
     return true;
   }
 }
@@ -2915,18 +2912,6 @@ bool AArch64InstrInfo::isCandidateToMergeOrPair(const MachineInstr &MI) const {
       return false;
   }
 
-  // Pairing SVE fills/spills is only valid for little-endian targets that
-  // implement VLS 128.
-  switch (MI.getOpcode()) {
-  default:
-    break;
-  case AArch64::LDR_ZXI:
-  case AArch64::STR_ZXI:
-    if (!Subtarget.isLittleEndian() ||
-        Subtarget.getSVEVectorSizeInBits() != 128)
-      return false;
-  }
-
   // Check if this load/store has a hint to avoid pair formation.
   // MachineMemOperands hints are set by the AArch64StorePairSuppress pass.
   if (isLdStPairSuppressed(MI))

llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp

@@ -298,7 +298,6 @@ static unsigned getMatchingNonSExtOpcode(unsigned Opc,
   case AArch64::STRXui:
   case AArch64::STRXpre:
   case AArch64::STURXi:
-  case AArch64::STR_ZXI:
   case AArch64::LDRDui:
   case AArch64::LDURDi:
   case AArch64::LDRDpre:
@@ -317,7 +316,6 @@ static unsigned getMatchingNonSExtOpcode(unsigned Opc,
   case AArch64::LDRSui:
   case AArch64::LDURSi:
   case AArch64::LDRSpre:
-  case AArch64::LDR_ZXI:
     return Opc;
   case AArch64::LDRSWui:
     return AArch64::LDRWui;
@@ -363,7 +361,6 @@ static unsigned getMatchingPairOpcode(unsigned Opc) {
     return AArch64::STPDpre;
   case AArch64::STRQui:
   case AArch64::STURQi:
-  case AArch64::STR_ZXI:
     return AArch64::STPQi;
   case AArch64::STRQpre:
     return AArch64::STPQpre;
@@ -389,7 +386,6 @@ static unsigned getMatchingPairOpcode(unsigned Opc) {
     return AArch64::LDPDpre;
   case AArch64::LDRQui:
   case AArch64::LDURQi:
-  case AArch64::LDR_ZXI:
     return AArch64::LDPQi;
   case AArch64::LDRQpre:
     return AArch64::LDPQpre;
@@ -1229,16 +1225,6 @@ AArch64LoadStoreOpt::mergePairedInsns(MachineBasicBlock::iterator I,
     (void)MIBSXTW;
     LLVM_DEBUG(dbgs() << "  Extend operand:\n    ");
     LLVM_DEBUG(((MachineInstr *)MIBSXTW)->print(dbgs()));
-  } else if (Opc == AArch64::LDR_ZXI || Opc == AArch64::STR_ZXI) {
-    // We are combining SVE fill/spill to LDP/STP, so we need to use the Q
-    // variant of the registers.
-    MachineOperand &MOp0 = MIB->getOperand(0);
-    MachineOperand &MOp1 = MIB->getOperand(1);
-    assert(AArch64::ZPRRegClass.contains(MOp0.getReg()) &&
-           AArch64::ZPRRegClass.contains(MOp1.getReg()) && "Invalid register.");
-    MOp0.setReg(AArch64::Q0 + (MOp0.getReg() - AArch64::Z0));
-    MOp1.setReg(AArch64::Q0 + (MOp1.getReg() - AArch64::Z0));
-    LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
   } else {
     LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
   }
@@ -2673,8 +2659,7 @@ bool AArch64LoadStoreOpt::tryToPairLdStInst(MachineBasicBlock::iterator &MBBI) {
       // Get the needed alignments to check them if
       // ldp-aligned-only/stp-aligned-only features are opted.
       uint64_t MemAlignment = MemOp->getAlign().value();
-      uint64_t TypeAlignment =
-          Align(MemOp->getSize().getValue().getKnownMinValue()).value();
+      uint64_t TypeAlignment = Align(MemOp->getSize().getValue()).value();
 
       if (MemAlignment < 2 * TypeAlignment) {
         NumFailedAlignmentCheck++;
@@ -2835,18 +2820,11 @@ bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
     }
   // 3) Find loads and stores that can be merged into a single load or store
   //    pair instruction.
-  //    When compiling for SVE 128, also try to combine SVE fill/spill
-  //    instructions into LDP/STP.
   //      e.g.,
   //        ldr x0, [x2]
   //        ldr x1, [x2, #8]
   //        ; becomes
   //        ldp x0, x1, [x2]
-  //      e.g.,
-  //        ldr z0, [x2]
-  //        ldr z1, [x2, #1, mul vl]
-  //        ; becomes
-  //        ldp q0, q1, [x2]
 
   if (MBB.getParent()->getRegInfo().tracksLiveness()) {
     DefinedInBB.clear();