[llvm] [AArch64][SVE] Pair SVE fill/spill into LDP/STP with -msve-vector-bits=128. (PR #134068)

Ricardo Jesus via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 8 03:02:06 PDT 2025


https://github.com/rj-jesus updated https://github.com/llvm/llvm-project/pull/134068

>From 0918660aa1b359cfbcc148f9dacf594c5cf126b7 Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Tue, 1 Apr 2025 09:52:35 -0700
Subject: [PATCH 1/6] Add tests

---
 .../AArch64/aarch64-sve-fill-spill-pair.ll    | 231 ++++++++++++++++++
 1 file changed, 231 insertions(+)
 create mode 100644 llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll

diff --git a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
new file mode 100644
index 0000000000000..d78e882e8a268
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
@@ -0,0 +1,231 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve,ldp-aligned-only -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-LDPALIGNEDONLY
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve,stp-aligned-only -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-STPALIGNEDONLY
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve < %s | FileCheck %s --check-prefixes=CHECK-OFF
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=256 -aarch64-sve-vector-bits-max=256 < %s | FileCheck %s --check-prefixes=CHECK-OFF
+
+define void @nxv16i8(ptr %ldptr, ptr %stptr) {
+; CHECK-LABEL: nxv16i8:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr z0, [x0]
+; CHECK-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-NEXT:    str z0, [x1]
+; CHECK-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-NEXT:    ret
+;
+; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8:
+; CHECK-LDPALIGNEDONLY:       // %bb.0:
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-STPALIGNEDONLY-LABEL: nxv16i8:
+; CHECK-STPALIGNEDONLY:       // %bb.0:
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0]
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1]
+; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-OFF-LABEL: nxv16i8:
+; CHECK-OFF:       // %bb.0:
+; CHECK-OFF-NEXT:    ldr z0, [x0]
+; CHECK-OFF-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-OFF-NEXT:    str z0, [x1]
+; CHECK-OFF-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-OFF-NEXT:    ret
+  %vscale = tail call i64 @llvm.vscale()
+  %vl = shl nuw nsw i64 %vscale, 4
+  %ldptr2 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %vl
+  %stptr2 = getelementptr inbounds nuw i8, ptr %stptr, i64 %vl
+  %ld1 = load <vscale x 16 x i8>, ptr %ldptr, align 1
+  %ld2 = load <vscale x 16 x i8>, ptr %ldptr2, align 1
+  store <vscale x 16 x i8> %ld1, ptr %stptr, align 1
+  store <vscale x 16 x i8> %ld2, ptr %stptr2, align 1
+  ret void
+}
+
+define void @nxv16i8_max_range(ptr %ldptr, ptr %stptr) {
+; CHECK-LABEL: nxv16i8_max_range:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr z0, [x0, #-64, mul vl]
+; CHECK-NEXT:    ldr z1, [x0, #-63, mul vl]
+; CHECK-NEXT:    str z0, [x1, #63, mul vl]
+; CHECK-NEXT:    str z1, [x1, #64, mul vl]
+; CHECK-NEXT:    ret
+;
+; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_max_range:
+; CHECK-LDPALIGNEDONLY:       // %bb.0:
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0, #-64, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #-63, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1, #63, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #64, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-STPALIGNEDONLY-LABEL: nxv16i8_max_range:
+; CHECK-STPALIGNEDONLY:       // %bb.0:
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0, #-64, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #-63, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1, #63, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #64, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-OFF-LABEL: nxv16i8_max_range:
+; CHECK-OFF:       // %bb.0:
+; CHECK-OFF-NEXT:    ldr z0, [x0, #-64, mul vl]
+; CHECK-OFF-NEXT:    ldr z1, [x0, #-63, mul vl]
+; CHECK-OFF-NEXT:    str z0, [x1, #63, mul vl]
+; CHECK-OFF-NEXT:    str z1, [x1, #64, mul vl]
+; CHECK-OFF-NEXT:    ret
+  %vscale = tail call i64 @llvm.vscale()
+  %ldoff1 = mul i64 %vscale, -1024
+  %ldoff2 = mul i64 %vscale, -1008
+  %stoff1 = mul i64 %vscale, 1008
+  %stoff2 = mul i64 %vscale, 1024
+  %ldptr1 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %ldoff1
+  %ldptr2 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %ldoff2
+  %stptr1 = getelementptr inbounds nuw i8, ptr %stptr, i64 %stoff1
+  %stptr2 = getelementptr inbounds nuw i8, ptr %stptr, i64 %stoff2
+  %ld1 = load <vscale x 16 x i8>, ptr %ldptr1, align 1
+  %ld2 = load <vscale x 16 x i8>, ptr %ldptr2, align 1
+  store <vscale x 16 x i8> %ld1, ptr %stptr1, align 1
+  store <vscale x 16 x i8> %ld2, ptr %stptr2, align 1
+  ret void
+}
+
+define void @nxv16i8_outside_range(ptr %ldptr, ptr %stptr) {
+; CHECK-LABEL: nxv16i8_outside_range:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr z0, [x0, #-65, mul vl]
+; CHECK-NEXT:    ldr z1, [x0, #-64, mul vl]
+; CHECK-NEXT:    str z0, [x1, #64, mul vl]
+; CHECK-NEXT:    str z1, [x1, #65, mul vl]
+; CHECK-NEXT:    ret
+;
+; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_outside_range:
+; CHECK-LDPALIGNEDONLY:       // %bb.0:
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0, #-65, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #-64, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1, #64, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #65, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-STPALIGNEDONLY-LABEL: nxv16i8_outside_range:
+; CHECK-STPALIGNEDONLY:       // %bb.0:
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0, #-65, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #-64, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1, #64, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #65, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-OFF-LABEL: nxv16i8_outside_range:
+; CHECK-OFF:       // %bb.0:
+; CHECK-OFF-NEXT:    ldr z0, [x0, #-65, mul vl]
+; CHECK-OFF-NEXT:    ldr z1, [x0, #-64, mul vl]
+; CHECK-OFF-NEXT:    str z0, [x1, #64, mul vl]
+; CHECK-OFF-NEXT:    str z1, [x1, #65, mul vl]
+; CHECK-OFF-NEXT:    ret
+  %vscale = tail call i64 @llvm.vscale()
+  %ldoff1 = mul i64 %vscale, -1040
+  %ldoff2 = mul i64 %vscale, -1024
+  %stoff1 = mul i64 %vscale, 1024
+  %stoff2 = mul i64 %vscale, 1040
+  %ldptr1 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %ldoff1
+  %ldptr2 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %ldoff2
+  %stptr1 = getelementptr inbounds nuw i8, ptr %stptr, i64 %stoff1
+  %stptr2 = getelementptr inbounds nuw i8, ptr %stptr, i64 %stoff2
+  %ld1 = load <vscale x 16 x i8>, ptr %ldptr1, align 1
+  %ld2 = load <vscale x 16 x i8>, ptr %ldptr2, align 1
+  store <vscale x 16 x i8> %ld1, ptr %stptr1, align 1
+  store <vscale x 16 x i8> %ld2, ptr %stptr2, align 1
+  ret void
+}
+
+define void @nxv16i8_2vl_stride(ptr %ldptr, ptr %stptr) {
+; CHECK-LABEL: nxv16i8_2vl_stride:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr z0, [x0]
+; CHECK-NEXT:    ldr z1, [x0, #2, mul vl]
+; CHECK-NEXT:    str z0, [x1]
+; CHECK-NEXT:    str z1, [x1, #2, mul vl]
+; CHECK-NEXT:    ret
+;
+; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_2vl_stride:
+; CHECK-LDPALIGNEDONLY:       // %bb.0:
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #2, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #2, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-STPALIGNEDONLY-LABEL: nxv16i8_2vl_stride:
+; CHECK-STPALIGNEDONLY:       // %bb.0:
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0]
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #2, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1]
+; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #2, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-OFF-LABEL: nxv16i8_2vl_stride:
+; CHECK-OFF:       // %bb.0:
+; CHECK-OFF-NEXT:    ldr z0, [x0]
+; CHECK-OFF-NEXT:    ldr z1, [x0, #2, mul vl]
+; CHECK-OFF-NEXT:    str z0, [x1]
+; CHECK-OFF-NEXT:    str z1, [x1, #2, mul vl]
+; CHECK-OFF-NEXT:    ret
+  %vscale = tail call i64 @llvm.vscale()
+  %vl = shl nuw nsw i64 %vscale, 5
+  %ldptr2 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %vl
+  %stptr2 = getelementptr inbounds nuw i8, ptr %stptr, i64 %vl
+  %ld1 = load <vscale x 16 x i8>, ptr %ldptr, align 1
+  %ld2 = load <vscale x 16 x i8>, ptr %ldptr2, align 1
+  store <vscale x 16 x i8> %ld1, ptr %stptr, align 1
+  store <vscale x 16 x i8> %ld2, ptr %stptr2, align 1
+  ret void
+}
+
+define void @nxv2f64_32b_aligned(ptr %ldptr, ptr %stptr) {
+; CHECK-LABEL: nxv2f64_32b_aligned:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ldr z0, [x0]
+; CHECK-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-NEXT:    str z0, [x1]
+; CHECK-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-NEXT:    ret
+;
+; CHECK-LDPALIGNEDONLY-LABEL: nxv2f64_32b_aligned:
+; CHECK-LDPALIGNEDONLY:       // %bb.0:
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
+; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1]
+; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-STPALIGNEDONLY-LABEL: nxv2f64_32b_aligned:
+; CHECK-STPALIGNEDONLY:       // %bb.0:
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0]
+; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1]
+; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ret
+;
+; CHECK-OFF-LABEL: nxv2f64_32b_aligned:
+; CHECK-OFF:       // %bb.0:
+; CHECK-OFF-NEXT:    ldr z0, [x0]
+; CHECK-OFF-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-OFF-NEXT:    str z0, [x1]
+; CHECK-OFF-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-OFF-NEXT:    ret
+  %vscale = tail call i64 @llvm.vscale()
+  %vl = shl nuw nsw i64 %vscale, 4
+  %ldptr2 = getelementptr inbounds nuw i8, ptr %ldptr, i64 %vl
+  %stptr2 = getelementptr inbounds nuw i8, ptr %stptr, i64 %vl
+  %ld1 = load <vscale x 2 x double>, ptr %ldptr, align 32
+  %ld2 = load <vscale x 2 x double>, ptr %ldptr2, align 32
+  store <vscale x 2 x double> %ld1, ptr %stptr, align 32
+  store <vscale x 2 x double> %ld2, ptr %stptr2, align 32
+  ret void
+}

>From c71d9cd776f847366a564bf314b02344a2410719 Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Tue, 25 Mar 2025 03:00:34 -0700
Subject: [PATCH 2/6] [AArch64][SVE] Pair SVE fill/spill into LDP/STP with
 -msve-vector-bits=128.

When compiling with -msve-vector-bits=128 or vscale_range(1, 1) and when
the offsets allow it, we can pair SVE LDR/STR instructions into Neon
LDP/STP.

For example, given:
```cpp

void foo(double const *ldp, double *stp) {
  svbool_t pg = svptrue_b64();
  svfloat64_t ld1 = svld1_f64(pg, ldp);
  svfloat64_t ld2 = svld1_f64(pg, ldp+svcntd());
  svst1_f64(pg, stp, ld1);
  svst1_f64(pg, stp+svcntd(), ld2);
}
```

When compiled with `-msve-vector-bits=128`, we currently generate:
```gas
foo:
        ldr     z0, [x0]
        ldr     z1, [x0, #1, mul vl]
        str     z0, [x1]
        str     z1, [x1, #1, mul vl]
        ret
```

With this patch, we instead generate:
```gas
foo:
        ldp     q0, q1, [x0]
        stp     q0, q1, [x1]
        ret
```

Loading (and to a lesser extent, storing) multiple registers from a
common base address is a commonly occurring pattern, but multi-register
SVE loads/stores are only supported starting with SVE2.1. This patch
offers an alternative for SVE 128-bit implementations.
---
 .../AArch64/AArch64LoadStoreOptimizer.cpp     | 48 ++++++++++++++++++-
 .../AArch64/aarch64-sve-fill-spill-pair.ll    | 43 ++++++-----------
 2 files changed, 62 insertions(+), 29 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index cd976790ebb6f..f1f1f66e12216 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -87,6 +87,10 @@ static cl::opt<unsigned> LdStConstLimit("aarch64-load-store-const-scan-limit",
 static cl::opt<bool> EnableRenaming("aarch64-load-store-renaming",
                                     cl::init(true), cl::Hidden);
 
+// Enable SVE fill/spill pairing for VLS 128.
+static cl::opt<bool> EnableSVEFillSpillPairing("aarch64-sve-fill-spill-pairing",
+                                               cl::init(true), cl::Hidden);
+
 #define AARCH64_LOAD_STORE_OPT_NAME "AArch64 load / store optimization pass"
 
 namespace {
@@ -97,6 +101,9 @@ using LdStPairFlags = struct LdStPairFlags {
   // a pair-wise insn, and false if the reverse is true.
   bool MergeForward = false;
 
+  // Set to true when pairing SVE fill/spill instructions.
+  bool SVEFillSpillPair = false;
+
   // SExtIdx gives the index of the result of the load pair that must be
   // extended. The value of SExtIdx assumes that the paired load produces the
   // value in this order: (I, returned iterator), i.e., -1 means no value has
@@ -113,6 +120,9 @@ using LdStPairFlags = struct LdStPairFlags {
   void setMergeForward(bool V = true) { MergeForward = V; }
   bool getMergeForward() const { return MergeForward; }
 
+  void setSVEFillSpillPair(bool V = true) { SVEFillSpillPair = V; }
+  bool getSVEFillSpillPair() const { return SVEFillSpillPair; }
+
   void setSExtIdx(int V) { SExtIdx = V; }
   int getSExtIdx() const { return SExtIdx; }
 
@@ -300,6 +310,7 @@ 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:
@@ -318,6 +329,7 @@ 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;
@@ -363,6 +375,7 @@ 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;
@@ -388,6 +401,7 @@ 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;
@@ -833,6 +847,12 @@ static bool isMergeableIndexLdSt(MachineInstr &MI, int &Scale) {
   }
 }
 
+// Return true if MI is an SVE fill/spill instruction.
+static bool isPairableFillSpillInst(const MachineInstr &MI) {
+  auto const Opc = MI.getOpcode();
+  return Opc == AArch64::LDR_ZXI || Opc == AArch64::STR_ZXI;
+}
+
 static bool isRewritableImplicitDef(unsigned Opc) {
   switch (Opc) {
   default:
@@ -1227,6 +1247,15 @@ AArch64LoadStoreOpt::mergePairedInsns(MachineBasicBlock::iterator I,
     (void)MIBSXTW;
     LLVM_DEBUG(dbgs() << "  Extend operand:\n    ");
     LLVM_DEBUG(((MachineInstr *)MIBSXTW)->print(dbgs()));
+  } else if (Flags.getSVEFillSpillPair()) {
+    // We are combining SVE fill/spill to LDP/STP, so we need to get 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));
   } else {
     LLVM_DEBUG(((MachineInstr *)MIB)->print(dbgs()));
   }
@@ -1829,6 +1858,9 @@ AArch64LoadStoreOpt::findMatchingInsn(MachineBasicBlock::iterator I,
 
   Flags.clearRenameReg();
 
+  if (isPairableFillSpillInst(FirstMI))
+    Flags.setSVEFillSpillPair();
+
   // Track which register units have been modified and used between the first
   // insn (inclusive) and the second insn.
   ModifiedRegUnits.clear();
@@ -2661,7 +2693,8 @@ 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()).value();
+      uint64_t TypeAlignment =
+          Align(MemOp->getSize().getValue().getKnownMinValue()).value();
 
       if (MemAlignment < 2 * TypeAlignment) {
         NumFailedAlignmentCheck++;
@@ -2782,6 +2815,9 @@ bool AArch64LoadStoreOpt::tryToMergeIndexLdSt(MachineBasicBlock::iterator &MBBI,
 bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
                                         bool EnableNarrowZeroStOpt) {
   AArch64FunctionInfo &AFI = *MBB.getParent()->getInfo<AArch64FunctionInfo>();
+  bool const CanPairFillSpill = EnableSVEFillSpillPairing &&
+                                Subtarget->isSVEorStreamingSVEAvailable() &&
+                                Subtarget->getSVEVectorSizeInBits() == 128;
 
   bool Modified = false;
   // Four tranformations to do here:
@@ -2822,11 +2858,18 @@ 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();
@@ -2840,6 +2883,9 @@ bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
     updateDefinedRegisters(*MBBI, DefinedInBB, TRI);
     if (TII->isPairableLdStInst(*MBBI) && tryToPairLdStInst(MBBI))
       Modified = true;
+    else if (CanPairFillSpill && isPairableFillSpillInst(*MBBI) &&
+             tryToPairLdStInst(MBBI))
+      Modified = true;
     else
       ++MBBI;
   }
diff --git a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
index d78e882e8a268..79120bc5352aa 100644
--- a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
+++ b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
@@ -4,28 +4,25 @@
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve,stp-aligned-only -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-STPALIGNEDONLY
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve < %s | FileCheck %s --check-prefixes=CHECK-OFF
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=256 -aarch64-sve-vector-bits-max=256 < %s | FileCheck %s --check-prefixes=CHECK-OFF
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 -aarch64-sve-fill-spill-pairing=0 < %s | FileCheck %s --check-prefixes=CHECK-OFF
 
 define void @nxv16i8(ptr %ldptr, ptr %stptr) {
 ; CHECK-LABEL: nxv16i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ldr z0, [x0]
-; CHECK-NEXT:    ldr z1, [x0, #1, mul vl]
-; CHECK-NEXT:    str z0, [x1]
-; CHECK-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-NEXT:    ldp q0, q1, [x0]
+; CHECK-NEXT:    stp q0, q1, [x1]
 ; CHECK-NEXT:    ret
 ;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
-; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1]
-; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    stp q0, q1, [x1]
 ; CHECK-LDPALIGNEDONLY-NEXT:    ret
 ;
 ; CHECK-STPALIGNEDONLY-LABEL: nxv16i8:
 ; CHECK-STPALIGNEDONLY:       // %bb.0:
-; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0]
-; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ldp q0, q1, [x0]
 ; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1]
 ; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
 ; CHECK-STPALIGNEDONLY-NEXT:    ret
@@ -51,24 +48,20 @@ define void @nxv16i8(ptr %ldptr, ptr %stptr) {
 define void @nxv16i8_max_range(ptr %ldptr, ptr %stptr) {
 ; CHECK-LABEL: nxv16i8_max_range:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ldr z0, [x0, #-64, mul vl]
-; CHECK-NEXT:    ldr z1, [x0, #-63, mul vl]
-; CHECK-NEXT:    str z0, [x1, #63, mul vl]
-; CHECK-NEXT:    str z1, [x1, #64, mul vl]
+; CHECK-NEXT:    ldp q0, q1, [x0, #-1024]
+; CHECK-NEXT:    stp q0, q1, [x1, #1008]
 ; CHECK-NEXT:    ret
 ;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_max_range:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0, #-64, mul vl]
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #-63, mul vl]
-; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1, #63, mul vl]
-; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #64, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    stp q0, q1, [x1, #1008]
 ; CHECK-LDPALIGNEDONLY-NEXT:    ret
 ;
 ; CHECK-STPALIGNEDONLY-LABEL: nxv16i8_max_range:
 ; CHECK-STPALIGNEDONLY:       // %bb.0:
-; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0, #-64, mul vl]
-; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #-63, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ldp q0, q1, [x0, #-1024]
 ; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1, #63, mul vl]
 ; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #64, mul vl]
 ; CHECK-STPALIGNEDONLY-NEXT:    ret
@@ -190,26 +183,20 @@ define void @nxv16i8_2vl_stride(ptr %ldptr, ptr %stptr) {
 define void @nxv2f64_32b_aligned(ptr %ldptr, ptr %stptr) {
 ; CHECK-LABEL: nxv2f64_32b_aligned:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    ldr z0, [x0]
-; CHECK-NEXT:    ldr z1, [x0, #1, mul vl]
-; CHECK-NEXT:    str z0, [x1]
-; CHECK-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-NEXT:    ldp q0, q1, [x0]
+; CHECK-NEXT:    stp q0, q1, [x1]
 ; CHECK-NEXT:    ret
 ;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv2f64_32b_aligned:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
-; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
-; CHECK-LDPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
-; CHECK-LDPALIGNEDONLY-NEXT:    str z0, [x1]
-; CHECK-LDPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-LDPALIGNEDONLY-NEXT:    ldp q0, q1, [x0]
+; CHECK-LDPALIGNEDONLY-NEXT:    stp q0, q1, [x1]
 ; CHECK-LDPALIGNEDONLY-NEXT:    ret
 ;
 ; CHECK-STPALIGNEDONLY-LABEL: nxv2f64_32b_aligned:
 ; CHECK-STPALIGNEDONLY:       // %bb.0:
-; CHECK-STPALIGNEDONLY-NEXT:    ldr z0, [x0]
-; CHECK-STPALIGNEDONLY-NEXT:    ldr z1, [x0, #1, mul vl]
-; CHECK-STPALIGNEDONLY-NEXT:    str z0, [x1]
-; CHECK-STPALIGNEDONLY-NEXT:    str z1, [x1, #1, mul vl]
+; CHECK-STPALIGNEDONLY-NEXT:    ldp q0, q1, [x0]
+; CHECK-STPALIGNEDONLY-NEXT:    stp q0, q1, [x1]
 ; CHECK-STPALIGNEDONLY-NEXT:    ret
 ;
 ; CHECK-OFF-LABEL: nxv2f64_32b_aligned:

>From 19cd626eb4f880164c536898d537aa7e0c1d1b92 Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Mon, 7 Apr 2025 06:26:53 -0700
Subject: [PATCH 3/6] Address comments

---
 .../AArch64/AArch64LoadStoreOptimizer.cpp     | 10 +--
 .../AArch64/aarch64-sve-fill-spill-pair.ll    | 68 ++++++++++++++++++-
 2 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index f1f1f66e12216..b1240b3709c17 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -87,9 +87,10 @@ static cl::opt<unsigned> LdStConstLimit("aarch64-load-store-const-scan-limit",
 static cl::opt<bool> EnableRenaming("aarch64-load-store-renaming",
                                     cl::init(true), cl::Hidden);
 
-// Enable SVE fill/spill pairing for VLS 128.
-static cl::opt<bool> EnableSVEFillSpillPairing("aarch64-sve-fill-spill-pairing",
-                                               cl::init(true), cl::Hidden);
+// Disable SVE fill/spill pairing for VLS 128.
+static cl::opt<bool>
+    DisableSVEFillSpillPairing("aarch64-disable-sve-fill-spill-pairing",
+                               cl::init(false), cl::Hidden);
 
 #define AARCH64_LOAD_STORE_OPT_NAME "AArch64 load / store optimization pass"
 
@@ -2815,7 +2816,8 @@ bool AArch64LoadStoreOpt::tryToMergeIndexLdSt(MachineBasicBlock::iterator &MBBI,
 bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
                                         bool EnableNarrowZeroStOpt) {
   AArch64FunctionInfo &AFI = *MBB.getParent()->getInfo<AArch64FunctionInfo>();
-  bool const CanPairFillSpill = EnableSVEFillSpillPairing &&
+  bool const CanPairFillSpill = !DisableSVEFillSpillPairing &&
+                                Subtarget->isLittleEndian() &&
                                 Subtarget->isSVEorStreamingSVEAvailable() &&
                                 Subtarget->getSVEVectorSizeInBits() == 128;
 
diff --git a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
index 79120bc5352aa..a06af29fbc5ee 100644
--- a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
+++ b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
@@ -1,10 +1,11 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s
+; RUN: llc -verify-machineinstrs -mtriple=aarch64_be-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-BE
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve,ldp-aligned-only -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-LDPALIGNEDONLY
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve,stp-aligned-only -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-STPALIGNEDONLY
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve < %s | FileCheck %s --check-prefixes=CHECK-OFF
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=256 -aarch64-sve-vector-bits-max=256 < %s | FileCheck %s --check-prefixes=CHECK-OFF
-; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 -aarch64-sve-fill-spill-pairing=0 < %s | FileCheck %s --check-prefixes=CHECK-OFF
+; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 -aarch64-disable-sve-fill-spill-pairing=1 < %s | FileCheck %s --check-prefixes=CHECK-OFF
 
 define void @nxv16i8(ptr %ldptr, ptr %stptr) {
 ; CHECK-LABEL: nxv16i8:
@@ -13,6 +14,15 @@ define void @nxv16i8(ptr %ldptr, ptr %stptr) {
 ; CHECK-NEXT:    stp q0, q1, [x1]
 ; CHECK-NEXT:    ret
 ;
+; CHECK-BE-LABEL: nxv16i8:
+; CHECK-BE:       // %bb.0:
+; CHECK-BE-NEXT:    ptrue p0.b
+; CHECK-BE-NEXT:    ld1b { z0.b }, p0/z, [x0]
+; CHECK-BE-NEXT:    ld1b { z1.b }, p0/z, [x0, #1, mul vl]
+; CHECK-BE-NEXT:    st1b { z0.b }, p0, [x1]
+; CHECK-BE-NEXT:    st1b { z1.b }, p0, [x1, #1, mul vl]
+; CHECK-BE-NEXT:    ret
+;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
@@ -52,6 +62,25 @@ define void @nxv16i8_max_range(ptr %ldptr, ptr %stptr) {
 ; CHECK-NEXT:    stp q0, q1, [x1, #1008]
 ; CHECK-NEXT:    ret
 ;
+; CHECK-BE-LABEL: nxv16i8_max_range:
+; CHECK-BE:       // %bb.0:
+; CHECK-BE-NEXT:    rdvl x8, #1
+; CHECK-BE-NEXT:    mov x9, #-1008 // =0xfffffffffffffc10
+; CHECK-BE-NEXT:    mov x10, #-1024 // =0xfffffffffffffc00
+; CHECK-BE-NEXT:    lsr x8, x8, #4
+; CHECK-BE-NEXT:    mov w11, #1008 // =0x3f0
+; CHECK-BE-NEXT:    mov w12, #1024 // =0x400
+; CHECK-BE-NEXT:    ptrue p0.b
+; CHECK-BE-NEXT:    mul x9, x8, x9
+; CHECK-BE-NEXT:    mul x10, x8, x10
+; CHECK-BE-NEXT:    mul x11, x8, x11
+; CHECK-BE-NEXT:    ld1b { z1.b }, p0/z, [x0, x9]
+; CHECK-BE-NEXT:    mul x8, x8, x12
+; CHECK-BE-NEXT:    ld1b { z0.b }, p0/z, [x0, x10]
+; CHECK-BE-NEXT:    st1b { z0.b }, p0, [x1, x11]
+; CHECK-BE-NEXT:    st1b { z1.b }, p0, [x1, x8]
+; CHECK-BE-NEXT:    ret
+;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_max_range:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0, #-64, mul vl]
@@ -98,6 +127,25 @@ define void @nxv16i8_outside_range(ptr %ldptr, ptr %stptr) {
 ; CHECK-NEXT:    str z1, [x1, #65, mul vl]
 ; CHECK-NEXT:    ret
 ;
+; CHECK-BE-LABEL: nxv16i8_outside_range:
+; CHECK-BE:       // %bb.0:
+; CHECK-BE-NEXT:    rdvl x8, #1
+; CHECK-BE-NEXT:    mov x9, #-1040 // =0xfffffffffffffbf0
+; CHECK-BE-NEXT:    mov x10, #-1024 // =0xfffffffffffffc00
+; CHECK-BE-NEXT:    lsr x8, x8, #4
+; CHECK-BE-NEXT:    mov w11, #1024 // =0x400
+; CHECK-BE-NEXT:    mov w12, #1040 // =0x410
+; CHECK-BE-NEXT:    ptrue p0.b
+; CHECK-BE-NEXT:    mul x9, x8, x9
+; CHECK-BE-NEXT:    mul x10, x8, x10
+; CHECK-BE-NEXT:    mul x11, x8, x11
+; CHECK-BE-NEXT:    ld1b { z0.b }, p0/z, [x0, x9]
+; CHECK-BE-NEXT:    mul x8, x8, x12
+; CHECK-BE-NEXT:    ld1b { z1.b }, p0/z, [x0, x10]
+; CHECK-BE-NEXT:    st1b { z0.b }, p0, [x1, x11]
+; CHECK-BE-NEXT:    st1b { z1.b }, p0, [x1, x8]
+; CHECK-BE-NEXT:    ret
+;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_outside_range:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0, #-65, mul vl]
@@ -146,6 +194,15 @@ define void @nxv16i8_2vl_stride(ptr %ldptr, ptr %stptr) {
 ; CHECK-NEXT:    str z1, [x1, #2, mul vl]
 ; CHECK-NEXT:    ret
 ;
+; CHECK-BE-LABEL: nxv16i8_2vl_stride:
+; CHECK-BE:       // %bb.0:
+; CHECK-BE-NEXT:    ptrue p0.b
+; CHECK-BE-NEXT:    ld1b { z0.b }, p0/z, [x0]
+; CHECK-BE-NEXT:    ld1b { z1.b }, p0/z, [x0, #2, mul vl]
+; CHECK-BE-NEXT:    st1b { z0.b }, p0, [x1]
+; CHECK-BE-NEXT:    st1b { z1.b }, p0, [x1, #2, mul vl]
+; CHECK-BE-NEXT:    ret
+;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv16i8_2vl_stride:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldr z0, [x0]
@@ -187,6 +244,15 @@ define void @nxv2f64_32b_aligned(ptr %ldptr, ptr %stptr) {
 ; CHECK-NEXT:    stp q0, q1, [x1]
 ; CHECK-NEXT:    ret
 ;
+; CHECK-BE-LABEL: nxv2f64_32b_aligned:
+; CHECK-BE:       // %bb.0:
+; CHECK-BE-NEXT:    ptrue p0.d
+; CHECK-BE-NEXT:    ld1d { z0.d }, p0/z, [x0]
+; CHECK-BE-NEXT:    ld1d { z1.d }, p0/z, [x0, #1, mul vl]
+; CHECK-BE-NEXT:    st1d { z0.d }, p0, [x1]
+; CHECK-BE-NEXT:    st1d { z1.d }, p0, [x1, #1, mul vl]
+; CHECK-BE-NEXT:    ret
+;
 ; CHECK-LDPALIGNEDONLY-LABEL: nxv2f64_32b_aligned:
 ; CHECK-LDPALIGNEDONLY:       // %bb.0:
 ; CHECK-LDPALIGNEDONLY-NEXT:    ldp q0, q1, [x0]

>From 5bb7624012c57de3ce43824260946bbba8b5d7a5 Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Mon, 7 Apr 2025 09:27:02 -0700
Subject: [PATCH 4/6] Remove DisableSVEFillSpillPairing

---
 llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp    | 8 +-------
 llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll | 1 -
 2 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index b1240b3709c17..aa6a31d79677a 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -87,11 +87,6 @@ static cl::opt<unsigned> LdStConstLimit("aarch64-load-store-const-scan-limit",
 static cl::opt<bool> EnableRenaming("aarch64-load-store-renaming",
                                     cl::init(true), cl::Hidden);
 
-// Disable SVE fill/spill pairing for VLS 128.
-static cl::opt<bool>
-    DisableSVEFillSpillPairing("aarch64-disable-sve-fill-spill-pairing",
-                               cl::init(false), cl::Hidden);
-
 #define AARCH64_LOAD_STORE_OPT_NAME "AArch64 load / store optimization pass"
 
 namespace {
@@ -2816,8 +2811,7 @@ bool AArch64LoadStoreOpt::tryToMergeIndexLdSt(MachineBasicBlock::iterator &MBBI,
 bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
                                         bool EnableNarrowZeroStOpt) {
   AArch64FunctionInfo &AFI = *MBB.getParent()->getInfo<AArch64FunctionInfo>();
-  bool const CanPairFillSpill = !DisableSVEFillSpillPairing &&
-                                Subtarget->isLittleEndian() &&
+  bool const CanPairFillSpill = Subtarget->isLittleEndian() &&
                                 Subtarget->isSVEorStreamingSVEAvailable() &&
                                 Subtarget->getSVEVectorSizeInBits() == 128;
 
diff --git a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
index a06af29fbc5ee..503ead4eba2db 100644
--- a/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
+++ b/llvm/test/CodeGen/AArch64/aarch64-sve-fill-spill-pair.ll
@@ -5,7 +5,6 @@
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve,stp-aligned-only -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 < %s | FileCheck %s --check-prefixes=CHECK-STPALIGNEDONLY
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve < %s | FileCheck %s --check-prefixes=CHECK-OFF
 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=256 -aarch64-sve-vector-bits-max=256 < %s | FileCheck %s --check-prefixes=CHECK-OFF
-; RUN: llc -verify-machineinstrs -mtriple=aarch64-linux-gnu -mattr=+sve -aarch64-sve-vector-bits-min=128 -aarch64-sve-vector-bits-max=128 -aarch64-disable-sve-fill-spill-pairing=1 < %s | FileCheck %s --check-prefixes=CHECK-OFF
 
 define void @nxv16i8(ptr %ldptr, ptr %stptr) {
 ; CHECK-LABEL: nxv16i8:

>From fce728cd8d02d4e0a9cfdc44a9179523717e0c3e Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Mon, 7 Apr 2025 10:02:33 -0700
Subject: [PATCH 5/6] Remove isPairableFillSpillInst

---
 llvm/lib/Target/AArch64/AArch64InstrInfo.cpp  | 14 +++++++++++++
 .../AArch64/AArch64LoadStoreOptimizer.cpp     | 21 +++++--------------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 9f8082b64ab18..5c1b8bbe29d63 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -2759,6 +2759,9 @@ 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;
   }
 }
@@ -2911,6 +2914,17 @@ 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:
+    return Subtarget.isLittleEndian() &&
+           Subtarget.getSVEVectorSizeInBits() == 128;
+  }
+
   // Check if this load/store has a hint to avoid pair formation.
   // MachineMemOperands hints are set by the AArch64StorePairSuppress pass.
   if (isLdStPairSuppressed(MI))
diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index aa6a31d79677a..1f4881be54871 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -843,12 +843,6 @@ static bool isMergeableIndexLdSt(MachineInstr &MI, int &Scale) {
   }
 }
 
-// Return true if MI is an SVE fill/spill instruction.
-static bool isPairableFillSpillInst(const MachineInstr &MI) {
-  auto const Opc = MI.getOpcode();
-  return Opc == AArch64::LDR_ZXI || Opc == AArch64::STR_ZXI;
-}
-
 static bool isRewritableImplicitDef(unsigned Opc) {
   switch (Opc) {
   default:
@@ -1854,9 +1848,6 @@ AArch64LoadStoreOpt::findMatchingInsn(MachineBasicBlock::iterator I,
 
   Flags.clearRenameReg();
 
-  if (isPairableFillSpillInst(FirstMI))
-    Flags.setSVEFillSpillPair();
-
   // Track which register units have been modified and used between the first
   // insn (inclusive) and the second insn.
   ModifiedRegUnits.clear();
@@ -2675,6 +2666,11 @@ bool AArch64LoadStoreOpt::tryToPairLdStInst(MachineBasicBlock::iterator &MBBI) {
     MachineMemOperand *MemOp =
         MI.memoperands_empty() ? nullptr : MI.memoperands().front();
 
+    // If we are pairing SVE fill/spill, set the appropriate flag.
+    unsigned Opcode = MI.getOpcode();
+    if (Opcode == AArch64::LDR_ZXI || Opcode == AArch64::STR_ZXI)
+      Flags.setSVEFillSpillPair();
+
     // If a load/store arrives and ldp/stp-aligned-only feature is opted, check
     // that the alignment of the source pointer is at least double the alignment
     // of the type.
@@ -2811,10 +2807,6 @@ bool AArch64LoadStoreOpt::tryToMergeIndexLdSt(MachineBasicBlock::iterator &MBBI,
 bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
                                         bool EnableNarrowZeroStOpt) {
   AArch64FunctionInfo &AFI = *MBB.getParent()->getInfo<AArch64FunctionInfo>();
-  bool const CanPairFillSpill = Subtarget->isLittleEndian() &&
-                                Subtarget->isSVEorStreamingSVEAvailable() &&
-                                Subtarget->getSVEVectorSizeInBits() == 128;
-
   bool Modified = false;
   // Four tranformations to do here:
   // 1) Find loads that directly read from stores and promote them by
@@ -2879,9 +2871,6 @@ bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
     updateDefinedRegisters(*MBBI, DefinedInBB, TRI);
     if (TII->isPairableLdStInst(*MBBI) && tryToPairLdStInst(MBBI))
       Modified = true;
-    else if (CanPairFillSpill && isPairableFillSpillInst(*MBBI) &&
-             tryToPairLdStInst(MBBI))
-      Modified = true;
     else
       ++MBBI;
   }

>From e5db0d376896510b577161aa1560b0454d52d281 Mon Sep 17 00:00:00 2001
From: Ricardo Jesus <rjj at nvidia.com>
Date: Tue, 8 Apr 2025 01:09:26 -0700
Subject: [PATCH 6/6] Remove SVEFillSpillPair flag

---
 .../Target/AArch64/AArch64LoadStoreOptimizer.cpp  | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index 1f4881be54871..f6b1a8ed162cc 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -97,9 +97,6 @@ using LdStPairFlags = struct LdStPairFlags {
   // a pair-wise insn, and false if the reverse is true.
   bool MergeForward = false;
 
-  // Set to true when pairing SVE fill/spill instructions.
-  bool SVEFillSpillPair = false;
-
   // SExtIdx gives the index of the result of the load pair that must be
   // extended. The value of SExtIdx assumes that the paired load produces the
   // value in this order: (I, returned iterator), i.e., -1 means no value has
@@ -116,9 +113,6 @@ using LdStPairFlags = struct LdStPairFlags {
   void setMergeForward(bool V = true) { MergeForward = V; }
   bool getMergeForward() const { return MergeForward; }
 
-  void setSVEFillSpillPair(bool V = true) { SVEFillSpillPair = V; }
-  bool getSVEFillSpillPair() const { return SVEFillSpillPair; }
-
   void setSExtIdx(int V) { SExtIdx = V; }
   int getSExtIdx() const { return SExtIdx; }
 
@@ -1237,8 +1231,8 @@ AArch64LoadStoreOpt::mergePairedInsns(MachineBasicBlock::iterator I,
     (void)MIBSXTW;
     LLVM_DEBUG(dbgs() << "  Extend operand:\n    ");
     LLVM_DEBUG(((MachineInstr *)MIBSXTW)->print(dbgs()));
-  } else if (Flags.getSVEFillSpillPair()) {
-    // We are combining SVE fill/spill to LDP/STP, so we need to get the Q
+  } 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);
@@ -2666,11 +2660,6 @@ bool AArch64LoadStoreOpt::tryToPairLdStInst(MachineBasicBlock::iterator &MBBI) {
     MachineMemOperand *MemOp =
         MI.memoperands_empty() ? nullptr : MI.memoperands().front();
 
-    // If we are pairing SVE fill/spill, set the appropriate flag.
-    unsigned Opcode = MI.getOpcode();
-    if (Opcode == AArch64::LDR_ZXI || Opcode == AArch64::STR_ZXI)
-      Flags.setSVEFillSpillPair();
-
     // If a load/store arrives and ldp/stp-aligned-only feature is opted, check
     // that the alignment of the source pointer is at least double the alignment
     // of the type.



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