[llvm-branch-commits] [llvm] PR for llvm/llvm-project#79756 (PR #79814)
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Mon Jan 29 04:07:04 PST 2024
https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/79814
resolves llvm/llvm-project#79756
>From 2ca45150c7984eea123409e6a7d25b2c7606ef5c Mon Sep 17 00:00:00 2001
From: David Green <david.green at arm.com>
Date: Sun, 28 Jan 2024 17:01:21 +0000
Subject: [PATCH] Revert "[AArch64] merge index address with large offset into
base address"
This reverts commit 32878c2065c8005b3ea30c79e16dfd7eed55d645 due to #79756 and #76202.
(cherry picked from commit 915c3d9e5a2d1314afe64cd6116a3b6c9809ec90)
---
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp | 10 -
llvm/lib/Target/AArch64/AArch64InstrInfo.h | 3 -
.../AArch64/AArch64LoadStoreOptimizer.cpp | 229 ------------------
llvm/test/CodeGen/AArch64/arm64-addrmode.ll | 15 +-
.../AArch64/large-offset-ldr-merge.mir | 5 +-
5 files changed, 12 insertions(+), 250 deletions(-)
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 2e8d8c63d6bec2..13e9d9725cc2ed 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -4098,16 +4098,6 @@ AArch64InstrInfo::getLdStOffsetOp(const MachineInstr &MI) {
return MI.getOperand(Idx);
}
-const MachineOperand &
-AArch64InstrInfo::getLdStAmountOp(const MachineInstr &MI) {
- switch (MI.getOpcode()) {
- default:
- llvm_unreachable("Unexpected opcode");
- case AArch64::LDRBBroX:
- return MI.getOperand(4);
- }
-}
-
static const TargetRegisterClass *getRegClass(const MachineInstr &MI,
Register Reg) {
if (MI.getParent() == nullptr)
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.h b/llvm/lib/Target/AArch64/AArch64InstrInfo.h
index db24a19fe5f8e3..6526f6740747ab 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.h
@@ -111,9 +111,6 @@ class AArch64InstrInfo final : public AArch64GenInstrInfo {
/// Returns the immediate offset operator of a load/store.
static const MachineOperand &getLdStOffsetOp(const MachineInstr &MI);
- /// Returns the shift amount operator of a load/store.
- static const MachineOperand &getLdStAmountOp(const MachineInstr &MI);
-
/// Returns whether the instruction is FP or NEON.
static bool isFpOrNEON(const MachineInstr &MI);
diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index e90b8a8ca7acee..926a89466255ca 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -62,8 +62,6 @@ STATISTIC(NumUnscaledPairCreated,
"Number of load/store from unscaled generated");
STATISTIC(NumZeroStoresPromoted, "Number of narrow zero stores promoted");
STATISTIC(NumLoadsFromStoresPromoted, "Number of loads from stores promoted");
-STATISTIC(NumConstOffsetFolded,
- "Number of const offset of index address folded");
DEBUG_COUNTER(RegRenamingCounter, DEBUG_TYPE "-reg-renaming",
"Controls which pairs are considered for renaming");
@@ -77,11 +75,6 @@ static cl::opt<unsigned> LdStLimit("aarch64-load-store-scan-limit",
static cl::opt<unsigned> UpdateLimit("aarch64-update-scan-limit", cl::init(100),
cl::Hidden);
-// The LdStConstLimit limits how far we search for const offset instructions
-// when we form index address load/store instructions.
-static cl::opt<unsigned> LdStConstLimit("aarch64-load-store-const-scan-limit",
- cl::init(10), cl::Hidden);
-
// Enable register renaming to find additional store pairing opportunities.
static cl::opt<bool> EnableRenaming("aarch64-load-store-renaming",
cl::init(true), cl::Hidden);
@@ -178,13 +171,6 @@ struct AArch64LoadStoreOpt : public MachineFunctionPass {
findMatchingUpdateInsnForward(MachineBasicBlock::iterator I,
int UnscaledOffset, unsigned Limit);
- // Scan the instruction list to find a register assigned with a const
- // value that can be combined with the current instruction (a load or store)
- // using base addressing with writeback. Scan forwards.
- MachineBasicBlock::iterator
- findMatchingConstOffsetBackward(MachineBasicBlock::iterator I, unsigned Limit,
- unsigned &Offset);
-
// Scan the instruction list to find a base register update that can
// be combined with the current instruction (a load or store) using
// pre or post indexed addressing with writeback. Scan backwards.
@@ -196,19 +182,11 @@ struct AArch64LoadStoreOpt : public MachineFunctionPass {
bool isMatchingUpdateInsn(MachineInstr &MemMI, MachineInstr &MI,
unsigned BaseReg, int Offset);
- bool isMatchingMovConstInsn(MachineInstr &MemMI, MachineInstr &MI,
- unsigned IndexReg, unsigned &Offset);
-
// Merge a pre- or post-index base register update into a ld/st instruction.
MachineBasicBlock::iterator
mergeUpdateInsn(MachineBasicBlock::iterator I,
MachineBasicBlock::iterator Update, bool IsPreIdx);
- MachineBasicBlock::iterator
- mergeConstOffsetInsn(MachineBasicBlock::iterator I,
- MachineBasicBlock::iterator Update, unsigned Offset,
- int Scale);
-
// Find and merge zero store instructions.
bool tryToMergeZeroStInst(MachineBasicBlock::iterator &MBBI);
@@ -221,9 +199,6 @@ struct AArch64LoadStoreOpt : public MachineFunctionPass {
// Find and merge a base register updates before or after a ld/st instruction.
bool tryToMergeLdStUpdate(MachineBasicBlock::iterator &MBBI);
- // Find and merge a index ldr/st instructions into a base ld/st instruction.
- bool tryToMergeIndexLdSt(MachineBasicBlock::iterator &MBBI, int Scale);
-
bool optimizeBlock(MachineBasicBlock &MBB, bool EnableNarrowZeroStOpt);
bool runOnMachineFunction(MachineFunction &Fn) override;
@@ -506,16 +481,6 @@ static unsigned getPreIndexedOpcode(unsigned Opc) {
}
}
-static unsigned getBaseAddressOpcode(unsigned Opc) {
- // TODO: Add more index address loads/stores.
- switch (Opc) {
- default:
- llvm_unreachable("Opcode has no base address equivalent!");
- case AArch64::LDRBBroX:
- return AArch64::LDRBBui;
- }
-}
-
static unsigned getPostIndexedOpcode(unsigned Opc) {
switch (Opc) {
default:
@@ -757,20 +722,6 @@ static bool isMergeableLdStUpdate(MachineInstr &MI) {
}
}
-// Make sure this is a reg+reg Ld/St
-static bool isMergeableIndexLdSt(MachineInstr &MI, int &Scale) {
- unsigned Opc = MI.getOpcode();
- switch (Opc) {
- default:
- return false;
- // Scaled instructions.
- // TODO: Add more index address loads/stores.
- case AArch64::LDRBBroX:
- Scale = 1;
- return true;
- }
-}
-
static bool isRewritableImplicitDef(unsigned Opc) {
switch (Opc) {
default:
@@ -2097,63 +2048,6 @@ AArch64LoadStoreOpt::mergeUpdateInsn(MachineBasicBlock::iterator I,
return NextI;
}
-MachineBasicBlock::iterator
-AArch64LoadStoreOpt::mergeConstOffsetInsn(MachineBasicBlock::iterator I,
- MachineBasicBlock::iterator Update,
- unsigned Offset, int Scale) {
- assert((Update->getOpcode() == AArch64::MOVKWi) &&
- "Unexpected const mov instruction to merge!");
- MachineBasicBlock::iterator E = I->getParent()->end();
- MachineBasicBlock::iterator NextI = next_nodbg(I, E);
- MachineBasicBlock::iterator PrevI = prev_nodbg(Update, E);
- MachineInstr &MemMI = *I;
- unsigned Mask = (1 << 12) * Scale - 1;
- unsigned Low = Offset & Mask;
- unsigned High = Offset - Low;
- Register BaseReg = AArch64InstrInfo::getLdStBaseOp(MemMI).getReg();
- Register IndexReg = AArch64InstrInfo::getLdStOffsetOp(MemMI).getReg();
- MachineInstrBuilder AddMIB, MemMIB;
-
- // Add IndexReg, BaseReg, High (the BaseReg may be SP)
- AddMIB =
- BuildMI(*I->getParent(), I, I->getDebugLoc(), TII->get(AArch64::ADDXri))
- .addDef(IndexReg)
- .addUse(BaseReg)
- .addImm(High >> 12) // shifted value
- .addImm(12); // shift 12
- (void)AddMIB;
- // Ld/St DestReg, IndexReg, Imm12
- unsigned NewOpc = getBaseAddressOpcode(I->getOpcode());
- MemMIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), TII->get(NewOpc))
- .add(getLdStRegOp(MemMI))
- .add(AArch64InstrInfo::getLdStOffsetOp(MemMI))
- .addImm(Low / Scale)
- .setMemRefs(I->memoperands())
- .setMIFlags(I->mergeFlagsWith(*Update));
- (void)MemMIB;
-
- ++NumConstOffsetFolded;
- LLVM_DEBUG(dbgs() << "Creating base address load/store.\n");
- LLVM_DEBUG(dbgs() << " Replacing instructions:\n ");
- LLVM_DEBUG(PrevI->print(dbgs()));
- LLVM_DEBUG(dbgs() << " ");
- LLVM_DEBUG(Update->print(dbgs()));
- LLVM_DEBUG(dbgs() << " ");
- LLVM_DEBUG(I->print(dbgs()));
- LLVM_DEBUG(dbgs() << " with instruction:\n ");
- LLVM_DEBUG(((MachineInstr *)AddMIB)->print(dbgs()));
- LLVM_DEBUG(dbgs() << " ");
- LLVM_DEBUG(((MachineInstr *)MemMIB)->print(dbgs()));
- LLVM_DEBUG(dbgs() << "\n");
-
- // Erase the old instructions for the block.
- I->eraseFromParent();
- PrevI->eraseFromParent();
- Update->eraseFromParent();
-
- return NextI;
-}
-
bool AArch64LoadStoreOpt::isMatchingUpdateInsn(MachineInstr &MemMI,
MachineInstr &MI,
unsigned BaseReg, int Offset) {
@@ -2201,31 +2095,6 @@ bool AArch64LoadStoreOpt::isMatchingUpdateInsn(MachineInstr &MemMI,
return false;
}
-bool AArch64LoadStoreOpt::isMatchingMovConstInsn(MachineInstr &MemMI,
- MachineInstr &MI,
- unsigned IndexReg,
- unsigned &Offset) {
- // The update instruction source and destination register must be the
- // same as the load/store index register.
- if (MI.getOpcode() == AArch64::MOVKWi &&
- TRI->isSuperOrSubRegisterEq(IndexReg, MI.getOperand(1).getReg())) {
-
- // movz + movk hold a large offset of a Ld/St instruction.
- MachineBasicBlock::iterator B = MI.getParent()->begin();
- MachineBasicBlock::iterator MBBI = &MI;
- MBBI = prev_nodbg(MBBI, B);
- MachineInstr &MovzMI = *MBBI;
- if (MovzMI.getOpcode() == AArch64::MOVZWi) {
- unsigned Low = MovzMI.getOperand(1).getImm();
- unsigned High = MI.getOperand(2).getImm() << MI.getOperand(3).getImm();
- Offset = High + Low;
- // 12-bit optionally shifted immediates are legal for adds.
- return Offset >> 24 == 0;
- }
- }
- return false;
-}
-
MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnForward(
MachineBasicBlock::iterator I, int UnscaledOffset, unsigned Limit) {
MachineBasicBlock::iterator E = I->getParent()->end();
@@ -2381,60 +2250,6 @@ MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnBackward(
return E;
}
-MachineBasicBlock::iterator
-AArch64LoadStoreOpt::findMatchingConstOffsetBackward(
- MachineBasicBlock::iterator I, unsigned Limit, unsigned &Offset) {
- MachineBasicBlock::iterator B = I->getParent()->begin();
- MachineBasicBlock::iterator E = I->getParent()->end();
- MachineInstr &MemMI = *I;
- MachineBasicBlock::iterator MBBI = I;
-
- // If the load is the first instruction in the block, there's obviously
- // not any matching load or store.
- if (MBBI == B)
- return E;
-
- // Make sure the IndexReg is killed and the shift amount is zero.
- // TODO: Relex this restriction to extend, simplify processing now.
- if (!AArch64InstrInfo::getLdStOffsetOp(MemMI).isKill() ||
- !AArch64InstrInfo::getLdStAmountOp(MemMI).isImm() ||
- (AArch64InstrInfo::getLdStAmountOp(MemMI).getImm() != 0))
- return E;
-
- Register IndexReg = AArch64InstrInfo::getLdStOffsetOp(MemMI).getReg();
-
- // Track which register units have been modified and used between the first
- // insn (inclusive) and the second insn.
- ModifiedRegUnits.clear();
- UsedRegUnits.clear();
- unsigned Count = 0;
- do {
- MBBI = prev_nodbg(MBBI, B);
- MachineInstr &MI = *MBBI;
-
- // Don't count transient instructions towards the search limit since there
- // may be different numbers of them if e.g. debug information is present.
- if (!MI.isTransient())
- ++Count;
-
- // If we found a match, return it.
- if (isMatchingMovConstInsn(*I, MI, IndexReg, Offset)) {
- return MBBI;
- }
-
- // Update the status of what the instruction clobbered and used.
- LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits, TRI);
-
- // Otherwise, if the index register is used or modified, we have no match,
- // so return early.
- if (!ModifiedRegUnits.available(IndexReg) ||
- !UsedRegUnits.available(IndexReg))
- return E;
-
- } while (MBBI != B && Count < Limit);
- return E;
-}
-
bool AArch64LoadStoreOpt::tryToPromoteLoadFromStore(
MachineBasicBlock::iterator &MBBI) {
MachineInstr &MI = *MBBI;
@@ -2619,34 +2434,6 @@ bool AArch64LoadStoreOpt::tryToMergeLdStUpdate
return false;
}
-bool AArch64LoadStoreOpt::tryToMergeIndexLdSt(MachineBasicBlock::iterator &MBBI,
- int Scale) {
- MachineInstr &MI = *MBBI;
- MachineBasicBlock::iterator E = MI.getParent()->end();
- MachineBasicBlock::iterator Update;
-
- // Don't know how to handle unscaled pre/post-index versions below, so bail.
- if (TII->hasUnscaledLdStOffset(MI.getOpcode()))
- return false;
-
- // Look back to try to find a const offset for index LdSt instruction. For
- // example,
- // mov x8, #LargeImm ; = a * (1<<12) + imm12
- // ldr x1, [x0, x8]
- // merged into:
- // add x8, x0, a * (1<<12)
- // ldr x1, [x8, imm12]
- unsigned Offset;
- Update = findMatchingConstOffsetBackward(MBBI, LdStConstLimit, Offset);
- if (Update != E && (Offset & (Scale - 1)) == 0) {
- // Merge the imm12 into the ld/st.
- MBBI = mergeConstOffsetInsn(MBBI, Update, Offset, Scale);
- return true;
- }
-
- return false;
-}
-
bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
bool EnableNarrowZeroStOpt) {
@@ -2725,22 +2512,6 @@ bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
++MBBI;
}
- // 5) Find a register assigned with a const value that can be combined with
- // into the load or store. e.g.,
- // mov x8, #LargeImm ; = a * (1<<12) + imm12
- // ldr x1, [x0, x8]
- // ; becomes
- // add x8, x0, a * (1<<12)
- // ldr x1, [x8, imm12]
- for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
- MBBI != E;) {
- int Scale;
- if (isMergeableIndexLdSt(*MBBI, Scale) && tryToMergeIndexLdSt(MBBI, Scale))
- Modified = true;
- else
- ++MBBI;
- }
-
return Modified;
}
diff --git a/llvm/test/CodeGen/AArch64/arm64-addrmode.ll b/llvm/test/CodeGen/AArch64/arm64-addrmode.ll
index 2181eaaee7db68..d39029163a47aa 100644
--- a/llvm/test/CodeGen/AArch64/arm64-addrmode.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-addrmode.ll
@@ -214,8 +214,9 @@ define void @t17(i64 %a) {
define i8 @LdOffset_i8(ptr %a) {
; CHECK-LABEL: LdOffset_i8:
; CHECK: // %bb.0:
-; CHECK-NEXT: add x8, x0, #253, lsl #12 // =1036288
-; CHECK-NEXT: ldrb w0, [x8, #3704]
+; CHECK-NEXT: mov w8, #56952 // =0xde78
+; CHECK-NEXT: movk w8, #15, lsl #16
+; CHECK-NEXT: ldrb w0, [x0, x8]
; CHECK-NEXT: ret
%arrayidx = getelementptr inbounds i8, ptr %a, i64 1039992
%val = load i8, ptr %arrayidx, align 1
@@ -226,8 +227,9 @@ define i8 @LdOffset_i8(ptr %a) {
define i32 @LdOffset_i8_zext32(ptr %a) {
; CHECK-LABEL: LdOffset_i8_zext32:
; CHECK: // %bb.0:
-; CHECK-NEXT: add x8, x0, #253, lsl #12 // =1036288
-; CHECK-NEXT: ldrb w0, [x8, #3704]
+; CHECK-NEXT: mov w8, #56952 // =0xde78
+; CHECK-NEXT: movk w8, #15, lsl #16
+; CHECK-NEXT: ldrb w0, [x0, x8]
; CHECK-NEXT: ret
%arrayidx = getelementptr inbounds i8, ptr %a, i64 1039992
%val = load i8, ptr %arrayidx, align 1
@@ -253,8 +255,9 @@ define i32 @LdOffset_i8_sext32(ptr %a) {
define i64 @LdOffset_i8_zext64(ptr %a) {
; CHECK-LABEL: LdOffset_i8_zext64:
; CHECK: // %bb.0:
-; CHECK-NEXT: add x8, x0, #253, lsl #12 // =1036288
-; CHECK-NEXT: ldrb w0, [x8, #3704]
+; CHECK-NEXT: mov w8, #56952 // =0xde78
+; CHECK-NEXT: movk w8, #15, lsl #16
+; CHECK-NEXT: ldrb w0, [x0, x8]
; CHECK-NEXT: ret
%arrayidx = getelementptr inbounds i8, ptr %a, i64 1039992
%val = load i8, ptr %arrayidx, align 1
diff --git a/llvm/test/CodeGen/AArch64/large-offset-ldr-merge.mir b/llvm/test/CodeGen/AArch64/large-offset-ldr-merge.mir
index 15b6700398ea08..488f1ffdb52f3b 100755
--- a/llvm/test/CodeGen/AArch64/large-offset-ldr-merge.mir
+++ b/llvm/test/CodeGen/AArch64/large-offset-ldr-merge.mir
@@ -14,8 +14,9 @@ body: |
; CHECK-LABEL: name: LdOffset
; CHECK: liveins: $x0
; CHECK-NEXT: {{ $}}
- ; CHECK-NEXT: $x8 = ADDXri $x0, 253, 12
- ; CHECK-NEXT: renamable $w0 = LDRBBui killed renamable $x8, 3704
+ ; CHECK-NEXT: renamable $w8 = MOVZWi 56952, 0
+ ; CHECK-NEXT: renamable $w8 = MOVKWi $w8, 15, 16, implicit-def $x8
+ ; CHECK-NEXT: renamable $w0 = LDRBBroX killed renamable $x0, killed renamable $x8, 0, 0
; CHECK-NEXT: RET undef $lr, implicit $w0
renamable $w8 = MOVZWi 56952, 0
renamable $w8 = MOVKWi $w8, 15, 16, implicit-def $x8
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