[AArch64] merge index address with large offset into base address #75343
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
@llvm/pr-subscribers-backend-aarch64 Author: Allen (vfdff) ChangesA case for this transformation, https://gcc.godbolt.org/z/nhYcWq1WE Fold Only LDRBBroX is supported for the first time. Full diff: https://github.com/llvm/llvm-project/pull/75343.diff 5 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 50cbd3672fbd0d..9214e54706f8ba 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -4089,6 +4089,11 @@ AArch64InstrInfo::getLdStOffsetOp(const MachineInstr &MI) {
return MI.getOperand(Idx);
}
+const MachineOperand &
+AArch64InstrInfo::getLdStAmountOp(const MachineInstr &MI) {
+ 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 e97ff0a9758d69..6ad1ef643a6897 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.h
@@ -111,6 +111,9 @@ 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 dc6d5b8950c34a..98dd9262463ecc 100644
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -62,6 +62,8 @@ 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");
@@ -75,6 +77,11 @@ 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);
@@ -171,6 +178,13 @@ 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.
@@ -182,11 +196,18 @@ 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);
+
// Find and merge zero store instructions.
bool tryToMergeZeroStInst(MachineBasicBlock::iterator &MBBI);
@@ -199,6 +220,9 @@ 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);
+
bool optimizeBlock(MachineBasicBlock &MBB, bool EnableNarrowZeroStOpt);
bool runOnMachineFunction(MachineFunction &Fn) override;
@@ -481,6 +505,16 @@ 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:
@@ -722,6 +756,19 @@ static bool isMergeableLdStUpdate(MachineInstr &MI) {
}
}
+// Make sure this is a reg+reg Ld/St
+static bool isMergeableIndexLdSt(MachineInstr &MI) {
+ unsigned Opc = MI.getOpcode();
+ switch (Opc) {
+ default:
+ return false;
+ // Scaled instructions.
+ // TODO: Add more index address loads/stores.
+ case AArch64::LDRBBroX:
+ return true;
+ }
+}
+
static bool isRewritableImplicitDef(unsigned Opc) {
switch (Opc) {
default:
@@ -2018,6 +2065,62 @@ AArch64LoadStoreOpt::mergeUpdateInsn(MachineBasicBlock::iterator I,
return NextI;
}
+MachineBasicBlock::iterator
+AArch64LoadStoreOpt::mergeConstOffsetInsn(MachineBasicBlock::iterator I,
+ MachineBasicBlock::iterator Update,
+ unsigned Offset) {
+ 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 Imm12 = Offset & 0x0fff;
+ unsigned High = Offset - Imm12;
+ 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(Imm12)
+ .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) {
@@ -2065,6 +2168,30 @@ 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;
+ return true;
+ }
+ }
+ return false;
+}
+
MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnForward(
MachineBasicBlock::iterator I, int UnscaledOffset, unsigned Limit) {
MachineBasicBlock::iterator E = I->getParent()->end();
@@ -2220,6 +2347,61 @@ 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 BaseReg = AArch64InstrInfo::getLdStBaseOp(MemMI).getReg();
+ 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;
@@ -2404,6 +2586,34 @@ bool AArch64LoadStoreOpt::tryToMergeLdStUpdate
return false;
}
+bool AArch64LoadStoreOpt::tryToMergeIndexLdSt(
+ MachineBasicBlock::iterator &MBBI) {
+ 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) {
+ // Merge the imm12 into the ld/st.
+ MBBI = mergeConstOffsetInsn(MBBI, Update, Offset);
+ return true;
+ }
+
+ return false;
+}
+
bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
bool EnableNarrowZeroStOpt) {
@@ -2482,6 +2692,21 @@ 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;) {
+ if (isMergeableIndexLdSt(*MBBI) && tryToMergeIndexLdSt(MBBI))
+ 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 3d4749a7b8e7df..e457fbdc34e3c4 100644
--- a/llvm/test/CodeGen/AArch64/arm64-addrmode.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-addrmode.ll
@@ -213,9 +213,8 @@ define void @t17(i64 %a) {
define i32 @LdOffset_i8(ptr %a) {
; CHECK-LABEL: LdOffset_i8:
; CHECK: // %bb.0:
-; CHECK-NEXT: mov w8, #56952 // =0xde78
-; CHECK-NEXT: movk w8, #15, lsl #16
-; CHECK-NEXT: ldrb w0, [x0, x8]
+; CHECK-NEXT: add x8, x0, #253, lsl #12 // =1036288
+; CHECK-NEXT: ldrb w0, [x8, #3704]
; 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
new file mode 100644
index 00000000000000..15b6700398ea08
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/large-offset-ldr-merge.mir
@@ -0,0 +1,47 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=aarch64 -run-pass aarch64-ldst-opt %s -o - | FileCheck %s
+
+
+---
+name: LdOffset
+tracksRegLiveness: true
+liveins:
+ - { reg: '$x0', virtual-reg: '' }
+body: |
+ bb.0.entry:
+ liveins: $x0
+
+ ; 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: RET undef $lr, implicit $w0
+ renamable $w8 = MOVZWi 56952, 0
+ renamable $w8 = MOVKWi $w8, 15, 16, implicit-def $x8
+ renamable $w0 = LDRBBroX killed renamable $x0, killed renamable $x8, 0, 0
+ RET undef $lr, implicit $w0
+...
+
+# Negative test: the IndexReg missing killed flags
+---
+name: LdOffset_missing_killed
+tracksRegLiveness: true
+liveins:
+ - { reg: '$x0', virtual-reg: '' }
+body: |
+ bb.0.entry:
+ liveins: $x0
+
+ ; CHECK-LABEL: name: LdOffset_missing_killed
+ ; CHECK: liveins: $x0
+ ; CHECK-NEXT: {{ $}}
+ ; 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, 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
+ renamable $w0 = LDRBBroX killed renamable $x0, renamable $x8, 0, 0
+ RET undef $lr, implicit $w0
+...
|
david-arm
reviewed
Dec 13, 2023
| @@ -4089,6 +4089,11 @@ AArch64InstrInfo::getLdStOffsetOp(const MachineInstr &MI) { | |||
| return MI.getOperand(Idx); | |||
| } | |||
|
|
|||
| const MachineOperand & | |||
| AArch64InstrInfo::getLdStAmountOp(const MachineInstr &MI) { | |||
| return MI.getOperand(4); | |||
There was a problem hiding this comment.
How do you know this is always going to be operand 4 without inspecting the opcode? For example, see the functions above.
There was a problem hiding this comment.
yes, it need extend with a switch case when we add more supported instrunction.
The first version I only supported the LDRBBroX , and it is operand 4.
I only add one instrunction in the first version to make sure if it is reasonable for the optimization direction itself.
If it is adopted, I will add other memory access instructions in the subsequent patch.
There was a problem hiding this comment.
OK, but my point is that if your patch lands another engineer may start using this function believing that it is complete. However, it might do the wrong thing if called for a different opcode. I think you need to explicitly add an error if the opcode is not what you expect so that it fails sensibly.
There was a problem hiding this comment.
Thanks for your idea, fixed with commit 01029d9
| // TODO: Add more index address loads/stores. | ||
| switch (Opc) { | ||
| default: | ||
| llvm_unreachable("Opcode has no base address equivalent!"); |
There was a problem hiding this comment.
At first glance this doesn't look right to me. Are there any checks to actually prevent us getting here with other opcodes? If not, then I think you may need to fill in the remaining opcodes in the switch statement, similar to getPostIndexedOpcode.
There was a problem hiding this comment.
yes, similar to above getLdStAmountOp，I only support LDRBBroX in the first version.
There was a problem hiding this comment.
I guess the point I'm trying to make here is that usually we add a llvm_unreachable because we actually expect the code to be unreachable. However, I can't see anything that prevents us hitting the default case. For example, I'd expect code to be written in this way:
void foo(MI) {
if (opcode == my_expected_opcode)
foo2(MI);
}
void foo2() {
switch (MI.getOpcode()) {
default:
llvm_unreachable("Unexpected opcode");
case my_expected_opcode:
do_something();
break;
}
}
My question was - do you have anything to explicitly prevent us from calling the function with an unexpected opcode?
There was a problem hiding this comment.
yes, the function isMergeableIndexLdSt called by AArch64LoadStoreOpt::optimizeBlock will check only the expected opcode will try this fold. (Now only support one opcode LDRBBroX )
vfdff
force-pushed
the
fix-547-point2-singleuse
branch
from
01029d9
to
b11ed55
Compare
|
support more load.x instruction, the list is refered to |
|
ping ? |
davemgreen
reviewed
Dec 19, 2023
|
|
||
| // 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() || |
There was a problem hiding this comment.
Is this essentially a one-use check on the MOV reg?
There was a problem hiding this comment.
yes, because we'll delete these old instructions when we match the folding at the end of function mergeConstOffsetInsn (I add a test LdOffset_missing_killed for it in file large-offset-ldr-merge.mir)
|
davemgreen
reviewed
Dec 20, 2023
| @@ -295,3 +459,27 @@ define i32 @LdOffset_i16_odd_offset(ptr nocapture noundef readonly %a) { | |||
| ret i32 %conv | |||
| } | |||
|
|
|||
| ; Already encoded with a signle mov MOVNWi | |||
| Scale = 2; | ||
| return true; | ||
| case AArch64::LDRWroX: | ||
| case AArch64::LDRSWroX: |
There was a problem hiding this comment.
Should there be LDRSroX too?
There was a problem hiding this comment.
Apply your comment, thanks
vfdff
force-pushed
the
fix-547-point2-singleuse
branch
from
cec5319
to
ad1f7d5
Compare
|
davemgreen
approved these changes
Dec 21, 2023
A case for this transformation, https://gcc.godbolt.org/z/nhYcWq1WE Fold mov w8, llvm#56952 movk w8, llvm#15, lsl llvm#16 ldrb w0, [x0, x8] into add x0, x0, 1036288 ldrb w0, [x0, 3704] Only LDRBBroX is supported for the first time. Fix llvm#71917
The list of load.x is refer to canFoldIntoAddrMode on D152828. Also support LDRSroX missed in canFoldIntoAddrMode
vfdff
force-pushed
the
fix-547-point2-singleuse
branch
from
ad1f7d5
to
f568763
Compare
|
heads-up : this is causing some tests crashing internally in google. Trying to come up with a reproducer. |
|
|
It looks like this is causing #79756 too. I hadn't realised that it was committed in separate commits and then only partially reverted. I'll remove the LDRBBroX part too to make sure we don't see problems on the llvm-19 branch. @vfdff there is a test case in #79756 that looks useful for figuring out at least one of the problems going on. |
|
@davemgreen Thanks very much for the case, I'll take a look at it. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
A case for this transformation, https://gcc.godbolt.org/z/nhYcWq1WE
Fold
into
Only LDRBBroX is supported for the first time.
Note: The AArch64DAGToDAGISel is difficult to check the loop invariant, which may bring in regression.
Fix #71917