Skip to content

[WebAssembly] Fix lowering of (truncating) stores from addrspace(1) globals #163136

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
+251 −4
Open

[WebAssembly] Fix lowering of (truncating) stores from addrspace(1) globals #163136

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
a18aabf
Pre-commit tests for fixing (truncating) stores to WASM globals
QuantumSegfault Oct 13, 2025
11ce64e
Fix (truncating) stores to WASM globals
QuantumSegfault Oct 13, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
88 changes: 84 additions & 4 deletions llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,12 @@ WebAssemblyTargetLowering::WebAssemblyTargetLowering(
}
}

setTruncStoreAction(MVT::i32, MVT::i8, Custom);
setTruncStoreAction(MVT::i32, MVT::i16, Custom);
setTruncStoreAction(MVT::i64, MVT::i8, Custom);
setTruncStoreAction(MVT::i64, MVT::i16, Custom);
setTruncStoreAction(MVT::i64, MVT::i32, Custom);

setOperationAction(ISD::GlobalAddress, MVTPtr, Custom);
setOperationAction(ISD::GlobalTLSAddress, MVTPtr, Custom);
setOperationAction(ISD::ExternalSymbol, MVTPtr, Custom);
Expand Down Expand Up @@ -1683,6 +1689,11 @@ static bool IsWebAssemblyGlobal(SDValue Op) {
if (const GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op))
return WebAssembly::isWasmVarAddressSpace(GA->getAddressSpace());

if (Op->getOpcode() == WebAssemblyISD::Wrapper)
if (const GlobalAddressSDNode *GA =
dyn_cast<GlobalAddressSDNode>(Op->getOperand(0)))
return WebAssembly::isWasmVarAddressSpace(GA->getAddressSpace());

return false;
}

Expand All @@ -1704,15 +1715,84 @@ SDValue WebAssemblyTargetLowering::LowerStore(SDValue Op,
const SDValue &Base = SN->getBasePtr();
const SDValue &Offset = SN->getOffset();

const EVT ValueType = Value.getValueType();
const EVT MemType = SN->getMemoryVT();

if (IsWebAssemblyGlobal(Base)) {
if (!Offset->isUndef())
report_fatal_error("unexpected offset when storing to webassembly global",
false);

SDVTList Tys = DAG.getVTList(MVT::Other);
SDValue Ops[] = {SN->getChain(), Value, Base};
return DAG.getMemIntrinsicNode(WebAssemblyISD::GLOBAL_SET, DL, Tys, Ops,
SN->getMemoryVT(), SN->getMemOperand());
if (!ValueType.isInteger()) {
SDVTList Tys = DAG.getVTList(MVT::Other);
SDValue Ops[] = {SN->getChain(), Value, Base};
return DAG.getMemIntrinsicNode(WebAssemblyISD::GLOBAL_SET, DL, Tys, Ops,
SN->getMemoryVT(), SN->getMemOperand());
}

EVT GT = MVT::INVALID_SIMPLE_VALUE_TYPE;

if (auto *GA = dyn_cast<GlobalAddressSDNode>(
Base->getOpcode() == WebAssemblyISD::Wrapper ? Base->getOperand(0)
: Base))
GT = EVT::getEVT(GA->getGlobal()->getValueType());

if (GT != MVT::i8 && GT != MVT::i16 && GT != MVT::i32 && GT != MVT::i64)
report_fatal_error("encountered unexpected global type for Base when "
"storing into webassembly global",
false);

EVT PromotedGT = getTypeToTransformTo(*DAG.getContext(), GT);

if (PromotedGT == ValueType && ValueType == MemType) {
SDVTList Tys = DAG.getVTList(MVT::Other);
SDValue Ops[] = {SN->getChain(), Value, Base};
return DAG.getMemIntrinsicNode(WebAssemblyISD::GLOBAL_SET, DL, Tys, Ops,
SN->getMemoryVT(), SN->getMemOperand());
}

SDValue ModifiedNewValue = Value;
if (MemType.bitsLT(ValueType)) {
APInt Mask = APInt::getLowBitsSet(ValueType.getFixedSizeInBits(),
MemType.getFixedSizeInBits());
ModifiedNewValue = DAG.getNode(ISD::AND, DL, ValueType, ModifiedNewValue,
DAG.getConstant(Mask, DL, ValueType));
}
if (ValueType != PromotedGT) {
ModifiedNewValue = DAG.getAnyExtOrTrunc(ModifiedNewValue, DL, PromotedGT);
}

SDValue Chain = SN->getChain();

SDValue CombinedValue = ModifiedNewValue;
if (GT.bitsGT(MemType)) {
MachineMemOperand &StoreMMO = *SN->getMemOperand();
MachineMemOperand *NewMMO = DAG.getMachineFunction().getMachineMemOperand(
StoreMMO.getPointerInfo(),
(StoreMMO.getFlags() & ~MachineMemOperand::Flags::MOStore) |
MachineMemOperand::Flags::MOLoad,
LLT(PromotedGT.getSimpleVT()), StoreMMO.getBaseAlign(),
StoreMMO.getAAInfo(), StoreMMO.getRanges(), StoreMMO.getSyncScopeID(),
StoreMMO.getSuccessOrdering(), StoreMMO.getFailureOrdering());

SDValue OrigValue = DAG.getLoad(PromotedGT, DL, Chain, Base, NewMMO);
Chain = OrigValue.getValue(1);
APInt Mask = APInt::getHighBitsSet(GT.getFixedSizeInBits(),
GT.getFixedSizeInBits() -
MemType.getFixedSizeInBits());
SDValue ModifiedOrigValue =
DAG.getNode(ISD::AND, DL, PromotedGT, OrigValue,
DAG.getConstant(Mask, DL, PromotedGT));
CombinedValue = DAG.getNode(ISD::OR, DL, PromotedGT, ModifiedNewValue,
ModifiedOrigValue);
}

MachineMemOperand *MMO = SN->getMemOperand();
MMO->setType(LLT(PromotedGT.getSimpleVT()));

SDValue NewStore = DAG.getStore(Chain, DL, CombinedValue, Base, MMO);

return NewStore;
}

if (std::optional<unsigned> Local = IsWebAssemblyLocal(Base, DAG)) {
Expand Down
167 changes: 167 additions & 0 deletions llvm/test/CodeGen/WebAssembly/lower-store-wasm-global.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,167 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc < %s | FileCheck %s

; Test various stores from WASM (address space 1) globals lower as intended

target triple = "wasm32-unknown-unknown"


@globalI8 = local_unnamed_addr addrspace(1) global i8 undef
@globalI32 = local_unnamed_addr addrspace(1) global i32 undef
@globalI64 = local_unnamed_addr addrspace(1) global i64 undef

define void @store_i8_to_i32(i8 %val) {
; CHECK-LABEL: store_i8_to_i32:
; CHECK: .functype store_i8_to_i32 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.const 255
; CHECK-NEXT: i32.and
; CHECK-NEXT: global.get globalI32
; CHECK-NEXT: i32.const -256
; CHECK-NEXT: i32.and
; CHECK-NEXT: i32.or
; CHECK-NEXT: global.set globalI32
; CHECK-NEXT: # fallthrough-return
store i8 %val, ptr addrspace(1) @globalI32
ret void
}

define void @store_i16_to_i32(i16 %val) {
; CHECK-LABEL: store_i16_to_i32:
; CHECK: .functype store_i16_to_i32 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.const 65535
; CHECK-NEXT: i32.and
; CHECK-NEXT: global.get globalI32
; CHECK-NEXT: i32.const -65536
; CHECK-NEXT: i32.and
; CHECK-NEXT: i32.or
; CHECK-NEXT: global.set globalI32
; CHECK-NEXT: # fallthrough-return
store i16 %val, ptr addrspace(1) @globalI32
ret void
}

define void @store_i32_to_i32(i32 %val) {
; CHECK-LABEL: store_i32_to_i32:
; CHECK: .functype store_i32_to_i32 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: global.set globalI32
; CHECK-NEXT: # fallthrough-return
store i32 %val, ptr addrspace(1) @globalI32
ret void
}

define void @store_i64_to_i32(i64 %val) {
; CHECK-LABEL: store_i64_to_i32:
; CHECK: .functype store_i64_to_i32 (i64) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.wrap_i64
; CHECK-NEXT: global.set globalI32
; CHECK-NEXT: # fallthrough-return
store i64 %val, ptr addrspace(1) @globalI32
ret void
}

define void @store_i8_to_i64(i8 %val) {
; CHECK-LABEL: store_i8_to_i64:
; CHECK: .functype store_i8_to_i64 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.const 255
; CHECK-NEXT: i32.and
; CHECK-NEXT: i64.extend_i32_u
; CHECK-NEXT: global.get globalI64
; CHECK-NEXT: i64.const -256
; CHECK-NEXT: i64.and
; CHECK-NEXT: i64.or
; CHECK-NEXT: global.set globalI64
; CHECK-NEXT: # fallthrough-return
store i8 %val, ptr addrspace(1) @globalI64
ret void
}

define void @store_i16_to_i64(i16 %val) {
; CHECK-LABEL: store_i16_to_i64:
; CHECK: .functype store_i16_to_i64 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.const 65535
; CHECK-NEXT: i32.and
; CHECK-NEXT: i64.extend_i32_u
; CHECK-NEXT: global.get globalI64
; CHECK-NEXT: i64.const -65536
; CHECK-NEXT: i64.and
; CHECK-NEXT: i64.or
; CHECK-NEXT: global.set globalI64
; CHECK-NEXT: # fallthrough-return
store i16 %val, ptr addrspace(1) @globalI64
ret void
}

define void @store_i32_to_i64(i32 %val) {
; CHECK-LABEL: store_i32_to_i64:
; CHECK: .functype store_i32_to_i64 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i64.extend_i32_u
; CHECK-NEXT: global.get globalI64
; CHECK-NEXT: i64.const -4294967296
; CHECK-NEXT: i64.and
; CHECK-NEXT: i64.or
; CHECK-NEXT: global.set globalI64
; CHECK-NEXT: # fallthrough-return
store i32 %val, ptr addrspace(1) @globalI64
ret void
}

define void @store_i64_to_i64(i64 %val) {
; CHECK-LABEL: store_i64_to_i64:
; CHECK: .functype store_i64_to_i64 (i64) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: global.set globalI64
; CHECK-NEXT: # fallthrough-return
store i64 %val, ptr addrspace(1) @globalI64
ret void
}

define void @store_i8_to_i8(i8 %val) {
; CHECK-LABEL: store_i8_to_i8:
; CHECK: .functype store_i8_to_i8 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.const 255
; CHECK-NEXT: i32.and
; CHECK-NEXT: global.set globalI8
; CHECK-NEXT: # fallthrough-return
store i8 %val, ptr addrspace(1) @globalI8
ret void
}

define void @store_i32_to_i8(i32 %val) {
; CHECK-LABEL: store_i32_to_i8:
; CHECK: .functype store_i32_to_i8 (i32) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: global.set globalI8
; CHECK-NEXT: # fallthrough-return
store i32 %val, ptr addrspace(1) @globalI8
ret void
}

define void @store_i64_to_i8(i64 %val) {
; CHECK-LABEL: store_i64_to_i8:
; CHECK: .functype store_i64_to_i8 (i64) -> ()
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: local.get 0
; CHECK-NEXT: i32.wrap_i64
; CHECK-NEXT: global.set globalI8
; CHECK-NEXT: # fallthrough-return
store i64 %val, ptr addrspace(1) @globalI8
ret void
}