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Implement header union invalidation in the BMv2 back end. #4982

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Implement header union invalidation in the BMv2 back end. #4982

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4ea69b5
Set other headers also invalid when calling setInvalid on a union hea…
fruffy Aug 5, 2024
17df75b
Add an option to copy structures to skip expanding header unions.
fruffy Aug 7, 2024
afcadec
Implement header union invaidation in the BMv2 back end.
fruffy Aug 5, 2024
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28 changes: 28 additions & 0 deletions backends/bmv2/common/action.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,29 @@ cstring ActionConverter::jsonAssignment(const IR::Type *type) {
return "assign"_cs;
}

namespace {
/// Invalidates all other headers in a header union except the provided source header.
/// Has no effect if the parent structure is not a header union.
void invalidateOtherHeaderUnionHeaders(const IR::Member *sourceHeader,
const ConversionContext &ctxt, Util::JsonArray *result,
const IR::StatOrDecl *sourceStatement) {
const auto *type = ctxt.typeMap->getType(sourceHeader->expr, true);
if (const auto *headerUnionType = type->to<IR::Type_HeaderUnion>()) {
for (const auto *field : headerUnionType->fields) {
// Do not set the source member invalid.
if (sourceHeader->member == field->name) {
continue;
}
auto *member = new IR::Member(field->type, sourceHeader->expr, field->name);
ctxt.typeMap->setType(member, field->type);
auto *primitive = mkPrimitive("remove_header"_cs, result);
primitive->emplace_non_null("source_info"_cs, sourceStatement->sourceInfoJsonObj());
primitive->emplace("parameters", new Util::JsonArray({ctxt.conv->convert(member)}));
}
}
}
} // namespace

void ActionConverter::convertActionBody(const IR::Vector<IR::StatOrDecl> *body,
Util::JsonArray *result) {
for (auto s : *body) {
Expand Down Expand Up @@ -146,6 +169,11 @@ void ActionConverter::convertActionBody(const IR::Vector<IR::StatOrDecl> *body,
prim = "add_header"_cs;
} else if (builtin->name == IR::Type_Header::setInvalid) {
prim = "remove_header"_cs;
// If setInvalid is called on any header in a header union, we need to
// invalidate all other headers in the union.
if (const auto *parentStructure = builtin->appliedTo->to<IR::Member>()) {
invalidateOtherHeaderUnionHeaders(parentStructure, *ctxt, result, s);
}
} else if (builtin->name == IR::Type_Stack::push_front) {
BUG_CHECK(mc->arguments->size() == 1, "Expected 1 argument for %1%", mc);
auto arg = ctxt->conv->convert(mc->arguments->at(0)->expression);
Expand Down
83 changes: 63 additions & 20 deletions backends/bmv2/common/parser.cpp
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Expand Up @@ -22,9 +22,39 @@ limitations under the License.
#include "frontends/p4-14/fromv1.0/v1model.h"
#include "frontends/p4/coreLibrary.h"
#include "lib/algorithm.h"
#include "lib/json.h"

namespace P4::BMV2 {

namespace {
/// Invalidates all other headers in a header union except the provided source header.
/// Has no effect if the parent structure is not a header union.
void invalidateOtherHeaderUnionHeaders(const IR::Member *sourceHeader,
const ConversionContext &ctxt, Util::JsonArray *result) {
const auto *type = ctxt.typeMap->getType(sourceHeader->expr, true);
if (const auto *headerUnionType = type->to<IR::Type_HeaderUnion>()) {
for (const auto *field : headerUnionType->fields) {
// Do not set the source member invalid.
if (sourceHeader->member == field->name) {
continue;
}
auto *member = new IR::Member(field->type, sourceHeader->expr, field->name);
ctxt.typeMap->setType(member, field->type);
auto *obj = new Util::JsonObject();
obj->emplace("op", "primitive");
auto *params = mkArrayField(obj, "parameters"_cs);
auto *paramsValue = new Util::JsonObject();
params->append(paramsValue);
auto *pp = mkArrayField(paramsValue, "parameters"_cs);
auto *biObj = ctxt.conv->convert(member);
pp->append(biObj);
paramsValue->emplace("op", "remove_header");
result->append(obj);
}
}
}
} // namespace

cstring ParserConverter::jsonAssignment(const IR::Type *type) {
if (type->is<IR::Type_HeaderUnion>()) return "assign_union"_cs;
if (type->is<IR::Type_Header>() || type->is<IR::Type_Struct>()) return "assign_header"_cs;
Expand All @@ -40,9 +70,10 @@ cstring ParserConverter::jsonAssignment(const IR::Type *type) {
return "set"_cs;
}

Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat) {
auto result = new Util::JsonObject();
auto params = mkArrayField(result, "parameters"_cs);
Util::JsonArray *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat) {
auto *result = new Util::JsonArray();
auto *obj = new Util::JsonObject();
auto *params = mkArrayField(obj, "parameters"_cs);
auto isR = false;
IR::MethodCallExpression *mce2 = nullptr;
if (stat->is<IR::AssignmentStatement>()) {
Expand Down Expand Up @@ -104,7 +135,7 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
auto assign = stat->to<IR::AssignmentStatement>();
auto type = ctxt->typeMap->getType(assign->left, true);
cstring operation = jsonAssignment(type);
result->emplace("op", operation);
obj->emplace("op", operation);
auto l = ctxt->conv->convertLeftValue(assign->left);
bool convertBool = type->is<IR::Type_Boolean>();
auto r = ctxt->conv->convert(assign->right, true, true, convertBool);
Expand All @@ -116,10 +147,11 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
auto wrap = new Util::JsonObject();
wrap->emplace("op", "primitive");
auto params = mkParameters(wrap);
params->append(result);
result = wrap;
params->append(obj);
obj = wrap;
}

result->push_back(obj);
return result;
} else if (stat->is<IR::MethodCallStatement>()) {
auto mce = stat->to<IR::MethodCallStatement>()->methodCall;
Expand All @@ -135,7 +167,7 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
}

cstring ename = argCount == 1 ? "extract"_cs : "extract_VL"_cs;
result->emplace("op", ename);
obj->emplace("op", ename);
auto arg = mce->arguments->at(0);
auto argtype = ctxt->typeMap->getType(arg->expression, true);
if (!argtype->is<IR::Type_Header>()) {
Expand Down Expand Up @@ -206,6 +238,7 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
rwrap->emplace("value", jexpr);
params->append(rwrap);
}
result->push_back(obj);
return result;
} else if (extmeth->method->name.name == corelib.packetIn.lookahead.name) {
// bare lookahead call -- should flag an error if there's not enough
Expand All @@ -218,8 +251,9 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
}
auto arg = mce->arguments->at(0);
auto jexpr = ctxt->conv->convert(arg->expression, true, false);
result->emplace("op", "advance");
obj->emplace("op", "advance");
params->append(jexpr);
result->push_back(obj);
return result;
} else if ((extmeth->originalExternType->name == "InternetChecksum" &&
(extmeth->method->name.name == "clear" ||
Expand All @@ -236,16 +270,17 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
json = ExternConverter::cvtExternObject(ctxt, extmeth, mce, stat, true);
}
if (json) {
result->emplace("op", "primitive");
obj->emplace("op", "primitive");
params->append(json);
}
result->push_back(obj);
return result;
}
} else if (minst->is<P4::ExternFunction>()) {
auto extfn = minst->to<P4::ExternFunction>();
auto extFuncName = extfn->method->name.name;
if (extFuncName == IR::ParserState::verify) {
result->emplace("op", "verify");
obj->emplace("op", "verify");
BUG_CHECK(mce->arguments->size() == 2, "%1%: Expected 2 arguments", mce);
{
auto cond = mce->arguments->at(0);
Expand All @@ -261,10 +296,9 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
auto jexpr = ctxt->conv->convert(error->expression, true, false);
params->append(jexpr);
}
return result;
} else if (extFuncName == "assert" || extFuncName == "assume") {
BUG_CHECK(mce->arguments->size() == 1, "%1%: Expected 1 argument ", mce);
result->emplace("op", "primitive");
obj->emplace("op", "primitive");
auto paramValue = new Util::JsonObject();
params->append(paramValue);
auto paramsArray = mkArrayField(paramValue, "parameters"_cs);
Expand All @@ -276,12 +310,13 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
} else if (extFuncName == P4V1::V1Model::instance.log_msg.name) {
BUG_CHECK(mce->arguments->size() == 2 || mce->arguments->size() == 1,
"%1%: Expected 1 or 2 arguments", mce);
result->emplace("op", "primitive");
obj->emplace("op", "primitive");
auto ef = minst->to<P4::ExternFunction>();
auto ijson = ExternConverter::cvtExternFunction(ctxt, ef, mce, stat, false);
params->append(ijson);
return result;
}
result->push_back(obj);
return result;
} else if (minst->is<P4::BuiltInMethod>()) {
/* example result:
{
Expand All @@ -293,21 +328,26 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
],
"op" : "primitive"
} */
result->emplace("op", "primitive");
obj->emplace("op", "primitive");

auto bi = minst->to<P4::BuiltInMethod>();
cstring primitive;
auto paramsValue = new Util::JsonObject();
params->append(paramsValue);

auto pp = mkArrayField(paramsValue, "parameters"_cs);
auto obj = ctxt->conv->convert(bi->appliedTo);
pp->append(obj);
auto biObj = ctxt->conv->convert(bi->appliedTo);
pp->append(biObj);

if (bi->name == IR::Type_Header::setValid) {
primitive = "add_header"_cs;
} else if (bi->name == IR::Type_Header::setInvalid) {
primitive = "remove_header"_cs;
// If setInvalid is called on any header in a header union, we need to
// invalidate all other headers in the union.
if (const auto *parentStructure = bi->appliedTo->to<IR::Member>()) {
invalidateOtherHeaderUnionHeaders(parentStructure, *ctxt, result);
}
} else if (bi->name == IR::Type_Stack::push_front ||
bi->name == IR::Type_Stack::pop_front) {
if (bi->name == IR::Type_Stack::push_front)
Expand All @@ -323,6 +363,7 @@ Util::IJson *ParserConverter::convertParserStatement(const IR::StatOrDecl *stat)
}

paramsValue->emplace("op", primitive);
result->push_back(obj);
return result;
}
}
Expand Down Expand Up @@ -560,9 +601,11 @@ bool ParserConverter::preorder(const IR::P4Parser *parser) {
// For the state we use the internal name, not the control-plane name
auto state_id = ctxt->json->add_parser_state(parser_id, state->name);
// convert statements
for (auto s : state->components) {
auto op = convertParserStatement(s);
if (op) ctxt->json->add_parser_op(state_id, op);
for (const auto *s : state->components) {
auto *op = convertParserStatement(s);
for (auto *o : *op) {
ctxt->json->add_parser_op(state_id, o);
}
}
// convert transitions
if (state->selectExpression != nullptr) {
Expand Down
2 changes: 1 addition & 1 deletion backends/bmv2/common/parser.h
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Expand Up @@ -38,7 +38,7 @@ class ParserConverter : public Inspector {
unsigned combine(const IR::Expression *keySet, const IR::ListExpression *select, big_int &value,
big_int &mask, bool &is_vset, cstring &vset_name) const;
Util::IJson *stateName(IR::ID state);
Util::IJson *convertParserStatement(const IR::StatOrDecl *stat);
Util::JsonArray *convertParserStatement(const IR::StatOrDecl *stat);
Util::IJson *convertSelectKey(const IR::SelectExpression *expr);
Util::IJson *convertPathExpression(const IR::PathExpression *expr);
Util::IJson *createDefaultTransition();
Expand Down
2 changes: 1 addition & 1 deletion backends/bmv2/pna_nic/midend.cpp
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Expand Up @@ -130,7 +130,7 @@ PnaNicMidEnd::PnaNicMidEnd(CompilerOptions &options, std::ostream *outStream)
new P4::StrengthReduction(&typeMap),
new P4::EliminateTuples(&typeMap),
new P4::SimplifyComparisons(&typeMap),
new P4::CopyStructures(&typeMap),
new P4::CopyStructures(&typeMap, P4::CopyStructuresConfig()),
new P4::NestedStructs(&typeMap),
new P4::SimplifySelectList(&typeMap),
new P4::RemoveSelectBooleans(&typeMap),
Expand Down
2 changes: 1 addition & 1 deletion backends/bmv2/psa_switch/midend.cpp
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Expand Up @@ -131,7 +131,7 @@ PsaSwitchMidEnd::PsaSwitchMidEnd(CompilerOptions &options, std::ostream *outStre
new P4::StrengthReduction(&typeMap),
new P4::EliminateTuples(&typeMap),
new P4::SimplifyComparisons(&typeMap),
new P4::CopyStructures(&typeMap),
new P4::CopyStructures(&typeMap, P4::CopyStructuresConfig()),
new P4::NestedStructs(&typeMap),
new P4::SimplifySelectList(&typeMap),
new P4::RemoveSelectBooleans(&typeMap),
Expand Down
2 changes: 1 addition & 1 deletion backends/bmv2/simple_switch/midend.cpp
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Expand Up @@ -98,7 +98,7 @@ SimpleSwitchMidEnd::SimpleSwitchMidEnd(CompilerOptions &options, std::ostream *o
new P4::StrengthReduction(&typeMap),
new P4::EliminateTuples(&typeMap),
new P4::SimplifyComparisons(&typeMap),
new P4::CopyStructures(&typeMap),
new P4::CopyStructures(&typeMap, P4::CopyStructuresConfig()),
new P4::NestedStructs(&typeMap),
new P4::SimplifySelectList(&typeMap),
new P4::RemoveSelectBooleans(&typeMap),
Expand Down
6 changes: 5 additions & 1 deletion backends/dpdk/midend.cpp
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Expand Up @@ -194,7 +194,11 @@ DpdkMidEnd::DpdkMidEnd(CompilerOptions &options, std::ostream *outStream) {
new P4::StrengthReduction(&typeMap),
new P4::EliminateTuples(&typeMap),
new P4::SimplifyComparisons(&typeMap),
new P4::CopyStructures(&typeMap, false /* errorOnMethodCall */),
new P4::CopyStructures(&typeMap, P4::CopyStructuresConfig{
/*errorOnMethodCall*/ false,
/*copyHeaders*/ false,
/*expandUnions*/ true,
}),
new P4::NestedStructs(&typeMap),
new P4::SimplifySelectList(&typeMap),
new P4::RemoveSelectBooleans(&typeMap),
Expand Down
6 changes: 5 additions & 1 deletion backends/p4test/midend.cpp
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Expand Up @@ -102,7 +102,11 @@ MidEnd::MidEnd(CompilerOptions &options, std::ostream *outStream) {
new P4::StrengthReduction(&typeMap),
new P4::EliminateTuples(&typeMap),
new P4::SimplifyComparisons(&typeMap),
new P4::CopyStructures(&typeMap, false),
new P4::CopyStructures(&typeMap, P4::CopyStructuresConfig{
/*errorOnMethodCall*/ false,
/*copyHeaders*/ false,
/*expandUnions*/ true,
}),
new P4::NestedStructs(&typeMap),
new P4::StrengthReduction(&typeMap),
new P4::SimplifySelectList(&typeMap),
Expand Down
8 changes: 7 additions & 1 deletion backends/p4tools/common/compiler/midend.cpp
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Expand Up @@ -121,7 +121,13 @@ void MidEnd::addDefaultPasses() {
new P4::SimplifyComparisons(&typeMap),
// Expand header and struct assignments into sequences of field assignments.
new PassRepeated({
new P4::CopyStructures(&typeMap, false, true, nullptr),
new P4::CopyStructures(&typeMap,
{
/*errorOnMethodCall*/ false,
/*copyHeaders*/ true,
/*expandUnions*/ false,
},
nullptr),
}),
new P4::RemoveParserControlFlow(&typeMap),
// Flatten nested list expressions.
Expand Down
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