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[snippy] Dump initial registers without model #421

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[snippy] Dump initial registers without model #421

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e9ab843
[snippy] Support dump-initial-registers-yaml without model plugin
MaxGud10 Apr 2, 2026
20fc6cf
[snippy] Dump initial registers without model plugin
MaxGud10 Jun 20, 2026
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10 changes: 10 additions & 0 deletions llvm/test/tools/llvm-snippy/dump-initial-registers-no-model.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
# RUN: llvm-snippy %s -mtriple=riscv64 --model-plugin=None -num-instrs=10 \
# RUN: --init-regs-in-elf \
# RUN: --dump-initial-registers-yaml=%t.initial-regs.yaml
# RUN: test -s %t.initial-regs.yaml

include:
- "Inputs/sections.yaml"

histogram:
- [ADD, 1]
8 changes: 8 additions & 0 deletions llvm/tools/llvm-snippy/include/snippy/Generator/SnippyModule.h
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Expand Up @@ -318,6 +318,12 @@ class SnippyProgramContext final {
const IRegisterState &
getInitialRegisterState(const TargetSubtargetInfo &ST) const;

void dumpInitialRegisterState(StringRef YamlPath) const;

@arromanoff arromanoff Jul 2, 2026

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Hence this overload is redundant

void dumpInitialRegisterState(StringRef YamlPath,
const TargetSubtargetInfo &ST) const;

@arromanoff arromanoff Jul 2, 2026

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I'd also separate concerns here. Let's separate fetching this state and dumping it. So in FlowGenerator you can do:

auto &RegState = ProgramCtx.getInitialRegisterState(ST);
RegState.saveAsYAMLFile(PassCfg.RegistersConfig.InitialStateOutputYaml);


const IRegisterState &getInitialRegisterState() const;

bool hasProgramStateSaveSpace() const { return PGSK.get(); }
const auto &getProgramStateSaveSpace() const { return *PGSK; }
auto &getProgramStateSaveSpace() { return *PGSK; }
Expand Down Expand Up @@ -364,6 +370,8 @@ class SnippyProgramContext final {
std::unique_ptr<MemoryManager> MemManager;
std::unique_ptr<SMCManagerT> SMCManager;

const TargetSubtargetInfo *InitialStateSubtarget = nullptr;

constexpr static auto SmallStringDefaultSize = 16;

std::optional<SectionDesc> ROMSection;
Expand Down
3 changes: 3 additions & 0 deletions llvm/tools/llvm-snippy/lib/FlowGenerator.cpp
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Expand Up @@ -504,6 +504,9 @@ GeneratorResult FlowGenerator::generate(LLVMState &State,

} else {

ProgContext.dumpInitialRegisterState(
PassCfg.RegistersConfig.InitialStateOutputYaml);

Comment on lines +507 to +509

@arromanoff arromanoff Jul 2, 2026

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There on the call site you can get the subtarget

auto *EntryFunc  = MainModule.getFunction(ProgramCfg.EntryPointName);
assert(EntryFunc);
auto &ST = State.getSubtargetImpl(*EntryFunc);
// Now you can call
dumpInitialRegisterState(PassCfg.RegistersConfig.InitialStateOutputYaml, ST);

snippy::warn(WarningName::NoModelExec, State.getCtx(),
"Skipping snippet execution on the model",
"model was set to 'None'.");
Expand Down
2 changes: 1 addition & 1 deletion llvm/tools/llvm-snippy/lib/Generator/SimulatorContextWrapperPass.cpp
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Expand Up @@ -227,7 +227,7 @@ Error SimulatorContext::runSimulator(const RunInfo &RI) {
// StartPC location may be updated since last time it was configured.

I.setPC(ElfData->ProgStart);
I.dumpCurrentRegState(InitialStateOutputYaml);
ProgCtx.dumpInitialRegisterState(InitialStateOutputYaml, I.getSubTarget());

if (ElfData->ProgEnd == std::nullopt)
return createStringError(
Expand Down
33 changes: 33 additions & 0 deletions llvm/tools/llvm-snippy/lib/Generator/SnippyModule.cpp
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Expand Up @@ -285,6 +285,38 @@ const IRegisterState &SnippyProgramContext::getInitialRegisterState(
return *InitialMachineState;
}

void SnippyProgramContext::dumpInitialRegisterState(
StringRef YamlPath, const TargetSubtargetInfo &ST) const {
if (YamlPath.empty())
return;

std::error_code EC;
raw_fd_ostream File(YamlPath, EC);
if (EC)
snippy::fatal(State->getCtx(), "Failed to dump initial registers",
"cannot open file \"" + Twine(YamlPath) +
"\": " + EC.message());

getInitialRegisterState(ST).saveAsYAMLFile(File);
}

void SnippyProgramContext::dumpInitialRegisterState(StringRef YamlPath) const {
if (YamlPath.empty())
return;

assert(
InitialStateSubtarget &&
"Initial register state requested before target context initialization");
dumpInitialRegisterState(YamlPath, *InitialStateSubtarget);
}

const IRegisterState &SnippyProgramContext::getInitialRegisterState() const {
assert(InitialStateSubtarget &&
"Initial register state requested before target context "
"initialization");
return getInitialRegisterState(*InitialStateSubtarget);
}

SnippyProgramContext::SnippyProgramContext(LLVMState &State,
RegisterGenerator &RegGen,
std::vector<RegPool> Pools,
Expand Down Expand Up @@ -318,6 +350,7 @@ void SnippyProgramContext::createTargetContext(const Config &Cfg,
const TargetSubtargetInfo &STI,
const RegPoolWrapper &RP) {
assert(!TargetContext && "Double context insertion");
InitialStateSubtarget = &STI;

@arromanoff arromanoff Jul 2, 2026

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I don't like this new member and it's usage
We dump register state after we generated code so there're no problems with getting subtarget from LLVMState at this point. Just call getLLVMState().getSubtargetImpl

TargetContext =
State->getSnippyTarget().createTargetContext(*State, Cfg, &STI, RP);
}
Expand Down
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