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Don't emit empty files with low split limits (verilator#2961)
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Attempt to split output files when we know a function will actually be
emitted, otherwise we might end up with empty files.
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@gezalore
gezalore committed May 15, 2021
1 parent 5e95cc9 commit 828f78e
Showing 1 changed file with 53 additions and 44 deletions.
97 changes: 53 additions & 44 deletions src/V3EmitC.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1343,6 +1343,7 @@ unsigned EmitVarTspSorter::s_serialNext = 0;
class EmitCImp final : EmitCStmts {
// MEMBERS
AstNodeModule* m_modp = nullptr;
AstNodeModule* m_fileModp = nullptr; // Files (names, headers) constructed using this module
std::vector<AstChangeDet*> m_blkChangeDetVec; // All encountered changes in block
bool m_slow = false; // Creating __Slow file
bool m_fast = false; // Creating non __Slow file (or both)
Expand Down Expand Up @@ -1391,8 +1392,8 @@ class EmitCImp final : EmitCStmts {
}
}

V3OutCFile* newOutCFile(AstNodeModule* modp, bool slow, bool source, int filenum = 0) {
string filenameNoExt = v3Global.opt.makeDir() + "/" + prefixNameProtect(modp);
V3OutCFile* newOutCFile(bool slow, bool source, int filenum = 0) {
string filenameNoExt = v3Global.opt.makeDir() + "/" + prefixNameProtect(m_fileModp);
if (filenum) filenameNoExt += "__" + cvtToStr(filenum);
filenameNoExt += (slow ? "__Slow" : "");
V3OutCFile* ofp = nullptr;
Expand All @@ -1413,7 +1414,7 @@ class EmitCImp final : EmitCStmts {
}

ofp->putsHeader();
if (modp->isTop() && !source) {
if (m_fileModp->isTop() && !source) {
ofp->puts("// DESCR"
"IPTION: Verilator output: Primary design header\n");
ofp->puts("//\n");
Expand Down Expand Up @@ -1501,7 +1502,10 @@ class EmitCImp final : EmitCStmts {
}

virtual void visit(AstMTaskBody* nodep) override {
ExecMTask* mtp = nodep->execMTaskp();
maybeSplit();
splitSizeInc(10);

const ExecMTask* const mtp = nodep->execMTaskp();
puts("\n");
puts("void ");
puts(prefixNameProtect(m_modp) + "::" + protect(mtp->cFuncName()));
Expand All @@ -1525,6 +1529,8 @@ class EmitCImp final : EmitCStmts {
if (nodep->dpiImport()) return;
if (!(nodep->slow() ? m_slow : m_fast)) return;

maybeSplit();

m_blkChangeDetVec.clear();

splitSizeInc(nodep);
Expand Down Expand Up @@ -1868,16 +1874,16 @@ class EmitCImp final : EmitCStmts {
void emitSavableImp(AstNodeModule* modp);
void emitTextSection(AstType type);
// High level
void emitImpTop(AstNodeModule* modp);
void emitImp(AstNodeModule* fileModp, AstNodeModule* modp);
void emitImpTop();
void emitImp(AstNodeModule* modp);
void emitSettleLoop(const std::string& eval_call, bool initial);
void emitWrapEval(AstNodeModule* modp);
void emitWrapFast(AstNodeModule* modp);
void emitMTaskState();
void emitMTaskVertexCtors(bool* firstp);
void emitIntTop(AstNodeModule* modp);
void emitInt(AstNodeModule* modp);
void maybeSplit(AstNodeModule* modp);
void maybeSplit();

public:
EmitCImp() = default;
Expand Down Expand Up @@ -3351,23 +3357,23 @@ void EmitCImp::emitInt(AstNodeModule* modp) {

//----------------------------------------------------------------------

void EmitCImp::emitImpTop(AstNodeModule* fileModp) {
void EmitCImp::emitImpTop() {
puts("\n");
puts("#include \"" + prefixNameProtect(fileModp) + ".h\"\n");
puts("#include \"" + prefixNameProtect(m_fileModp) + ".h\"\n");
puts("#include \"" + symClassName() + ".h\"\n");

if (v3Global.dpi()) {
puts("\n");
puts("#include \"verilated_dpi.h\"\n");
}

emitModCUse(fileModp, VUseType::IMP_INCLUDE);
emitModCUse(fileModp, VUseType::IMP_FWD_CLASS);
emitModCUse(m_fileModp, VUseType::IMP_INCLUDE);
emitModCUse(m_fileModp, VUseType::IMP_FWD_CLASS);

emitTextSection(AstType::atScImpHdr);
}

void EmitCImp::emitImp(AstNodeModule* fileModp, AstNodeModule* modp) {
void EmitCImp::emitImp(AstNodeModule* modp) {
puts("\n//==========\n");
if (m_slow) {
string section;
Expand All @@ -3389,37 +3395,33 @@ void EmitCImp::emitImp(AstNodeModule* fileModp, AstNodeModule* modp) {

// Blocks
for (AstNode* nodep = modp->stmtsp(); nodep; nodep = nodep->nextp()) {
if (AstCFunc* funcp = VN_CAST(nodep, CFunc)) {
maybeSplit(fileModp);
mainDoFunc(funcp);
}
if (AstCFunc* funcp = VN_CAST(nodep, CFunc)) { mainDoFunc(funcp); }
}
}

//######################################################################

void EmitCImp::maybeSplit(AstNodeModule* fileModp) {
if (splitNeeded()) {
// Splitting file, so using parallel build.
v3Global.useParallelBuild(true);
// Close old file
VL_DO_CLEAR(delete m_ofp, m_ofp = nullptr);
// Open a new file
m_ofp = newOutCFile(fileModp, !m_fast, true /*source*/, splitFilenumInc());
emitImpTop(fileModp);
}
splitSizeInc(10); // Even blank functions get a file with a low csplit
void EmitCImp::maybeSplit() {
if (!splitNeeded()) return;

// Splitting file, so using parallel build.
v3Global.useParallelBuild(true);
// Close old file
VL_DO_CLEAR(delete m_ofp, m_ofp = nullptr);
// Open a new file
m_ofp = newOutCFile(!m_fast, true /*source*/, splitFilenumInc());
emitImpTop();
}

void EmitCImp::mainInt(AstNodeModule* modp) {
AstNodeModule* fileModp = modp; // Filename constructed using this module
m_modp = modp;
m_fileModp = modp;
m_slow = true;
m_fast = true;

UINFO(5, " Emitting " << prefixNameProtect(modp) << endl);

m_ofp = newOutCFile(fileModp, false /*slow*/, false /*source*/);
m_ofp = newOutCFile(false /*slow*/, false /*source*/);
emitIntTop(modp);
emitInt(modp);
if (AstClassPackage* packagep = VN_CAST(modp, ClassPackage)) {
Expand All @@ -3434,23 +3436,23 @@ void EmitCImp::mainInt(AstNodeModule* modp) {

void EmitCImp::mainImp(AstNodeModule* modp, bool slow) {
// Output a module
AstNodeModule* fileModp = modp; // Filename constructed using this module
m_modp = modp;
m_fileModp = modp;
m_slow = slow;
m_fast = !slow;

UINFO(5, " Emitting " << prefixNameProtect(modp) << endl);

m_ofp = newOutCFile(fileModp, !m_fast, true /*source*/);
emitImpTop(fileModp);
emitImp(fileModp, modp);
m_ofp = newOutCFile(!m_fast, true /*source*/);
emitImpTop();
emitImp(modp);

if (AstClassPackage* packagep = VN_CAST(modp, ClassPackage)) {
// Put the non-static class implementation in same C++ files as
// often optimizations are possible when both are seen by the
// compiler together
m_modp = packagep->classp();
emitImp(fileModp, packagep->classp());
emitImp(packagep->classp());
m_modp = modp;
}

Expand All @@ -3463,7 +3465,6 @@ void EmitCImp::mainImp(AstNodeModule* modp, bool slow) {
vxp = vxp->verticesNextp()) {
const ExecMTask* mtaskp = dynamic_cast<const ExecMTask*>(vxp);
if (mtaskp->threadRoot()) {
maybeSplit(fileModp);
// Only define one function for all the mtasks packed on
// a given thread. We'll name this function after the
// root mtask though it contains multiple mtasks' worth
Expand Down Expand Up @@ -3938,21 +3939,29 @@ void V3EmitC::emitc() {
for (AstNodeModule* nodep = v3Global.rootp()->modulesp(); nodep;
nodep = VN_CAST(nodep->nextp(), NodeModule)) {
if (VN_IS(nodep, Class)) continue; // Imped with ClassPackage
// clang-format off
EmitCImp cint; cint.mainInt(nodep);
cint.mainImp(nodep, true);
{ EmitCImp fast; fast.mainImp(nodep, false); }
// clang-format on
{
EmitCImp cint;
cint.mainInt(nodep);
cint.mainImp(nodep, true);
}
{
EmitCImp fast;
fast.mainImp(nodep, false);
}
}
}

void V3EmitC::emitcTrace() {
UINFO(2, __FUNCTION__ << ": " << endl);
if (v3Global.opt.trace()) {
// clang-format off
{ EmitCTrace slow(true); slow.main(); }
{ EmitCTrace fast(false); fast.main(); }
// clang-format on
{
EmitCTrace slow(true);
slow.main();
}
{
EmitCTrace fast(false);
fast.main();
}
}
}

Expand Down

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