From 1958e17734d911e7438fbfc00a214e80235a1256 Mon Sep 17 00:00:00 2001 From: Frits van Bommel Date: Sat, 6 Jun 2009 20:16:13 +0200 Subject: [PATCH] Rewrite `StructLiteralExp::toElem` to store individual fields instead of generating a constant to fill the entire struct with a single `store`. This is much more efficient at compile time (fixing #320) and vastly reduces the size of the emitted code. Since LLVM no longer needs to keep the data for all fields in "registers" until the store happens, it should also be more efficient at run time in cases where the fields aren't assigned with constants. There's also some code clean-up by removing duplicated logic. --- gen/llvmhelpers.cpp | 72 --------------------------------- gen/llvmhelpers.h | 2 - gen/toir.cpp | 97 +++++++++++++++------------------------------ 3 files changed, 33 insertions(+), 138 deletions(-) diff --git a/gen/llvmhelpers.cpp b/gen/llvmhelpers.cpp index bfbbab2b..1662a0e7 100644 --- a/gen/llvmhelpers.cpp +++ b/gen/llvmhelpers.cpp @@ -1226,78 +1226,6 @@ LLConstant* DtoConstExpInit(Loc loc, Type* type, Expression* exp) ////////////////////////////////////////////////////////////////////////////////////////// -static LLValue* expand_value_to_sarray(Type *base, Expression* exp) -{ - Logger::println("building type %s from expression (%s) of type %s", base->toChars(), exp->toChars(), exp->type->toChars()); - const LLType* dstTy = DtoType(base); - if (Logger::enabled()) - Logger::cout() << "final llvm type requested: " << *dstTy << '\n'; - - // get initial value - LLValue* val = exp->toElem(gIR)->getRVal(); - if (DtoIsPassedByRef(exp->type)) - val = DtoLoad(val); - - Type* expbase = exp->type->toBasetype(); - Logger::println("expbase: %s", expbase->toChars()); - Type* t = base->toBasetype(); - - LLSmallVector dims; - - while(1) - { - Logger::println("t: %s", t->toChars()); - if (t->equals(expbase)) - break; - assert(t->ty == Tsarray); - TypeSArray* tsa = (TypeSArray*)t; - dims.push_back(tsa->dim->toInteger()); - assert(t->nextOf()); - t = t->nextOf()->toBasetype(); - } - - size_t i = dims.size(); - assert(i); - - std::vector inits; - while (i--) - { - // start with undefined array - const LLArrayType* arrty = LLArrayType::get(val->getType(), dims[i]); - LLValue* tmp = llvm::UndefValue::get(arrty); - for (size_t j = 0; j < dims[i]; j++) - { - tmp = gIR->ir->CreateInsertValue(tmp, val, j); - } - val = tmp; - } - - return val; -} - -LLValue* DtoExprValue(Type* type, Expression* e) -{ - Type* t1 = e->type->toBasetype(); - Type* t2 = type->toBasetype(); - - // expand static arrays - if (t2->ty == Tsarray && !t1->equals(t2)) - { - return expand_value_to_sarray(t2, e); - } - // or not - else - { - DValue* dv = e->toElem(gIR); - LLValue* v = dv->getRVal(); - if (DtoIsPassedByRef(e->type)) - v = DtoLoad(v); - return v; - } -} - -////////////////////////////////////////////////////////////////////////////////////////// - void DtoAnnotation(const char* str) { std::string s("CODE: "); diff --git a/gen/llvmhelpers.h b/gen/llvmhelpers.h index a62f8cd1..b79261b5 100644 --- a/gen/llvmhelpers.h +++ b/gen/llvmhelpers.h @@ -105,8 +105,6 @@ LLConstant* DtoConstInitializer(Loc loc, Type* type, Initializer* init); LLConstant* DtoConstExpInit(Loc loc, Type* t, Expression* exp); DValue* DtoInitializer(LLValue* target, Initializer* init); -LLValue* DtoExprValue(Type* type, Expression* e); - // annotation generator void DtoAnnotation(const char* str); diff --git a/gen/toir.cpp b/gen/toir.cpp index 1aac027a..db913148 100644 --- a/gen/toir.cpp +++ b/gen/toir.cpp @@ -2409,11 +2409,15 @@ LLConstant* ArrayLiteralExp::toConstElem(IRState* p) ////////////////////////////////////////////////////////////////////////////////////////// -// building a struct literal is pretty much the same as building a default initializer. - -extern size_t add_zeros(std::vector& values, size_t diff); extern LLConstant* get_default_initializer(VarDeclaration* vd, Initializer* init); +static LLValue* write_zeroes(LLValue* mem, unsigned start, unsigned end) { + mem = DtoBitCast(mem, getVoidPtrType()); + LLValue* gep = DtoGEPi1(mem, start, ".padding"); + DtoMemSetZero(gep, DtoConstSize_t(end - start)); + return mem; +} + DValue* StructLiteralExp::toElem(IRState* p) { Logger::print("StructLiteralExp::toElem: %s @ %s\n", toChars(), type->toChars()); @@ -2422,97 +2426,62 @@ DValue* StructLiteralExp::toElem(IRState* p) // make sure the struct is fully resolved sd->codegen(Type::sir); - // final list of values to put in the struct - std::vector initvalues; - - // offset tracker - size_t offset = 0; - - // align(1) struct S { ... } - bool packed = sd->type->alignsize() == 1; + // alloca a stack slot + LLValue* mem = DtoRawAlloca(DtoType(type), 0, ".structliteral"); // ready elements data assert(elements && "struct literal has null elements"); - size_t nexprs = elements->dim;; + size_t nexprs = elements->dim; Expression** exprs = (Expression**)elements->data; + LLValue* voidptr = mem; + unsigned offset = 0; + // go through fields ArrayIter it(sd->fields); for (; !it.done(); it.next()) { VarDeclaration* vd = it.get(); + // don't re-initialize unions if (vd->offset < offset) { IF_LOG Logger::println("skipping field: %s %s (+%u)", vd->type->toChars(), vd->toChars(), vd->offset); continue; } + // initialize any padding so struct comparisons work + if (vd->offset != offset) + voidptr = write_zeroes(voidptr, offset, vd->offset); + offset = vd->offset + vd->type->size(); - IF_LOG Logger::println("using field: %s %s (+%u)", vd->type->toChars(), vd->toChars(), vd->offset); + IF_LOG Logger::println("initializing field: %s %s (+%u)", vd->type->toChars(), vd->toChars(), vd->offset); - // get next aligned offset for this field - size_t alignedoffset = offset; - if (!packed) - { - alignedoffset = realignOffset(alignedoffset, vd->type); - } - - // insert explicit padding? - if (alignedoffset < vd->offset) - { - add_zeros(initvalues, vd->offset - alignedoffset); - } - - // add initializer + // get initializer Expression* expr = (it.index < nexprs) ? exprs[it.index] : NULL; IF_LOG Logger::println("expr: %p", expr); + DValue* val; + DConstValue cv(vd->type, NULL); // Only used in one branch; value is set beforehand if (expr) { IF_LOG Logger::println("expr %zu = %s", it.index, expr->toChars()); - LLValue* v = DtoExprValue(vd->type, expr); - initvalues.push_back(v); + val = expr->toElem(gIR); } else { IF_LOG Logger::println("using default initializer"); - initvalues.push_back(get_default_initializer(vd, NULL)); + cv.c = get_default_initializer(vd, NULL); + val = &cv; } - // advance offset to right past this field - offset = vd->offset + vd->type->size(); + // get a pointer to this field + DVarValue field(vd->type, vd, DtoIndexStruct(mem, sd, vd)); + + // store the initializer there + DtoAssign(loc, &field, val); } - - // tail padding? - if (offset < sd->structsize) - { - add_zeros(initvalues, sd->structsize - offset); - } - - // build type - std::vector valuetypes; - - size_t n = initvalues.size(); - valuetypes.reserve(n); - - for (size_t i = 0; i < n; i++) - { - valuetypes.push_back(initvalues[i]->getType()); - } - - const LLType* st = llvm::StructType::get(valuetypes, packed); - - // alloca a stack slot - LLValue* mem = DtoRawAlloca(st, 0, ".structliteral"); - - // fill in values - for (size_t i = 0; i < n; i++) - { - LLValue* addr = DtoGEPi(mem, 0, i); - p->ir->CreateStore(initvalues[i], addr); - } - - // cast to default struct type - mem = DtoBitCast(mem, DtoType(sd->type->pointerTo())); + // initialize trailing padding + if (sd->structsize != offset) + write_zeroes(voidptr, offset, sd->structsize); // return as a var return new DVarValue(type, mem);