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Optimize some slice copies

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Cache length & ptr in DSliceValue, so that e.g. a pair constructed from
a constant length and some ptr keeps returning a constant length instead
of an extractvalue instruction every time the length is needed.

This enables checking for matching constant lengths when copying slices
and makes `test1()` in runnable/betterc.d work (memcpy instead of
_d_array_slice_copy call):

```
int[10] a1 = void;
int[10] a2 = void;
a1[] = a2[];
```

(more or less equivalent to `a1 = a2`, which is already optimized)
This commit is contained in:
Martin Kinkelin 2019-01-09 23:50:41 +01:00
parent a911e72c86
commit 2fb5098f48
3 changed files with 34 additions and 6 deletions
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20
gen/arrays.cpp
View file

@ -275,8 +275,18 @@ void DtoArrayAssign(Loc &loc, DValue *lhs, DValue *rhs, int op,
LLValue *lhsSize = computeSize(lhsLength, elementSize);
DtoMemSetZero(lhsPtr, lhsSize);
} else {
const bool knownInBounds =
bool knownInBounds =
isConstructing || (t->ty == Tsarray && t2->ty == Tsarray);
if (!knownInBounds) {
if (auto constLhsLength = llvm::dyn_cast<LLConstantInt>(lhsLength)) {
if (auto constRhsLength =
llvm::dyn_cast<LLConstantInt>(rhsLength)) {
if (constLhsLength->getValue() == constRhsLength->getValue()) {
knownInBounds = true;
}
}
}
}
copySlice(loc, lhsPtr, lhsLength, rhsPtr, rhsLength, elementSize,
knownInBounds);
}
@ -1194,7 +1204,9 @@ LLValue *DtoArrayLen(DValue *v) {
if (v->isLVal()) {
return DtoLoad(DtoGEPi(DtoLVal(v), 0, 0), ".len");
}
return gIR->ir->CreateExtractValue(DtoRVal(v), 0, ".len");
auto slice = v->isSlice();
assert(slice);
return slice->getLength();
}
if (t->ty == Tsarray) {
assert(!v->isSlice());
@ -1222,7 +1234,9 @@ LLValue *DtoArrayPtr(DValue *v) {
} else if (v->isLVal()) {
ptr = DtoLoad(DtoGEPi(DtoLVal(v), 0, 1), ".ptr");
} else {
ptr = gIR->ir->CreateExtractValue(DtoRVal(v), 1, ".ptr");
auto slice = v->isSlice();
assert(slice);
ptr = slice->getPtr();
}
} else if (t->ty == Tsarray) {
assert(!v->isSlice());