tbaeder created this revision.
tbaeder added reviewers: aaron.ballman, erichkeane, tahonermann, shafik.
Herald added a project: All.
tbaeder requested review of this revision.
Herald added a project: clang.
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This only works on integrals for now.
Add four new opcodes, `Inc`, `IncPop`, `Dec` and `DecPop`. The `*Pop` variants
don't leave anything on the stack and exist because the common case is that the
result is unused.
There are still a few corner cases left like floating values, pointers, and
over/underflow handling.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D136423
Files:
clang/lib/AST/Interp/ByteCodeExprGen.cpp
clang/lib/AST/Interp/Interp.h
clang/lib/AST/Interp/Opcodes.td
clang/test/AST/Interp/arrays.cpp
clang/test/AST/Interp/literals.cpp
Index: clang/test/AST/Interp/literals.cpp
===================================================================
--- clang/test/AST/Interp/literals.cpp
+++ clang/test/AST/Interp/literals.cpp
@@ -361,3 +361,52 @@
constexpr double db = true;
static_assert(db == 1.0, "");
};
+
+#if __cplusplus >= 202002L
+namespace IncDec {
+ constexpr int zero() {
+ int a = 0;
+ a++;
+ ++a;
+ a--;
+ --a;
+ return a;
+ }
+ static_assert(zero() == 0, "");
+
+ constexpr int three() {
+ int a = 0;
+ return ++a + ++a; // expected-warning {{multiple unsequenced modifications to 'a'}} \
+ // ref-warning {{multiple unsequenced modifications to 'a'}} \
+
+ }
+ static_assert(three() == 3, "");
+
+ constexpr bool incBool() {
+ bool b = false;
+ return ++b; // expected-error {{ISO C++17 does not allow incrementing expression of type bool}} \
+ // ref-error {{ISO C++17 does not allow incrementing expression of type bool}}
+ }
+ static_assert(incBool(), "");
+
+ constexpr int uninit() {
+ int a;
+ ++a; // ref-note {{increment of uninitialized}} \
+ // FIXME: Should also be rejected by new interpreter
+ return 1;
+ }
+ static_assert(uninit(), ""); // ref-error {{not an integral constant expression}} \
+ // ref-note {{in call to 'uninit()'}}
+
+ constexpr int OverUnderFlow() { // ref-error {{never produces a constant expression}}
+ int a = INT_MAX;
+ ++a; // ref-note {{is outside the range}}
+ // FIXME: Overflow
+
+ int b = INT_MIN;
+ --b; // FIXME: Underflow
+
+ return -1;
+ }
+};
+#endif
Index: clang/test/AST/Interp/arrays.cpp
===================================================================
--- clang/test/AST/Interp/arrays.cpp
+++ clang/test/AST/Interp/arrays.cpp
@@ -180,3 +180,18 @@
constexpr int x = arr.a[0];
}
};
+
+namespace IncDec {
+ // FIXME: Pointer arithmethic needs to be supported in inc/dec
+ // unary operators
+#if 0
+ constexpr int getNextElem(const int *A, int I) {
+ const int *B = (A + I);
+ ++B;
+ return *B;
+ }
+ constexpr int E[] = {1,2,3,4};
+
+ static_assert(getNextElem(E, 1) == 3);
+#endfi
+};
Index: clang/lib/AST/Interp/Opcodes.td
===================================================================
--- clang/lib/AST/Interp/Opcodes.td
+++ clang/lib/AST/Interp/Opcodes.td
@@ -452,6 +452,11 @@
let HasGroup = 1;
}
+def Inc: IntegerOpcode;
+def IncPop : IntegerOpcode;
+def Dec: IntegerOpcode;
+def DecPop: IntegerOpcode;
+
// [Real] -> [Real]
def Neg: Opcode {
let Types = [NonPtrTypeClass];
Index: clang/lib/AST/Interp/Interp.h
===================================================================
--- clang/lib/AST/Interp/Interp.h
+++ clang/lib/AST/Interp/Interp.h
@@ -328,6 +328,70 @@
return true;
}
+/// 1) Pops a pointer from the stack
+/// 2) Load the value from the pointer
+/// 3) Writes the value increased by one back to the pointer
+/// 4) Pushes the original (pre-inc) value on the stack.
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool Inc(InterpState &S, CodePtr OpPC) {
+ // FIXME: Check initialization of Ptr
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ T Value = Ptr.deref<T>();
+ T Result;
+ if (T::increment(Value, &Result))
+ return false;
+ Ptr.deref<T>() = Result;
+ S.Stk.push<T>(Value);
+ return true;
+}
+
+/// 1) Pops a pointer from the stack
+/// 2) Load the value from the pointer
+/// 3) Writes the value increased by one back to the pointer
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool IncPop(InterpState &S, CodePtr OpPC) {
+ // FIXME: Check initialization of Ptr
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ T Value = Ptr.deref<T>();
+ T Result;
+ if (T::increment(Value, &Result))
+ return false;
+ Ptr.deref<T>() = Result;
+ return true;
+}
+
+/// 1) Pops a pointer from the stack
+/// 2) Load the value from the pointer
+/// 3) Writes the value decreased by one back to the pointer
+/// 4) Pushes the original (pre-dec) value on the stack.
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool Dec(InterpState &S, CodePtr OpPC) {
+ // FIXME: Check initialization of Ptr
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ T Value = Ptr.deref<T>();
+ T Result;
+ if (T::decrement(Value, &Result))
+ return false;
+ Ptr.deref<T>() = Result;
+ S.Stk.push<T>(Value);
+ return true;
+}
+
+/// 1) Pops a pointer from the stack
+/// 2) Load the value from the pointer
+/// 3) Writes the value decreased by one back to the pointer
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool DecPop(InterpState &S, CodePtr OpPC) {
+ // FIXME: Check initialization of Ptr
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ T Value = Ptr.deref<T>();
+ T Result;
+ if (T::decrement(Value, &Result))
+ return false;
+ Ptr.deref<T>() = Result;
+ return true;
+}
+
/// 1) Pops the value from the stack.
/// 2) Pushes the bitwise complemented value on the stack (~V).
template <PrimType Name, class T = typename PrimConv<Name>::T>
Index: clang/lib/AST/Interp/ByteCodeExprGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -1226,35 +1226,81 @@
template <class Emitter>
bool ByteCodeExprGen<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
- if (DiscardResult)
- return true;
-
const Expr *SubExpr = E->getSubExpr();
+ Optional<PrimType> T = classify(SubExpr->getType());
+ // TODO: Support pointers for inc/dec operators.
switch (E->getOpcode()) {
- case UO_PostInc: // x++
- case UO_PostDec: // x--
- case UO_PreInc: // --x
- case UO_PreDec: // ++x
- return false;
+ case UO_PostInc: { // x++
+ if (!this->visit(SubExpr))
+ return false;
+
+ if (DiscardResult)
+ return this->emitIncPop(*T, E);
+
+ return this->emitInc(*T, E);
+ }
+ case UO_PostDec: { // x--
+ if (!this->visit(SubExpr))
+ return false;
+
+ if (DiscardResult)
+ return this->emitDecPop(*T, E);
+
+ return this->emitDec(*T, E);
+ }
+ case UO_PreInc: { // ++x
+ if (!this->visit(SubExpr))
+ return false;
+
+ // Post-inc and pre-inc are the same if the value is to be discarded.
+ if (DiscardResult)
+ return this->emitIncPop(*T, E);
+ this->emitLoad(*T, E);
+ this->emitConst(E, 1);
+ this->emitAdd(*T, E);
+ return this->emitStore(*T, E);
+ }
+ case UO_PreDec: { // --x
+ if (!this->visit(SubExpr))
+ return false;
+
+ // Post-dec and pre-dec are the same if the value is to be discarded.
+ if (DiscardResult)
+ return this->emitDecPop(*T, E);
+
+ this->emitLoad(*T, E);
+ this->emitConst(E, 1);
+ this->emitSub(*T, E);
+ return this->emitStore(*T, E);
+ }
case UO_LNot: // !x
if (!this->visit(SubExpr))
return false;
+ // The Inv doesn't change anything, so skip it if we don't need the result.
+ if (DiscardResult)
+ return this->emitPop(*T, E);
return this->emitInvBool(E);
case UO_Minus: // -x
if (!this->visit(SubExpr))
return false;
- if (Optional<PrimType> T = classify(E->getType()))
- return this->emitNeg(*T, E);
- return false;
+ if (DiscardResult)
+ return this->emitPop(*T, E);
+ return this->emitNeg(*T, E);
case UO_Plus: // +x
- return this->visit(SubExpr); // noop
-
+ if (!this->visit(SubExpr)) // noop
+ return false;
+ if (DiscardResult)
+ return this->emitPop(*T, E);
+ return true;
case UO_AddrOf: // &x
// We should already have a pointer when we get here.
- return this->visit(SubExpr);
-
+ if (!this->visit(SubExpr))
+ return false;
+ if (DiscardResult)
+ return this->emitPop(*T, E);
+ return true;
case UO_Deref: // *x
return dereference(
SubExpr, DerefKind::Read,
@@ -1268,9 +1314,9 @@
case UO_Not: // ~x
if (!this->visit(SubExpr))
return false;
- if (Optional<PrimType> T = classify(E->getType()))
- return this->emitComp(*T, E);
- return false;
+ if (DiscardResult)
+ return this->emitPop(*T, E);
+ return this->emitComp(*T, E);
case UO_Real: // __real x
case UO_Imag: // __imag x
case UO_Extension:
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