tbaeder created this revision.
tbaeder added reviewers: aaron.ballman, erichkeane, tahonermann, shafik.
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Add a test case based on `test/SemaCXX/shift.cpp`.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D136532
Files:
clang/lib/AST/Interp/ByteCodeExprGen.cpp
clang/lib/AST/Interp/Interp.h
clang/lib/AST/Interp/Opcodes.td
clang/test/AST/Interp/shifts.cpp
Index: clang/test/AST/Interp/shifts.cpp
===================================================================
--- /dev/null
+++ clang/test/AST/Interp/shifts.cpp
@@ -0,0 +1,103 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -std=c++20 -verify %s
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -std=c++17 -verify=cxx17 %s
+// RUN: %clang_cc1 -std=c++20 -verify=ref %s
+// RUN: %clang_cc1 -std=c++17 -verify=ref-cxx17 %s
+
+#define CHAR_BIT (sizeof(char) * 8)
+#define WORD_BIT (sizeof(int) * 8)
+#define INT_MAX (__INT_MAX__)
+#define INT_MIN (~__INT_MAX__)
+
+
+namespace shifts {
+ constexpr void test() { // ref-error {{constexpr function never produces a constant expression}} \
+ // ref-cxx17-error {{constexpr function never produces a constant expression}}
+
+ char c; // cxx17-warning {{uninitialized variable}} \
+ // ref-cxx17-warning {{uninitialized variable}}
+
+ c = 0 << 0;
+ c = 0 << 1;
+ c = 1 << 0;
+ c = 1 << -0;
+ c = 1 >> -0;
+ c = 1 << -1; // expected-warning {{shift count is negative}} \
+ // cxx17-warning {{shift count is negative}} \
+ // ref-warning {{shift count is negative}} \
+ // ref-note {{negative shift count -1}} \
+ // ref-cxx17-warning {{shift count is negative}} \
+ // ref-cxx17-note {{negative shift count -1}}
+
+ c = 1 >> -1; // expected-warning {{shift count is negative}} \
+ // cxx17-warning {{shift count is negative}} \
+ // ref-warning {{shift count is negative}} \
+ // ref-cxx17-warning {{shift count is negative}}
+ c = 1 << (unsigned)-1; // expected-warning {{shift count >= width of type}} \
+ // FIXME: 'implicit conversion' warning missing in the new interpreter. \
+ // cxx17-warning {{shift count >= width of type}} \
+ // ref-warning {{shift count >= width of type}} \
+ // ref-warning {{implicit conversion}} \
+ // ref-cxx17-warning {{shift count >= width of type}} \
+ // ref-cxx17-warning {{implicit conversion}}
+ c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}} \
+ // cxx17-warning {{shift count >= width of type}} \
+ // ref-warning {{shift count >= width of type}} \
+ // ref-cxx17-warning {{shift count >= width of type}}
+ c = 1 << c;
+ // FIXME: Enable this.
+#if 0
+ //c <<= 0;
+ //c >>= 0;
+ //c <<= 1;
+ //c >>= 1;
+ //c <<= -1; // expected-warning {{shift count is negative}}
+ //c >>= -1; // expected-warning {{shift count is negative}}
+ //c <<= 999999; // expected-warning {{shift count >= width of type}}
+ //c >>= 999999; // expected-warning {{shift count >= width of type}}
+ //c <<= CHAR_BIT; // expected-warning {{shift count >= width of type}}
+ //c >>= CHAR_BIT; // expected-warning {{shift count >= width of type}}
+ //c <<= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
+ //c >>= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
+#endif
+ (void)((long)c << CHAR_BIT);
+
+ int i; // cxx17-warning {{uninitialized variable}} \
+ // ref-cxx17-warning {{uninitialized variable}}
+ i = 1 << (WORD_BIT - 2);
+ i = 2 << (WORD_BIT - 1); // cxx17-warning {{bits to represent, but 'int' only has}} \
+ // ref-cxx17-warning {{bits to represent, but 'int' only has}}
+ i = 1 << (WORD_BIT - 1); // cxx17-warning-not {{sets the sign bit of the shift expression}}
+ i = -1 << (WORD_BIT - 1); // cxx17-warning {{shifting a negative signed value is undefined}} \
+ // ref-cxx17-warning {{shifting a negative signed value is undefined}}
+ i = -1 << 0; // cxx17-warning {{shifting a negative signed value is undefined}} \
+ // ref-cxx17-warning {{shifting a negative signed value is undefined}}
+ i = 0 << (WORD_BIT - 1);
+ i = (char)1 << (WORD_BIT - 2);
+
+ unsigned u; // cxx17-warning {{uninitialized variable}} \
+ // ref-cxx17-warning {{uninitialized variable}}
+ u = 1U << (WORD_BIT - 1);
+ u = 5U << (WORD_BIT - 1);
+
+ long long int lli; // cxx17-warning {{uninitialized variable}} \
+ // ref-cxx17-warning {{uninitialized variable}}
+ lli = INT_MIN << 2; // cxx17-warning {{shifting a negative signed value is undefined}} \
+ // ref-cxx17-warning {{shifting a negative signed value is undefined}}
+ lli = 1LL << (sizeof(long long) * CHAR_BIT - 2);
+ }
+
+ static_assert(1 << 4 == 16, "");
+ constexpr unsigned m = 2 >> 1;
+ static_assert(m == 1, "");
+ constexpr unsigned char c = 0 << 8;
+ static_assert(c == 0, "");
+ static_assert(true << 1, "");
+ static_assert(1 << (WORD_BIT +1) == 0, ""); // expected-error {{not an integral constant expression}} \
+ // expected-note {{>= width of type 'int'}} \
+ // cxx17-error {{not an integral constant expression}} \
+ // cxx17-note {{>= width of type 'int'}} \
+ // ref-error {{not an integral constant expression}} \
+ // ref-note {{>= width of type 'int'}} \
+ // ref-cxx17-error {{not an integral constant expression}} \
+ // ref-cxx17-note {{>= width of type 'int'}}
+};
Index: clang/lib/AST/Interp/Opcodes.td
===================================================================
--- clang/lib/AST/Interp/Opcodes.td
+++ clang/lib/AST/Interp/Opcodes.td
@@ -433,6 +433,16 @@
def Div : IntegerOpcode;
def Divf : FloatOpcode;
+def Shl : Opcode {
+ let Types = [IntegerTypeClass, IntegerTypeClass];
+ let HasGroup = 1;
+}
+
+def Shr : Opcode {
+ let Types = [IntegerTypeClass, IntegerTypeClass];
+ let HasGroup = 1;
+}
+
def BitAnd : IntegerOpcode;
def BitOr : IntegerOpcode;
def BitXor : IntegerOpcode;
Index: clang/lib/AST/Interp/Interp.h
===================================================================
--- clang/lib/AST/Interp/Interp.h
+++ clang/lib/AST/Interp/Interp.h
@@ -1236,7 +1236,7 @@
if (RHS >= V.bitWidth()) {
S.Stk.push<T>(T::from(0, V.bitWidth()));
} else {
- S.Stk.push<T>(T::from(V >> RHS, V.bitWidth()));
+ S.Stk.push<T>(T::from(static_cast<unsigned>(V) >> RHS, V.bitWidth()));
}
return true;
}
@@ -1251,17 +1251,17 @@
if (V.isNegative()) {
const Expr *E = S.Current->getExpr(OpPC);
S.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << V.toAPSInt();
- } else if (V.countLeadingZeros() < RHS) {
- S.CCEDiag(S.Current->getExpr(OpPC), diag::note_constexpr_lshift_discards);
+ return false;
}
}
- if (V.bitWidth() == 1) {
+ if constexpr (T::bitWidth() == 1) {
S.Stk.push<T>(V);
} else if (RHS >= V.bitWidth()) {
S.Stk.push<T>(T::from(0, V.bitWidth()));
} else {
- S.Stk.push<T>(T::from(V.toUnsigned() << RHS, V.bitWidth()));
+ S.Stk.push<T>(
+ T::from(static_cast<unsigned>(V.toUnsigned()) << RHS, V.bitWidth()));
}
return true;
}
@@ -1272,13 +1272,13 @@
const auto &LHS = S.Stk.pop<typename PrimConv<TL>::T>();
const unsigned Bits = LHS.bitWidth();
- if (RHS.isSigned() && RHS.isNegative()) {
+ if (RHS.isNegative()) {
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.CCEDiag(Loc, diag::note_constexpr_negative_shift) << RHS.toAPSInt();
- return ShiftLeft<TL, TR>(S, OpPC, LHS, Trunc<TR, TL>(S, OpPC, Bits, -RHS));
- } else {
- return ShiftRight<TL, TR>(S, OpPC, LHS, Trunc<TR, TL>(S, OpPC, Bits, RHS));
+ return false;
}
+
+ return ShiftRight<TL, TR>(S, OpPC, LHS, Trunc<TR, TL>(S, OpPC, Bits, RHS));
}
template <PrimType TL, PrimType TR>
@@ -1287,13 +1287,13 @@
const auto &LHS = S.Stk.pop<typename PrimConv<TL>::T>();
const unsigned Bits = LHS.bitWidth();
- if (RHS.isSigned() && RHS.isNegative()) {
+ if (RHS.isNegative()) {
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.CCEDiag(Loc, diag::note_constexpr_negative_shift) << RHS.toAPSInt();
- return ShiftRight<TL, TR>(S, OpPC, LHS, Trunc<TR, TL>(S, OpPC, Bits, -RHS));
- } else {
- return ShiftLeft<TL, TR>(S, OpPC, LHS, Trunc<TR, TL>(S, OpPC, Bits, RHS));
+ return false;
}
+
+ return ShiftLeft<TL, TR>(S, OpPC, LHS, Trunc<TR, TL>(S, OpPC, Bits, RHS));
}
//===----------------------------------------------------------------------===//
Index: clang/lib/AST/Interp/ByteCodeExprGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -294,6 +294,10 @@
return Discard(this->emitBitOr(*T, BO));
case BO_Xor:
return Discard(this->emitBitXor(*T, BO));
+ case BO_Shl:
+ return Discard(this->emitShl(*LT, *RT, BO));
+ case BO_Shr:
+ return Discard(this->emitShr(*LT, *RT, BO));
case BO_LAnd:
case BO_LOr:
default:
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