tbaeder created this revision.
tbaeder added reviewers: aaron.ballman, erichkeane, shafik, cor3ntin.
Herald added a project: All.
tbaeder requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
One existing problem is that we can't do much with the values since comparing
with nans is broken ATM and I don't want to make this patch depend on the
`__builtin_bit_cast` patch.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D155356
Files:
clang/lib/AST/Interp/InterpBuiltin.cpp
clang/test/AST/Interp/builtin-functions.cpp
Index: clang/test/AST/Interp/builtin-functions.cpp
===================================================================
--- clang/test/AST/Interp/builtin-functions.cpp
+++ clang/test/AST/Interp/builtin-functions.cpp
@@ -1,5 +1,8 @@
// RUN: %clang_cc1 -fexperimental-new-constant-interpreter %s -verify
// RUN: %clang_cc1 -verify=ref %s -Wno-constant-evaluated
+// RUN: %clang_cc1 -std=c++20 -fexperimental-new-constant-interpreter %s -verify
+// RUN: %clang_cc1 -std=c++20 -verify=ref %s -Wno-constant-evaluated
+
namespace strcmp {
constexpr char kFoobar[6] = {'f','o','o','b','a','r'};
@@ -34,3 +37,28 @@
// ref-error {{not an integral constant}} \
// ref-note {{dereferenced one-past-the-end}}
}
+
+namespace nan {
+ constexpr double NaN1 = __builtin_nan("");
+
+#if __cplusplus >= 202002
+ /// Reading an uninitialized value as part of the argument.
+ constexpr int foo() { // ref-error {{never produces a constant expression}}
+ char f[2];
+ f[0] = '1';
+
+ double d = __builtin_nan(f); // ref-note 2{{subexpression not valid in a constant expression}} \
+ // expected-note {{read of uninitialized object}} \
+ // expected-note {{in call to '__builtin_nan}}
+ return 1;
+ }
+ static_assert(foo() == 1); // ref-error {{not an integral constant expression}} \
+ // ref-note {{in call to}} \
+ // expected-error {{not an integral constant expression}} \
+ // expected-note {{in call to}}
+#endif
+
+
+ constexpr float Nan2 = __builtin_nans([](){return "0xAE98";}()); // ref-error {{must be initialized by a constant expression}}
+
+}
Index: clang/lib/AST/Interp/InterpBuiltin.cpp
===================================================================
--- clang/lib/AST/Interp/InterpBuiltin.cpp
+++ clang/lib/AST/Interp/InterpBuiltin.cpp
@@ -9,6 +9,7 @@
#include "Interp.h"
#include "PrimType.h"
#include "clang/Basic/Builtins.h"
+#include "clang/Basic/TargetInfo.h"
namespace clang {
namespace interp {
@@ -57,6 +58,63 @@
return true;
}
+static bool interp__builtin_nan(InterpState &S, CodePtr OpPC,
+ const InterpFrame *Frame, const Function *F,
+ bool Signaling) {
+ const Pointer &Arg = getParam<Pointer>(Frame, 0);
+
+ if (!CheckLoad(S, OpPC, Arg))
+ return false;
+
+ assert(Arg.getFieldDesc()->isPrimitiveArray());
+
+ llvm::APInt Fill;
+ if (Arg.getNumElems() == 0)
+ Fill = llvm::APInt(32, 0);
+ else {
+ // Convert the given string to an integer using StringRef's API.
+ std::string Str;
+
+ for (unsigned I = 0, E = Arg.getNumElems(); I != E; ++I) {
+ const Pointer &Elem = Arg.atIndex(I);
+
+ if (!CheckLoad(S, OpPC, Elem))
+ return false;
+
+ Str += Elem.deref<char>();
+ }
+ StringRef(Str).getAsInteger(0, Fill);
+ }
+
+ const llvm::fltSemantics &TargetSemantics =
+ S.getCtx().getFloatTypeSemantics(F->getDecl()->getReturnType());
+
+ Floating Result;
+ if (S.getCtx().getTargetInfo().isNan2008()) {
+ if (Signaling)
+ Result = Floating(
+ llvm::APFloat::getSNaN(TargetSemantics, /*Negative=*/false, &Fill));
+ else
+ Result = Floating(
+ llvm::APFloat::getQNaN(TargetSemantics, /*Negative=*/false, &Fill));
+ } else {
+ // Prior to IEEE 754-2008, architectures were allowed to choose whether
+ // the first bit of their significand was set for qNaN or sNaN. MIPS chose
+ // a different encoding to what became a standard in 2008, and for pre-
+ // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
+ // sNaN. This is now known as "legacy NaN" encoding.
+ if (Signaling)
+ Result = Floating(
+ llvm::APFloat::getQNaN(TargetSemantics, /*Negative=*/false, &Fill));
+ else
+ Result = Floating(
+ llvm::APFloat::getSNaN(TargetSemantics, /*Negative=*/false, &Fill));
+ }
+
+ S.Stk.push<Floating>(Result);
+ return true;
+}
+
bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F) {
InterpFrame *Frame = S.Current;
APValue Dummy;
@@ -70,7 +128,24 @@
case Builtin::BI__builtin_strcmp:
if (interp__builtin_strcmp(S, OpPC, Frame))
return Ret<PT_Sint32>(S, OpPC, Dummy);
- return false;
+ break;
+ case Builtin::BI__builtin_nan:
+ case Builtin::BI__builtin_nanf:
+ case Builtin::BI__builtin_nanl:
+ case Builtin::BI__builtin_nanf16:
+ case Builtin::BI__builtin_nanf128:
+ if (interp__builtin_nan(S, OpPC, Frame, F, /*Signaling=*/false))
+ return Ret<PT_Float>(S, OpPC, Dummy);
+ break;
+ case Builtin::BI__builtin_nans:
+ case Builtin::BI__builtin_nansf:
+ case Builtin::BI__builtin_nansl:
+ case Builtin::BI__builtin_nansf16:
+ case Builtin::BI__builtin_nansf128:
+ if (interp__builtin_nan(S, OpPC, Frame, F, /*Signaling=*/true))
+ return Ret<PT_Float>(S, OpPC, Dummy);
+ break;
+
default:
return false;
}
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