r292555 - P0426: Make the library implementation of constexpr char_traits a little easier
Hans Wennborg via cfe-commits
cfe-commits at lists.llvm.org
Mon Jan 23 10:07:12 PST 2017
r292807.
Thanks,
Hans
On Thu, Jan 19, 2017 at 5:22 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> Hans, can we get this onto the Clang 4 release branch (along with the
> documentation added in r292558 and fixed in r292559)? This will allow us to
> avoid libc++ carrying a version test for Clang, and allow it to cleanly
> finish off its implementation of P0426.
>
> On 19 January 2017 at 16:45, Richard Smith via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
>>
>> Author: rsmith
>> Date: Thu Jan 19 18:45:35 2017
>> New Revision: 292555
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=292555&view=rev
>> Log:
>> P0426: Make the library implementation of constexpr char_traits a little
>> easier
>> by providing a memchr builtin that returns char* instead of void*.
>>
>> Also add a __has_feature flag to indicate the presence of constexpr forms
>> of
>> the relevant <string> functions.
>>
>> Modified:
>> cfe/trunk/include/clang/Basic/Builtins.def
>> cfe/trunk/lib/AST/ExprConstant.cpp
>> cfe/trunk/lib/CodeGen/CGBuiltin.cpp
>> cfe/trunk/lib/Lex/PPMacroExpansion.cpp
>> cfe/trunk/test/CodeGenCXX/builtins.cpp
>> cfe/trunk/test/Lexer/has_feature_cxx0x.cpp
>> cfe/trunk/test/SemaCXX/constexpr-string.cpp
>>
>> Modified: cfe/trunk/include/clang/Basic/Builtins.def
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Builtins.def?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/Builtins.def (original)
>> +++ cfe/trunk/include/clang/Basic/Builtins.def Thu Jan 19 18:45:35 2017
>> @@ -1339,6 +1339,7 @@ BUILTIN(__builtin_smulll_overflow, "bSLL
>> BUILTIN(__builtin_addressof, "v*v&", "nct")
>> BUILTIN(__builtin_operator_new, "v*z", "c")
>> BUILTIN(__builtin_operator_delete, "vv*", "n")
>> +BUILTIN(__builtin_char_memchr, "c*cC*iz", "n")
>>
>> // Safestack builtins
>> BUILTIN(__builtin___get_unsafe_stack_start, "v*", "Fn")
>>
>> Modified: cfe/trunk/lib/AST/ExprConstant.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)
>> +++ cfe/trunk/lib/AST/ExprConstant.cpp Thu Jan 19 18:45:35 2017
>> @@ -5683,6 +5683,7 @@ bool PointerExprEvaluator::VisitBuiltinC
>> case Builtin::BI__builtin_strchr:
>> case Builtin::BI__builtin_wcschr:
>> case Builtin::BI__builtin_memchr:
>> + case Builtin::BI__builtin_char_memchr:
>> case Builtin::BI__builtin_wmemchr: {
>> if (!Visit(E->getArg(0)))
>> return false;
>> @@ -5720,6 +5721,7 @@ bool PointerExprEvaluator::VisitBuiltinC
>> // Fall through.
>> case Builtin::BImemchr:
>> case Builtin::BI__builtin_memchr:
>> + case Builtin::BI__builtin_char_memchr:
>> // memchr compares by converting both sides to unsigned char.
>> That's also
>> // correct for strchr if we get this far (to cope with plain char
>> being
>> // unsigned in the strchr case).
>>
>> Modified: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBuiltin.cpp?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/CodeGen/CGBuiltin.cpp (original)
>> +++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp Thu Jan 19 18:45:35 2017
>> @@ -1189,6 +1189,10 @@ RValue CodeGenFunction::EmitBuiltinExpr(
>> return RValue::get(Dest.getPointer());
>> }
>>
>> + case Builtin::BI__builtin_char_memchr:
>> + BuiltinID = Builtin::BI__builtin_memchr;
>> + break;
>> +
>> case Builtin::BI__builtin___memcpy_chk: {
>> // fold __builtin_memcpy_chk(x, y, cst1, cst2) to memcpy iff
>> cst1<=cst2.
>> llvm::APSInt Size, DstSize;
>>
>> Modified: cfe/trunk/lib/Lex/PPMacroExpansion.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/PPMacroExpansion.cpp?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Lex/PPMacroExpansion.cpp (original)
>> +++ cfe/trunk/lib/Lex/PPMacroExpansion.cpp Thu Jan 19 18:45:35 2017
>> @@ -1183,6 +1183,7 @@ static bool HasFeature(const Preprocesso
>> .Case("cxx_attributes", LangOpts.CPlusPlus11)
>> .Case("cxx_auto_type", LangOpts.CPlusPlus11)
>> .Case("cxx_constexpr", LangOpts.CPlusPlus11)
>> + .Case("cxx_constexpr_string_builtins", LangOpts.CPlusPlus11)
>> .Case("cxx_decltype", LangOpts.CPlusPlus11)
>> .Case("cxx_decltype_incomplete_return_types", LangOpts.CPlusPlus11)
>> .Case("cxx_default_function_template_args", LangOpts.CPlusPlus11)
>>
>> Modified: cfe/trunk/test/CodeGenCXX/builtins.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/builtins.cpp?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/CodeGenCXX/builtins.cpp (original)
>> +++ cfe/trunk/test/CodeGenCXX/builtins.cpp Thu Jan 19 18:45:35 2017
>> @@ -26,3 +26,7 @@ int x = __builtin_abs(-2);
>> long y = __builtin_abs(-2l);
>> // CHECK: [[Y:%.+]] = call i64 @_Z13__builtin_absl(i64 -2)
>> // CHECK: store i64 [[Y]], i64* @y, align 8
>> +
>> +extern const char char_memchr_arg[32];
>> +char *memchr_result = __builtin_char_memchr(char_memchr_arg, 123, 32);
>> +// CHECK: call i8* @memchr(i8* getelementptr inbounds ([32 x i8], [32 x
>> i8]* @char_memchr_arg, i32 0, i32 0), i32 123, i64 32)
>>
>> Modified: cfe/trunk/test/Lexer/has_feature_cxx0x.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Lexer/has_feature_cxx0x.cpp?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Lexer/has_feature_cxx0x.cpp (original)
>> +++ cfe/trunk/test/Lexer/has_feature_cxx0x.cpp Thu Jan 19 18:45:35 2017
>> @@ -301,6 +301,17 @@ int no_constexpr();
>> // CHECK-11: has_constexpr
>> // CHECK-NO-11: no_constexpr
>>
>> +#if __has_feature(cxx_constexpr_string_builtins)
>> +int has_constexpr_string_builtins();
>> +#else
>> +int no_constexpr_string_builtins();
>> +#endif
>> +
>> +// CHECK-1Z: has_constexpr_string_builtins
>> +// CHECK-14: has_constexpr_string_builtins
>> +// CHECK-11: has_constexpr_string_builtins
>> +// CHECK-NO-11: no_constexpr_string_builtins
>> +
>> #if __has_feature(cxx_generalized_initializers)
>> int has_generalized_initializers();
>> #else
>>
>> Modified: cfe/trunk/test/SemaCXX/constexpr-string.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constexpr-string.cpp?rev=292555&r1=292554&r2=292555&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/constexpr-string.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/constexpr-string.cpp Thu Jan 19 18:45:35 2017
>> @@ -166,6 +166,27 @@ namespace StrchrEtc {
>> static_assert(__builtin_memchr(nullptr, 'x', 3) == nullptr); //
>> expected-error {{not an integral constant}} expected-note {{dereferenced
>> null}}
>> static_assert(__builtin_memchr(nullptr, 'x', 0) == nullptr); // FIXME:
>> Should we reject this?
>>
>> + static_assert(__builtin_char_memchr(kStr, 'a', 0) == nullptr);
>> + static_assert(__builtin_char_memchr(kStr, 'a', 1) == kStr);
>> + static_assert(__builtin_char_memchr(kStr, '\0', 5) == nullptr);
>> + static_assert(__builtin_char_memchr(kStr, '\0', 6) == kStr + 5);
>> + static_assert(__builtin_char_memchr(kStr, '\xff', 8) == kStr + 4);
>> + static_assert(__builtin_char_memchr(kStr, '\xff' + 256, 8) == kStr +
>> 4);
>> + static_assert(__builtin_char_memchr(kStr, '\xff' - 256, 8) == kStr +
>> 4);
>> + static_assert(__builtin_char_memchr(kFoo, 'x', 3) == nullptr);
>> + static_assert(__builtin_char_memchr(kFoo, 'x', 4) == nullptr); //
>> expected-error {{not an integral constant}} expected-note {{dereferenced
>> one-past-the-end}}
>> + static_assert(__builtin_char_memchr(nullptr, 'x', 3) == nullptr); //
>> expected-error {{not an integral constant}} expected-note {{dereferenced
>> null}}
>> + static_assert(__builtin_char_memchr(nullptr, 'x', 0) == nullptr); //
>> FIXME: Should we reject this?
>> +
>> + static_assert(*__builtin_char_memchr(kStr, '\xff', 8) == '\xff');
>> + constexpr bool char_memchr_mutable() {
>> + char buffer[] = "mutable";
>> + *__builtin_char_memchr(buffer, 't', 8) = 'r';
>> + *__builtin_char_memchr(buffer, 'm', 8) = 'd';
>> + return __builtin_strcmp(buffer, "durable") == 0;
>> + }
>> + static_assert(char_memchr_mutable());
>> +
>> constexpr bool a = !strchr("hello", 'h'); // expected-error {{constant
>> expression}} expected-note {{non-constexpr function 'strchr' cannot be used
>> in a constant expression}}
>> constexpr bool b = !memchr("hello", 'h', 3); // expected-error
>> {{constant expression}} expected-note {{non-constexpr function 'memchr'
>> cannot be used in a constant expression}}
>> }
>>
>>
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