Shafik, Zachary, I think you reported this a bit ago, but now I got around to fix it (also because it was breaking something real).
Thanks, -- Davide On Tue, Feb 5, 2019 at 9:30 AM Davide Italiano via lldb-commits <lldb-commits@lists.llvm.org> wrote: > > Author: davide > Date: Tue Feb 5 09:30:53 2019 > New Revision: 353191 > > URL: http://llvm.org/viewvc/llvm-project?rev=353191&view=rev > Log: > [Obj-C] Fix undefined behaviour(s) in the new NSTaggedDate formatter. > > Type punning through a union -> no good. > double to uint64 to double again -> no good either. > > The nice side effect, other than silencing the sanitizer bot > is that it fixes the formatting of some dates, e.g. Jan 1st 1970. > > <rdar://problem/47617983> > > Modified: > lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp > > Modified: lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp > URL: > http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp?rev=353191&r1=353190&r2=353191&view=diff > ============================================================================== > --- lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp (original) > +++ lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp Tue Feb 5 09:30:53 2019 > @@ -27,6 +27,7 @@ > #include "lldb/Utility/Stream.h" > > #include "llvm/ADT/APInt.h" > +#include "llvm/ADT/bit.h" > > #include "Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.h" > > @@ -749,24 +750,18 @@ bool lldb_private::formatters::NSURLSumm > /// distantFuture, except within about 1e-25 second of the reference date. > const int TAGGED_DATE_EXPONENT_BIAS = 0x3ef; > > -typedef union { > - struct { > - uint64_t fraction:52; // unsigned > - uint64_t exponent:11; // signed > - uint64_t sign:1; > - } repr; > - uint64_t i; > - double d; > -} DoubleBits; > -typedef union { > - struct { > - uint64_t fraction:52; // unsigned > - uint64_t exponent:7; // signed > - uint64_t sign:1; > - uint64_t unused:4; // placeholder for pointer tag bits > - } repr; > - uint64_t i; > -} TaggedDoubleBits; > +struct DoubleBits { > + uint64_t fraction : 52; // unsigned > + uint64_t exponent : 11; // signed > + uint64_t sign : 1; > +}; > + > +struct TaggedDoubleBits { > + uint64_t fraction : 52; // unsigned > + uint64_t exponent : 7; // signed > + uint64_t sign : 1; > + uint64_t unused : 4; // placeholder for pointer tag bits > +}; > > static uint64_t decodeExponent(uint64_t exp) { > // Tagged exponent field is 7-bit signed. Sign-extend the value to 64 bits > @@ -774,24 +769,24 @@ static uint64_t decodeExponent(uint64_t > return llvm::SignExtend64<7>(exp) + TAGGED_DATE_EXPONENT_BIAS; > } > > -static uint64_t decodeTaggedTimeInterval(uint64_t encodedTimeInterval) { > +static double decodeTaggedTimeInterval(uint64_t encodedTimeInterval) { > if (encodedTimeInterval == 0) > return 0.0; > if (encodedTimeInterval == std::numeric_limits<uint64_t>::max()) > return (uint64_t)-0.0; > > - TaggedDoubleBits encodedBits = {}; > - encodedBits.i = encodedTimeInterval; > - DoubleBits decodedBits; > + TaggedDoubleBits encodedBits = > + llvm::bit_cast<TaggedDoubleBits>(encodedTimeInterval); > + assert(encodedBits.unused == 0); > > // Sign and fraction are represented exactly. > // Exponent is encoded. > - assert(encodedBits.repr.unused == 0); > - decodedBits.repr.sign = encodedBits.repr.sign; > - decodedBits.repr.fraction = encodedBits.repr.fraction; > - decodedBits.repr.exponent = decodeExponent(encodedBits.repr.exponent); > + DoubleBits decodedBits; > + decodedBits.sign = encodedBits.sign; > + decodedBits.fraction = encodedBits.fraction; > + decodedBits.exponent = decodeExponent(encodedBits.exponent); > > - return decodedBits.d; > + return llvm::bit_cast<double>(decodedBits); > } > > bool lldb_private::formatters::NSDateSummaryProvider( > @@ -868,7 +863,8 @@ bool lldb_private::formatters::NSDateSum > > // Accomodate for the __NSTaggedDate format introduced in Foundation 1600. > if (class_name == g___NSTaggedDate) { > - auto *runtime = > llvm::dyn_cast_or_null<AppleObjCRuntime>(process_sp->GetObjCLanguageRuntime()); > + auto *runtime = llvm::dyn_cast_or_null<AppleObjCRuntime>( > + process_sp->GetObjCLanguageRuntime()); > if (runtime && runtime->GetFoundationVersion() >= 1600) > date_value = decodeTaggedTimeInterval(value_bits << 4); > } > > > _______________________________________________ > lldb-commits mailing list > lldb-commits@lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
