From eee944e7f9e60df44714eb547d0b876ee5dc7290 Mon Sep 17 00:00:00 2001 From: Erik Pilkington Date: Tue, 2 Jul 2019 18:28:13 +0000 Subject: [C++2a] Add __builtin_bit_cast, used to implement std::bit_cast This commit adds a new builtin, __builtin_bit_cast(T, v), which performs a bit_cast from a value v to a type T. This expression can be evaluated at compile time under specific circumstances. The compile time evaluation currently doesn't support bit-fields, but I'm planning on fixing this in a follow up (some of the logic for figuring this out is in CodeGen). I'm also planning follow-ups for supporting some more esoteric types that the constexpr evaluator supports, as well as extending __builtin_memcpy constexpr evaluation to use the same infrastructure. rdar://44987528 Differential revision: https://reviews.llvm.org/D62825 llvm-svn: 364954 --- llvm/lib/ExecutionEngine/ExecutionEngine.cpp | 53 ---------------------------- 1 file changed, 53 deletions(-) (limited to 'llvm/lib/ExecutionEngine') diff --git a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp index c2ea0f07f85..1c6c0406d04 100644 --- a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp +++ b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp @@ -1019,32 +1019,6 @@ GenericValue ExecutionEngine::getConstantValue(const Constant *C) { return Result; } -/// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst -/// with the integer held in IntVal. -static void StoreIntToMemory(const APInt &IntVal, uint8_t *Dst, - unsigned StoreBytes) { - assert((IntVal.getBitWidth()+7)/8 >= StoreBytes && "Integer too small!"); - const uint8_t *Src = (const uint8_t *)IntVal.getRawData(); - - if (sys::IsLittleEndianHost) { - // Little-endian host - the source is ordered from LSB to MSB. Order the - // destination from LSB to MSB: Do a straight copy. - memcpy(Dst, Src, StoreBytes); - } else { - // Big-endian host - the source is an array of 64 bit words ordered from - // LSW to MSW. Each word is ordered from MSB to LSB. Order the destination - // from MSB to LSB: Reverse the word order, but not the bytes in a word. - while (StoreBytes > sizeof(uint64_t)) { - StoreBytes -= sizeof(uint64_t); - // May not be aligned so use memcpy. - memcpy(Dst + StoreBytes, Src, sizeof(uint64_t)); - Src += sizeof(uint64_t); - } - - memcpy(Dst, Src + sizeof(uint64_t) - StoreBytes, StoreBytes); - } -} - void ExecutionEngine::StoreValueToMemory(const GenericValue &Val, GenericValue *Ptr, Type *Ty) { const unsigned StoreBytes = getDataLayout().getTypeStoreSize(Ty); @@ -1092,33 +1066,6 @@ void ExecutionEngine::StoreValueToMemory(const GenericValue &Val, std::reverse((uint8_t*)Ptr, StoreBytes + (uint8_t*)Ptr); } -/// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting -/// from Src into IntVal, which is assumed to be wide enough and to hold zero. -static void LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes) { - assert((IntVal.getBitWidth()+7)/8 >= LoadBytes && "Integer too small!"); - uint8_t *Dst = reinterpret_cast( - const_cast(IntVal.getRawData())); - - if (sys::IsLittleEndianHost) - // Little-endian host - the destination must be ordered from LSB to MSB. - // The source is ordered from LSB to MSB: Do a straight copy. - memcpy(Dst, Src, LoadBytes); - else { - // Big-endian - the destination is an array of 64 bit words ordered from - // LSW to MSW. Each word must be ordered from MSB to LSB. The source is - // ordered from MSB to LSB: Reverse the word order, but not the bytes in - // a word. - while (LoadBytes > sizeof(uint64_t)) { - LoadBytes -= sizeof(uint64_t); - // May not be aligned so use memcpy. - memcpy(Dst, Src + LoadBytes, sizeof(uint64_t)); - Dst += sizeof(uint64_t); - } - - memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes); - } -} - /// FIXME: document /// void ExecutionEngine::LoadValueFromMemory(GenericValue &Result, -- cgit v1.2.3