// AsmJit - Machine code generation for C++ // // * Official AsmJit Home Page: https://asmjit.com // * Official Github Repository: https://github.com/asmjit/asmjit // // Copyright (c) 2008-2020 The AsmJit Authors // // This software is provided 'as-is', without any express or implied // warranty. In no event will the authors be held liable for any damages // arising from the use of this software. // // Permission is granted to anyone to use this software for any purpose, // including commercial applications, and to alter it and redistribute it // freely, subject to the following restrictions: // // 1. The origin of this software must not be misrepresented; you must not // claim that you wrote the original software. If you use this software // in a product, an acknowledgment in the product documentation would be // appreciated but is not required. // 2. Altered source versions must be plainly marked as such, and must not be // misrepresented as being the original software. // 3. This notice may not be removed or altered from any source distribution. #ifndef ASMJIT_X86_X86BUILDER_H_INCLUDED #define ASMJIT_X86_X86BUILDER_H_INCLUDED #include "../core/api-config.h" #ifndef ASMJIT_NO_BUILDER #include "../core/builder.h" #include "../core/datatypes.h" #include "../x86/x86emitter.h" ASMJIT_BEGIN_SUB_NAMESPACE(x86) //! \addtogroup asmjit_x86 //! \{ // ============================================================================ // [asmjit::x86::Builder] // ============================================================================ //! X86/X64 builder implementation. //! //! The code representation used by \ref BaseBuilder is compatible with everything //! AsmJit provides. Each instruction is stored as \ref InstNode, which contains //! instruction id, options, and operands. Each instruction emitted will create //! a new \ref InstNode instance and add it to the current cursor in the double-linked //! list of nodes. Since the instruction stream used by \ref BaseBuilder can be //! manipulated, we can rewrite the SumInts example from \ref asmjit_assembler //! into the following: //! //! ``` //! #include //! #include //! //! using namespace asmjit; //! //! typedef void (*SumIntsFunc)(int* dst, const int* a, const int* b); //! //! // Small helper function to print the current content of `cb`. //! static void dumpCode(BaseBuilder& builder, const char* phase) { //! String sb; //! builder.dump(sb); //! printf("%s:\n%s\n", phase, sb.data()); //! } //! //! int main() { //! JitRuntime rt; // Create JIT Runtime. //! CodeHolder code; // Create a CodeHolder. //! //! code.init(rt.environment()); // Initialize code to match the JIT environment. //! x86::Builder cb(&code); // Create and attach x86::Builder to `code`. //! //! // Decide which registers will be mapped to function arguments. Try changing //! // registers of `dst`, `srcA`, and `srcB` and see what happens in function's //! // prolog and epilog. //! x86::Gp dst = cb.zax(); //! x86::Gp srcA = cb.zcx(); //! x86::Gp srcB = cb.zdx(); //! //! X86::Xmm vec0 = x86::xmm0; //! X86::Xmm vec1 = x86::xmm1; //! //! // Create and initialize `FuncDetail`. //! FuncDetail func; //! func.init(FuncSignatureT(CallConv::kIdHost)); //! //! // Remember prolog insertion point. //! BaseNode* prologInsertionPoint = cb.cursor(); //! //! // Emit function body: //! cb.movdqu(vec0, x86::ptr(srcA)); // Load 4 ints from [srcA] to XMM0. //! cb.movdqu(vec1, x86::ptr(srcB)); // Load 4 ints from [srcB] to XMM1. //! cb.paddd(vec0, vec1); // Add 4 ints in XMM1 to XMM0. //! cb.movdqu(x86::ptr(dst), vec0); // Store the result to [dst]. //! //! // Remember epilog insertion point. //! BaseNode* epilogInsertionPoint = cb.cursor(); //! //! // Let's see what we have now. //! dumpCode(cb, "Raw Function"); //! //! // Now, after we emitted the function body, we can insert the prolog, arguments //! // allocation, and epilog. This is not possible with using pure x86::Assembler. //! FuncFrame frame; //! frame.init(func); //! //! // Make XMM0 and XMM1 dirty; `kGroupVec` describes XMM|YMM|ZMM registers. //! frame.setDirtyRegs(x86::Reg::kGroupVec, IntUtils::mask(0, 1)); //! //! FuncArgsAssignment args(&func); // Create arguments assignment context. //! args.assignAll(dst, srcA, srcB); // Assign our registers to arguments. //! args.updateFrame(frame); // Reflect our args in FuncFrame. //! frame.finalize(); // Finalize the FuncFrame (updates it). //! //! // Insert function prolog and allocate arguments to registers. //! cb.setCursor(prologInsertionPoint); //! cb.emitProlog(frame); //! cb.emitArgsAssignment(frame, args); //! //! // Insert function epilog. //! cb.setCursor(epilogInsertionPoint); //! cb.emitEpilog(frame); //! //! // Let's see how the function's prolog and epilog looks. //! dumpCode(cb, "Prolog & Epilog"); //! //! // IMPORTANT: Builder requires finalize() to be called to serialize its //! // code to the Assembler (it automatically creates one if not attached). //! cb.finalize(); //! //! SumIntsFunc fn; //! Error err = rt.add(&fn, &code); // Add the generated code to the runtime. //! if (err) return 1; // Handle a possible error case. //! //! // Execute the generated function. //! int inA[4] = { 4, 3, 2, 1 }; //! int inB[4] = { 1, 5, 2, 8 }; //! int out[4]; //! fn(out, inA, inB); //! //! // Prints {5 8 4 9} //! printf("{%d %d %d %d}\n", out[0], out[1], out[2], out[3]); //! //! rt.release(fn); // Explicitly remove the function from the runtime. //! return 0; //! } //! ``` //! //! When the example is executed it should output the following (this one using //! AMD64-SystemV ABI): //! //! ``` //! Raw Function: //! movdqu xmm0, [rcx] //! movdqu xmm1, [rdx] //! paddd xmm0, xmm1 //! movdqu [rax], xmm0 //! //! Prolog & Epilog: //! mov rax, rdi //! mov rcx, rsi //! movdqu xmm0, [rcx] //! movdqu xmm1, [rdx] //! paddd xmm0, xmm1 //! movdqu [rax], xmm0 //! ret //! //! {5 8 4 9} //! ``` //! //! The number of use-cases of \ref BaseBuilder is not limited and highly depends //! on your creativity and experience. The previous example can be easily improved //! to collect all dirty registers inside the function programmatically and to pass //! them to \ref FuncFrame::setDirtyRegs(). //! //! ``` //! #include //! //! using namespace asmjit; //! //! // NOTE: This function doesn't cover all possible constructs. It ignores //! // instructions that write to implicit registers that are not part of the //! // operand list. It also counts read-only registers. Real implementation //! // would be a bit more complicated, but still relatively easy to implement. //! static void collectDirtyRegs(const BaseNode* first, //! const BaseNode* last, //! uint32_t regMask[BaseReg::kGroupVirt]) { //! const BaseNode* node = first; //! while (node) { //! if (node->actsAsInst()) { //! const InstNode* inst = node->as(); //! const Operand* opArray = inst->operands(); //! //! for (uint32_t i = 0, opCount = inst->opCount(); i < opCount; i++) { //! const Operand& op = opArray[i]; //! if (op.isReg()) { //! const x86::Reg& reg = op.as(); //! if (reg.group() < BaseReg::kGroupVirt) { //! regMask[reg.group()] |= 1u << reg.id(); //! } //! } //! } //! } //! //! if (node == last) //! break; //! node = node->next(); //! } //! } //! //! static void setDirtyRegsOfFuncFrame(const x86::Builder& builder, FuncFrame& frame) { //! uint32_t regMask[BaseReg::kGroupVirt] {}; //! collectDirtyRegs(builder.firstNode(), builder.lastNode(), regMask); //! //! // X86/X64 ABIs only require to save GP/XMM registers: //! frame.setDirtyRegs(x86::Reg::kGroupGp , regMask[x86::Reg::kGroupGp ]); //! frame.setDirtyRegs(x86::Reg::kGroupVec, regMask[x86::Reg::kGroupVec]); //! } //! ``` //! //! ### Casting Between Various Emitters //! //! Even when \ref BaseAssembler and \ref BaseBuilder provide the same interface //! as defined by \ref BaseEmitter their platform dependent variants like \ref //! x86::Assembler and \ref x86::Builder cannot be interchanged or casted //! to each other by using a C++ `static_cast<>`. The main reason is the //! inheritance graph of these classes is different and cast-incompatible, as //! illustrated below: //! //! ``` //! +--------------+ +=========================+ //! +----------------------->| x86::Emitter |<--+--# x86::EmitterImplicitT<> #<--+ //! | +--------------+ | +=========================+ | //! | (abstract) | (mixin) | //! | +--------------+ +~~~~~~~~~~~~~~+ | | //! +-->| BaseAssembler|---->|x86::Assembler|<--+ | //! | +--------------+ +~~~~~~~~~~~~~~+ | | //! | (abstract) (final) | | //! +===============+ | +--------------+ +~~~~~~~~~~~~~~+ | | //! # BaseEmitter #--+-->| BaseBuilder |--+->| x86::Builder |<--+ | //! +===============+ +--------------+ | +~~~~~~~~~~~~~~+ | //! (abstract) (abstract) | (final) | //! +---------------------+ | //! | | //! | +--------------+ +~~~~~~~~~~~~~~+ +=========================+ | //! +-->| BaseCompiler |---->| x86::Compiler|<-----# x86::EmitterExplicitT<> #---+ //! +--------------+ +~~~~~~~~~~~~~~+ +=========================+ //! (abstract) (final) (mixin) //! ``` //! //! The graph basically shows that it's not possible to cast between \ref //! x86::Assembler and \ref x86::Builder. However, since both share the //! base interface (\ref BaseEmitter) it's possible to cast them to a class //! that cannot be instantiated, but defines the same interface - the class //! is called \ref x86::Emitter and was introduced to make it possible to //! write a function that can emit to both \ref x86::Assembler and \ref //! x86::Builder. Note that \ref x86::Emitter cannot be created, it's abstract //! and has private constructors and destructors; it was only designed to be //! casted to and used as an interface. //! //! Each architecture-specific emitter implements a member function called //! `as()`, which casts the instance to the architecture //! specific emitter as illustrated below: //! //! ``` //! #include //! //! using namespace asmjit; //! //! static void emitSomething(x86::Emitter* e) { //! e->mov(x86::eax, x86::ebx); //! } //! //! static void assemble(CodeHolder& code, bool useAsm) { //! if (useAsm) { //! x86::Assembler assembler(&code); //! emitSomething(assembler.as()); //! } //! else { //! x86::Builder builder(&code); //! emitSomething(builder.as()); //! //! // NOTE: Builder requires `finalize()` to be called to serialize its //! // content to Assembler (it automatically creates one if not attached). //! builder.finalize(); //! } //! } //! ``` //! //! The example above shows how to create a function that can emit code to //! either \ref x86::Assembler or \ref x86::Builder through \ref x86::Emitter, //! which provides emitter-neutral functionality. \ref x86::Emitter, however, //! doesn't provide any emitter-specific functionality like `setCursor()`. //! //! ### Code Injection and Manipulation //! //! \ref BaseBuilder emitter stores its nodes in a double-linked list, which //! makes it easy to manipulate that list during the code generation or //! afterwards. Each node is always emitted next to the current cursor and the //! cursor is advanced to that newly emitted node. The cursor can be retrieved //! and changed by \ref BaseBuilder::cursor() and \ref BaseBuilder::setCursor(), //! respectively. //! //! The example below demonstrates how to remember a node and inject something //! next to it. //! //! ``` //! static void example(x86::Builder& builder) { //! // Emit something, after it returns the cursor would point at the last //! // emitted node. //! builder.mov(x86::rax, x86::rdx); // [1] //! //! // We can retrieve the node. //! BaseNode* node = builder.cursor(); //! //! // Change the instruction we just emitted, just for fun... //! if (node->isInst()) { //! InstNode* inst = node->as(); //! // Changes the operands at index [1] to RCX. //! inst->setOp(1, x86::rcx); //! } //! //! // ------------------------- Generate Some Code ------------------------- //! builder.add(x86::rax, x86::rdx); // [2] //! builder.shr(x86::rax, 3); // [3] //! // ---------------------------------------------------------------------- //! //! // Now, we know where our node is, and we can simply change the cursor //! // and start emitting something after it. The setCursor() function //! // returns the previous cursor, and it's always a good practice to remember //! // it, because you never know if you are not already injecting the code //! // somewhere else... //! BaseNode* oldCursor = builder.setCursor(node); //! //! builder.mul(x86::rax, 8); // [4] //! //! // Restore the cursor //! builder.setCursor(oldCursor); //! } //! ``` //! //! The function above would actually emit the following: //! //! ``` //! mov rax, rcx ; [1] Patched at the beginning. //! mul rax, 8 ; [4] Injected. //! add rax, rdx ; [2] Followed [1] initially. //! shr rax, 3 ; [3] Follows [2]. //! ``` class ASMJIT_VIRTAPI Builder : public BaseBuilder, public EmitterImplicitT { public: ASMJIT_NONCOPYABLE(Builder) typedef BaseBuilder Base; //! \name Construction & Destruction //! \{ ASMJIT_API explicit Builder(CodeHolder* code = nullptr) noexcept; ASMJIT_API virtual ~Builder() noexcept; //! \} //! \name Finalize //! \{ ASMJIT_API Error finalize() override; //! \} //! \name Events //! \{ ASMJIT_API Error onAttach(CodeHolder* code) noexcept override; //! \} }; //! \} ASMJIT_END_SUB_NAMESPACE #endif // !ASMJIT_NO_BUILDER #endif // ASMJIT_X86_X86BUILDER_H_INCLUDED