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ea03e10fac
Microoptimize Twine's with unsigned and int to not pin their value to
the stack. This saves stack space in common cases and allows mem2reg
in the caller. A simple example is:
void foo(const Twine &);
void bar(int x) {
foo("xyz: " + Twine(x));
}
Before:
__Z3bari:
subq $40, %rsp
movl %edi, 36(%rsp)
leaq L_.str3(%rip), %rax
leaq 36(%rsp), %rcx
leaq 8(%rsp), %rdi
movq %rax, 8(%rsp)
movq %rcx, 16(%rsp)
movb $3, 24(%rsp)
movb $7, 25(%rsp)
callq __Z3fooRKN4llvm5TwineE
addq $40, %rsp
ret
After:
__Z3bari:
subq $24, %rsp
leaq L_.str3(%rip), %rax
movq %rax, (%rsp)
movslq %edi, %rax
movq %rax, 8(%rsp)
movb $3, 16(%rsp)
movb $7, 17(%rsp)
leaq (%rsp), %rdi
callq __Z3fooRKN4llvm5TwineE
addq $24, %rsp
ret
It saves 16 bytes of stack and one instruction in this case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103107 91177308-0d34-0410-b5e6-96231b3b80d8
141 lines
3.7 KiB
C++
141 lines
3.7 KiB
C++
//===-- Twine.cpp - Fast Temporary String Concatenation -------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/Twine.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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std::string Twine::str() const {
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SmallString<256> Vec;
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return toStringRef(Vec).str();
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}
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void Twine::toVector(SmallVectorImpl<char> &Out) const {
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raw_svector_ostream OS(Out);
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print(OS);
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}
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StringRef Twine::toStringRef(SmallVectorImpl<char> &Out) const {
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if (isSingleStringRef())
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return getSingleStringRef();
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toVector(Out);
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return StringRef(Out.data(), Out.size());
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}
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void Twine::printOneChild(raw_ostream &OS, const void *Ptr,
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NodeKind Kind) const {
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switch (Kind) {
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case Twine::NullKind: break;
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case Twine::EmptyKind: break;
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case Twine::TwineKind:
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static_cast<const Twine*>(Ptr)->print(OS);
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break;
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case Twine::CStringKind:
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OS << static_cast<const char*>(Ptr);
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break;
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case Twine::StdStringKind:
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OS << *static_cast<const std::string*>(Ptr);
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break;
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case Twine::StringRefKind:
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OS << *static_cast<const StringRef*>(Ptr);
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break;
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case Twine::DecUIKind:
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OS << (unsigned)(uintptr_t)Ptr;
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break;
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case Twine::DecIKind:
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OS << (int)(intptr_t)Ptr;
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break;
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case Twine::DecULKind:
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OS << *static_cast<const unsigned long*>(Ptr);
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break;
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case Twine::DecLKind:
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OS << *static_cast<const long*>(Ptr);
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break;
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case Twine::DecULLKind:
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OS << *static_cast<const unsigned long long*>(Ptr);
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break;
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case Twine::DecLLKind:
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OS << *static_cast<const long long*>(Ptr);
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break;
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case Twine::UHexKind:
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OS.write_hex(*static_cast<const uint64_t*>(Ptr));
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break;
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}
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}
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void Twine::printOneChildRepr(raw_ostream &OS, const void *Ptr,
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NodeKind Kind) const {
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switch (Kind) {
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case Twine::NullKind:
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OS << "null"; break;
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case Twine::EmptyKind:
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OS << "empty"; break;
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case Twine::TwineKind:
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OS << "rope:";
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static_cast<const Twine*>(Ptr)->printRepr(OS);
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break;
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case Twine::CStringKind:
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OS << "cstring:\""
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<< static_cast<const char*>(Ptr) << "\"";
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break;
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case Twine::StdStringKind:
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OS << "std::string:\""
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<< static_cast<const std::string*>(Ptr) << "\"";
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break;
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case Twine::StringRefKind:
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OS << "stringref:\""
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<< static_cast<const StringRef*>(Ptr) << "\"";
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break;
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case Twine::DecUIKind:
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OS << "decUI:\"" << (unsigned)(uintptr_t)Ptr << "\"";
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break;
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case Twine::DecIKind:
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OS << "decI:\"" << (int)(intptr_t)Ptr << "\"";
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break;
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case Twine::DecULKind:
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OS << "decUL:\"" << *static_cast<const unsigned long*>(Ptr) << "\"";
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break;
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case Twine::DecLKind:
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OS << "decL:\"" << *static_cast<const long*>(Ptr) << "\"";
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break;
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case Twine::DecULLKind:
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OS << "decULL:\"" << *static_cast<const unsigned long long*>(Ptr) << "\"";
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break;
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case Twine::DecLLKind:
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OS << "decLL:\"" << *static_cast<const long long*>(Ptr) << "\"";
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break;
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case Twine::UHexKind:
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OS << "uhex:\"" << static_cast<const uint64_t*>(Ptr) << "\"";
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break;
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}
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}
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void Twine::print(raw_ostream &OS) const {
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printOneChild(OS, LHS, getLHSKind());
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printOneChild(OS, RHS, getRHSKind());
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}
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void Twine::printRepr(raw_ostream &OS) const {
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OS << "(Twine ";
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printOneChildRepr(OS, LHS, getLHSKind());
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OS << " ";
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printOneChildRepr(OS, RHS, getRHSKind());
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OS << ")";
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}
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void Twine::dump() const {
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print(llvm::dbgs());
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}
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void Twine::dumpRepr() const {
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printRepr(llvm::dbgs());
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}
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