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[X86] Initialize FMA3Info directly in its constructor instead of relying on std::call_once

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FMA3Info only exists as a managed static. As far as I know the ManagedStatic construction proccess is thread safe. It doesn't look like we ever access the ManagedStatic object without immediately doing a query on it that would require the map to be populated. So I don't think we're ever deferring the calculation of the tables from the construction of the object.

So I think we should be able to just populate the FMA3Info map directly in the constructor and get rid of all of the initGroupsOnce stuff.

Differential Revision: https://reviews.llvm.org/D48194

llvm-svn: 335064
This commit is contained in:
Craig Topper 2018-06-19 18:06:52 +00:00
parent 0fce14307b
commit 9b3d8dac02
2 changed files with 2 additions and 27 deletions
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11
lib/Target/X86/X86InstrFMA3Info.cpp
View File

@ -21,10 +21,6 @@
using namespace llvm;
/// This flag is used in the method llvm::call_once() used below to make the
/// initialization of the map 'OpcodeToGroup' thread safe.
static llvm::once_flag InitGroupsOnceFlag;
static ManagedStatic<X86InstrFMA3Info> X86InstrFMA3InfoObj;
X86InstrFMA3Info *X86InstrFMA3Info::getX86InstrFMA3Info() {
return &*X86InstrFMA3InfoObj;
@ -233,7 +229,7 @@ static const X86InstrFMA3Group Groups[] = {
FMA3_AVX512_VECTOR_GROUP(VFMSUBADD)
};
void X86InstrFMA3Info::initGroupsOnceImpl() {
X86InstrFMA3Info::X86InstrFMA3Info() {
for (const X86InstrFMA3Group &G : Groups) {
if (G.RegOpcodes[0])
OpcodeToGroup[G.RegOpcodes[0]] = &G;
@ -249,8 +245,3 @@ void X86InstrFMA3Info::initGroupsOnceImpl() {
OpcodeToGroup[G.MemOpcodes[2]] = &G;
}
}
void X86InstrFMA3Info::initGroupsOnce() {
llvm::call_once(InitGroupsOnceFlag,
[]() { getX86InstrFMA3Info()->initGroupsOnceImpl(); });
}

18
lib/Target/X86/X86InstrFMA3Info.h
View File

@ -151,31 +151,18 @@ private:
/// from the group.
DenseMap<unsigned, const X86InstrFMA3Group *> OpcodeToGroup;
/// Creates groups of FMA opcodes and initializes Opcode-to-Group map.
/// This method can be called many times, but the actual initialization is
/// called only once.
static void initGroupsOnce();
/// Creates groups of FMA opcodes and initializes Opcode-to-Group map.
/// This method must be called ONLY from initGroupsOnce(). Otherwise, such
/// call is not thread safe.
void initGroupsOnceImpl();
public:
/// Returns the reference to an object of this class. It is assumed that
/// only one object may exist.
static X86InstrFMA3Info *getX86InstrFMA3Info();
/// Constructor. Just creates an object of the class.
X86InstrFMA3Info() = default;
X86InstrFMA3Info();
/// Returns a reference to a group of FMA3 opcodes to where the given
/// \p Opcode is included. If the given \p Opcode is not recognized as FMA3
/// and not included into any FMA3 group, then nullptr is returned.
static const X86InstrFMA3Group *getFMA3Group(unsigned Opcode) {
// Ensure that the groups of opcodes are initialized.
initGroupsOnce();
// Find the group including the given opcode.
const X86InstrFMA3Info *FMA3Info = getX86InstrFMA3Info();
auto I = FMA3Info->OpcodeToGroup.find(Opcode);
@ -189,9 +176,6 @@ public:
static bool isFMA3(unsigned Opcode) {
return getFMA3Group(Opcode) != nullptr;
}
/// Iterator that is used to walk on FMA register opcodes having memory
/// form equivalents.
};
} // end namespace llvm