IR: Split Metadata from Value
Split `Metadata` away from the `Value` class hierarchy, as part of
PR21532. Assembly and bitcode changes are in the wings, but this is the
bulk of the change for the IR C++ API.
I have a follow-up patch prepared for `clang`. If this breaks other
sub-projects, I apologize in advance :(. Help me compile it on Darwin
I'll try to fix it. FWIW, the errors should be easy to fix, so it may
be simpler to just fix it yourself.
This breaks the build for all metadata-related code that's out-of-tree.
Rest assured the transition is mechanical and the compiler should catch
almost all of the problems.
Here's a quick guide for updating your code:
- `Metadata` is the root of a class hierarchy with three main classes:
`MDNode`, `MDString`, and `ValueAsMetadata`. It is distinct from
the `Value` class hierarchy. It is typeless -- i.e., instances do
*not* have a `Type`.
- `MDNode`'s operands are all `Metadata *` (instead of `Value *`).
- `TrackingVH<MDNode>` and `WeakVH` referring to metadata can be
replaced with `TrackingMDNodeRef` and `TrackingMDRef`, respectively.
If you're referring solely to resolved `MDNode`s -- post graph
construction -- just use `MDNode*`.
- `MDNode` (and the rest of `Metadata`) have only limited support for
`replaceAllUsesWith()`.
As long as an `MDNode` is pointing at a forward declaration -- the
result of `MDNode::getTemporary()` -- it maintains a side map of its
uses and can RAUW itself. Once the forward declarations are fully
resolved RAUW support is dropped on the ground. This means that
uniquing collisions on changing operands cause nodes to become
"distinct". (This already happened fairly commonly, whenever an
operand went to null.)
If you're constructing complex (non self-reference) `MDNode` cycles,
you need to call `MDNode::resolveCycles()` on each node (or on a
top-level node that somehow references all of the nodes). Also,
don't do that. Metadata cycles (and the RAUW machinery needed to
construct them) are expensive.
- An `MDNode` can only refer to a `Constant` through a bridge called
`ConstantAsMetadata` (one of the subclasses of `ValueAsMetadata`).
As a side effect, accessing an operand of an `MDNode` that is known
to be, e.g., `ConstantInt`, takes three steps: first, cast from
`Metadata` to `ConstantAsMetadata`; second, extract the `Constant`;
third, cast down to `ConstantInt`.
The eventual goal is to introduce `MDInt`/`MDFloat`/etc. and have
metadata schema owners transition away from using `Constant`s when
the type isn't important (and they don't care about referring to
`GlobalValue`s).
In the meantime, I've added transitional API to the `mdconst`
namespace that matches semantics with the old code, in order to
avoid adding the error-prone three-step equivalent to every call
site. If your old code was:
MDNode *N = foo();
bar(isa <ConstantInt>(N->getOperand(0)));
baz(cast <ConstantInt>(N->getOperand(1)));
bak(cast_or_null <ConstantInt>(N->getOperand(2)));
bat(dyn_cast <ConstantInt>(N->getOperand(3)));
bay(dyn_cast_or_null<ConstantInt>(N->getOperand(4)));
you can trivially match its semantics with:
MDNode *N = foo();
bar(mdconst::hasa <ConstantInt>(N->getOperand(0)));
baz(mdconst::extract <ConstantInt>(N->getOperand(1)));
bak(mdconst::extract_or_null <ConstantInt>(N->getOperand(2)));
bat(mdconst::dyn_extract <ConstantInt>(N->getOperand(3)));
bay(mdconst::dyn_extract_or_null<ConstantInt>(N->getOperand(4)));
and when you transition your metadata schema to `MDInt`:
MDNode *N = foo();
bar(isa <MDInt>(N->getOperand(0)));
baz(cast <MDInt>(N->getOperand(1)));
bak(cast_or_null <MDInt>(N->getOperand(2)));
bat(dyn_cast <MDInt>(N->getOperand(3)));
bay(dyn_cast_or_null<MDInt>(N->getOperand(4)));
- A `CallInst` -- specifically, intrinsic instructions -- can refer to
metadata through a bridge called `MetadataAsValue`. This is a
subclass of `Value` where `getType()->isMetadataTy()`.
`MetadataAsValue` is the *only* class that can legally refer to a
`LocalAsMetadata`, which is a bridged form of non-`Constant` values
like `Argument` and `Instruction`. It can also refer to any other
`Metadata` subclass.
(I'll break all your testcases in a follow-up commit, when I propagate
this change to assembly.)
llvm-svn: 223802
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index 90f16f5..d3fdbcc 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -798,7 +798,7 @@
if (const Module *SourceModule = MMI->getModule()) {
// ABI_PCS_wchar_t to indicate wchar_t width
// FIXME: There is no way to emit value 0 (wchar_t prohibited).
- if (auto WCharWidthValue = cast_or_null<ConstantInt>(
+ if (auto WCharWidthValue = mdconst::extract_or_null<ConstantInt>(
SourceModule->getModuleFlag("wchar_size"))) {
int WCharWidth = WCharWidthValue->getZExtValue();
assert((WCharWidth == 2 || WCharWidth == 4) &&
@@ -809,7 +809,7 @@
// ABI_enum_size to indicate enum width
// FIXME: There is no way to emit value 0 (enums prohibited) or value 3
// (all enums contain a value needing 32 bits to encode).
- if (auto EnumWidthValue = cast_or_null<ConstantInt>(
+ if (auto EnumWidthValue = mdconst::extract_or_null<ConstantInt>(
SourceModule->getModuleFlag("min_enum_size"))) {
int EnumWidth = EnumWidthValue->getZExtValue();
assert((EnumWidth == 1 || EnumWidth == 4) &&
diff --git a/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp b/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp
index 58fa95b..e50f6de 100644
--- a/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp
+++ b/llvm/lib/Target/NVPTX/NVPTXGenericToNVVM.cpp
@@ -394,31 +394,34 @@
MDNode *GenericToNVVM::remapMDNode(Module *M, MDNode *N) {
bool OperandChanged = false;
- SmallVector<Value *, 8> NewOperands;
+ SmallVector<Metadata *, 8> NewOperands;
unsigned NumOperands = N->getNumOperands();
// Check if any operand is or contains a global variable in GVMap, and thus
// converted to another value.
for (unsigned i = 0; i < NumOperands; ++i) {
- Value *Operand = N->getOperand(i);
- Value *NewOperand = Operand;
+ Metadata *Operand = N->getOperand(i);
+ Metadata *NewOperand = Operand;
if (Operand) {
- if (isa<GlobalVariable>(Operand)) {
- GVMapTy::iterator I = GVMap.find(cast<GlobalVariable>(Operand));
- if (I != GVMap.end()) {
- NewOperand = I->second;
- if (++i < NumOperands) {
- NewOperands.push_back(NewOperand);
- // Address space of the global variable follows the global variable
- // in the global variable debug info (see createGlobalVariable in
- // lib/Analysis/DIBuilder.cpp).
- NewOperand =
- ConstantInt::get(Type::getInt32Ty(M->getContext()),
- I->second->getType()->getAddressSpace());
+ if (auto *N = dyn_cast<MDNode>(Operand)) {
+ NewOperand = remapMDNode(M, N);
+ } else if (auto *C = dyn_cast<ConstantAsMetadata>(Operand)) {
+ if (auto *G = dyn_cast<GlobalVariable>(C->getValue())) {
+ GVMapTy::iterator I = GVMap.find(G);
+ if (I != GVMap.end()) {
+ NewOperand = ConstantAsMetadata::get(I->second);
+ if (++i < NumOperands) {
+ NewOperands.push_back(NewOperand);
+ // Address space of the global variable follows the global
+ // variable
+ // in the global variable debug info (see createGlobalVariable in
+ // lib/Analysis/DIBuilder.cpp).
+ NewOperand = ConstantAsMetadata::get(
+ ConstantInt::get(Type::getInt32Ty(M->getContext()),
+ I->second->getType()->getAddressSpace()));
+ }
}
}
- } else if (isa<MDNode>(Operand)) {
- NewOperand = remapMDNode(M, cast<MDNode>(Operand));
}
}
OperandChanged |= Operand != NewOperand;
diff --git a/llvm/lib/Target/NVPTX/NVPTXUtilities.cpp b/llvm/lib/Target/NVPTX/NVPTXUtilities.cpp
index 5caa8bd..5d896b4 100644
--- a/llvm/lib/Target/NVPTX/NVPTXUtilities.cpp
+++ b/llvm/lib/Target/NVPTX/NVPTXUtilities.cpp
@@ -52,7 +52,7 @@
assert(prop && "Annotation property not a string");
// value
- ConstantInt *Val = dyn_cast<ConstantInt>(md->getOperand(i + 1));
+ ConstantInt *Val = mdconst::dyn_extract<ConstantInt>(md->getOperand(i + 1));
assert(Val && "Value operand not a constant int");
std::string keyname = prop->getString().str();
@@ -75,7 +75,8 @@
for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
const MDNode *elem = NMD->getOperand(i);
- Value *entity = elem->getOperand(0);
+ GlobalValue *entity =
+ mdconst::dyn_extract_or_null<GlobalValue>(elem->getOperand(0));
// entity may be null due to DCE
if (!entity)
continue;
@@ -322,7 +323,7 @@
if (MDNode *alignNode = I.getMetadata("callalign")) {
for (int i = 0, n = alignNode->getNumOperands(); i < n; i++) {
if (const ConstantInt *CI =
- dyn_cast<ConstantInt>(alignNode->getOperand(i))) {
+ mdconst::dyn_extract<ConstantInt>(alignNode->getOperand(i))) {
unsigned v = CI->getZExtValue();
if ((v >> 16) == index) {
align = v & 0xFFFF;