[GlobalISel] convergence control tokens and intrinsics #67006
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ssahasra
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@llvm/pr-subscribers-llvm-adt @llvm/pr-subscribers-llvm-globalisel ChangesSupport for lowering convergence control to GMIR:
Note that the lowering of the new GMIR opcodes is entirely target-specific. It is generally expected that the backend will use convergence control to change the CFG of each function, and then discard the tokens. This is currently a work in progress for AMDGPU. Differential Revision: https://reviews.llvm.org/D158147 Patch is 42.64 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/67006.diff 26 Files Affected:
diff --git a/llvm/include/llvm/ADT/GenericConvergenceVerifier.h b/llvm/include/llvm/ADT/GenericConvergenceVerifier.h
index 0810a0701322907..24cd0cda3708517 100644
--- a/llvm/include/llvm/ADT/GenericConvergenceVerifier.h
+++ b/llvm/include/llvm/ADT/GenericConvergenceVerifier.h
@@ -60,6 +60,10 @@ template <typename ContextT> class GenericConvergenceVerifier {
NoConvergence
} ConvergenceKind = NoConvergence;
+ /// The control token operation performed by a convergence control Intrinsic in LLVM IR,
+ /// or by a G_CONVERGENCECTRL* instruction in GMIR.
+ enum ConvOpKind { CONV_ANCHOR, CONV_ENTRY, CONV_LOOP, CONV_NONE };
+
// Cache token uses found so far. Note that we track the unique definitions
// and not the token values.
DenseMap<const InstructionT *, const InstructionT *> Tokens;
@@ -68,6 +72,7 @@ template <typename ContextT> class GenericConvergenceVerifier {
static bool isInsideConvergentFunction(const InstructionT &I);
static bool isConvergent(const InstructionT &I);
+ static ConvOpKind getConvOp(const InstructionT &I);
const InstructionT *findAndCheckConvergenceTokenUsed(const InstructionT &I);
void reportFailure(const Twine &Message, ArrayRef<Printable> Values);
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
index 4a799eec8899a51..ff2721495dc3b97 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
@@ -117,6 +117,9 @@ class CallLowering {
/// vreg that the swifterror should be copied into after the call.
Register SwiftErrorVReg;
+ /// Valid if the call is a controlled convergent operation.
+ Register ConvergenceCtrlToken;
+
/// Original IR callsite corresponding to this call, if available.
const CallBase *CB = nullptr;
@@ -583,6 +586,7 @@ class CallLowering {
bool lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &Call,
ArrayRef<Register> ResRegs,
ArrayRef<ArrayRef<Register>> ArgRegs, Register SwiftErrorVReg,
+ Register ConvergenceCtrlToken,
std::function<unsigned()> GetCalleeReg) const;
/// For targets which want to use big-endian can enable it with
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/IRTranslator.h b/llvm/include/llvm/CodeGen/GlobalISel/IRTranslator.h
index bffc03ed0187e63..d51daa926c9575d 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/IRTranslator.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/IRTranslator.h
@@ -554,6 +554,10 @@ class IRTranslator : public MachineFunctionPass {
return false;
}
+ bool translateConvergenceControlIntrinsic(const CallInst &CI,
+ Intrinsic::ID ID,
+ MachineIRBuilder &MIRBuilder);
+
/// @}
// Builder for machine instruction a la IRBuilder.
@@ -671,6 +675,23 @@ class IRTranslator : public MachineFunctionPass {
return Regs[0];
}
+ Register getOrCreateConvergenceTokenVReg(const Value &Token) {
+ assert(Token.getType()->isTokenTy());
+ auto &Regs = *VMap.getVRegs(Token);
+ if (!Regs.empty()) {
+ assert(Regs.size() == 1 &&
+ "Expected a single register for convergence tokens.");
+ return Regs[0];
+ }
+
+ auto Reg = MRI->createGenericVirtualRegister(LLT::token());
+ Regs.push_back(Reg);
+ auto &Offsets = *VMap.getOffsets(Token);
+ if (Offsets.empty())
+ Offsets.push_back(0);
+ return Reg;
+ }
+
/// Allocate some vregs and offsets in the VMap. Then populate just the
/// offsets while leaving the vregs empty.
ValueToVRegInfo::VRegListT &allocateVRegs(const Value &Val);
diff --git a/llvm/include/llvm/CodeGen/LowLevelType.h b/llvm/include/llvm/CodeGen/LowLevelType.h
index b7477834a1ff5e1..e0cd56849909422 100644
--- a/llvm/include/llvm/CodeGen/LowLevelType.h
+++ b/llvm/include/llvm/CodeGen/LowLevelType.h
@@ -45,6 +45,13 @@ class LLT {
/*AddressSpace=*/0};
}
+ /// Get a low-level token; just a scalar with zero bits (or no size).
+ static constexpr LLT token() {
+ return LLT{/*isPointer=*/false, /*isVector=*/false, /*isScalar=*/true,
+ ElementCount::getFixed(0), /*SizeInBits=*/0,
+ /*AddressSpace=*/0};
+ }
+
/// Get a low-level pointer in the given address space.
static constexpr LLT pointer(unsigned AddressSpace, unsigned SizeInBits) {
assert(SizeInBits > 0 && "invalid pointer size");
@@ -304,6 +311,28 @@ class LLT {
/// described in static const *Field variables. Each of these variables
/// is a 2-element array, with the first element describing the bitfield size
/// and the second element describing the bitfield offset.
+ ///
+ /// +--------+---------+--------+----------+----------------------+
+ /// |isScalar|isPointer|isVector| RawData |Notes |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 0 | 0 | 0 | 0 |Invalid |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 0 | 0 | 1 | 0 |Tombstone Key |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 0 | 1 | 0 | 0 |Empty Key |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 1 | 0 | 0 | 0 |Token |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 1 | 0 | 0 | non-zero |Scalar |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 0 | 1 | 0 | non-zero |Pointer |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 0 | 0 | 1 | non-zero |Vector of non-pointer |
+ /// +--------+---------+--------+----------+----------------------+
+ /// | 0 | 1 | 1 | non-zero |Vector of pointer |
+ /// +--------+---------+--------+----------+----------------------+
+ ///
+ /// Everything else is reserved.
typedef int BitFieldInfo[2];
///
/// This is how the bitfields are packed per Kind:
diff --git a/llvm/include/llvm/CodeGen/MachineConvergenceVerifier.h b/llvm/include/llvm/CodeGen/MachineConvergenceVerifier.h
new file mode 100644
index 000000000000000..fd13546f2ae32f0
--- /dev/null
+++ b/llvm/include/llvm/CodeGen/MachineConvergenceVerifier.h
@@ -0,0 +1,28 @@
+//===- MachineConvergenceVerifier.h - Verify convergenctrl ------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file declares the GMIR IR specialization of the
+/// GenericConvergenceVerifier template.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINECONVERGENCEVERIFIER_H
+#define LLVM_CODEGEN_MACHINECONVERGENCEVERIFIER_H
+
+#include "llvm/ADT/GenericConvergenceVerifier.h"
+#include "llvm/CodeGen/MachineSSAContext.h"
+
+namespace llvm {
+
+using MachineConvergenceVerifier =
+ GenericConvergenceVerifier<MachineSSAContext>;
+
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_MACHINECONVERGENCEVERIFIER_H
diff --git a/llvm/include/llvm/IR/GenericConvergenceVerifierImpl.h b/llvm/include/llvm/IR/GenericConvergenceVerifierImpl.h
index 2ba81015cb7b641..037e406fc57d38b 100644
--- a/llvm/include/llvm/IR/GenericConvergenceVerifierImpl.h
+++ b/llvm/include/llvm/IR/GenericConvergenceVerifierImpl.h
@@ -49,17 +49,6 @@ using namespace llvm;
} \
} while (false)
-static bool isConvergenceControlIntrinsic(unsigned IntrinsicID) {
- switch (IntrinsicID) {
- default:
- return false;
- case Intrinsic::experimental_convergence_anchor:
- case Intrinsic::experimental_convergence_entry:
- case Intrinsic::experimental_convergence_loop:
- return true;
- }
-}
-
namespace llvm {
template <class ContextT> void GenericConvergenceVerifier<ContextT>::clear() {
Tokens.clear();
@@ -74,12 +63,11 @@ void GenericConvergenceVerifier<ContextT>::visit(const BlockT &BB) {
template <class ContextT>
void GenericConvergenceVerifier<ContextT>::visit(const InstructionT &I) {
- auto ID = ContextT::getIntrinsicID(I);
+ auto ConvOp = getConvOp(I);
auto *TokenDef = findAndCheckConvergenceTokenUsed(I);
- bool IsCtrlIntrinsic = true;
- switch (ID) {
- case Intrinsic::experimental_convergence_entry:
+ switch (ConvOp) {
+ case CONV_ENTRY:
Check(isInsideConvergentFunction(I),
"Entry intrinsic can occur only in a convergent function.",
{Context.print(&I)});
@@ -91,13 +79,13 @@ void GenericConvergenceVerifier<ContextT>::visit(const InstructionT &I) {
"same basic block.",
{Context.print(&I)});
LLVM_FALLTHROUGH;
- case Intrinsic::experimental_convergence_anchor:
+ case CONV_ANCHOR:
Check(!TokenDef,
"Entry or anchor intrinsic cannot have a convergencectrl token "
"operand.",
{Context.print(&I)});
break;
- case Intrinsic::experimental_convergence_loop:
+ case CONV_LOOP:
Check(TokenDef, "Loop intrinsic must have a convergencectrl token operand.",
{Context.print(&I)});
Check(!SeenFirstConvOp,
@@ -106,14 +94,13 @@ void GenericConvergenceVerifier<ContextT>::visit(const InstructionT &I) {
{Context.print(&I)});
break;
default:
- IsCtrlIntrinsic = false;
break;
}
if (isConvergent(I))
SeenFirstConvOp = true;
- if (TokenDef || IsCtrlIntrinsic) {
+ if (TokenDef || ConvOp != CONV_NONE) {
Check(isConvergent(I),
"Convergence control token can only be used in a convergent call.",
{Context.print(&I)});
@@ -174,8 +161,7 @@ void GenericConvergenceVerifier<ContextT>::verify(const DominatorTreeT &DT) {
return;
}
- Check(ContextT::getIntrinsicID(*User) ==
- Intrinsic::experimental_convergence_loop,
+ Check(getConvOp(*User) == CONV_LOOP,
"Convergence token used by an instruction other than "
"llvm.experimental.convergence.loop in a cycle that does "
"not contain the token's definition.",
@@ -212,7 +198,7 @@ void GenericConvergenceVerifier<ContextT>::verify(const DominatorTreeT &DT) {
for (auto &I : *BB) {
if (auto *Token = Tokens.lookup(&I))
checkToken(Token, &I, LiveTokens);
- if (isConvergenceControlIntrinsic(ContextT::getIntrinsicID(I)))
+ if (getConvOp(I) != CONV_NONE)
LiveTokens.push_back(&I);
}
diff --git a/llvm/include/llvm/Support/TargetOpcodes.def b/llvm/include/llvm/Support/TargetOpcodes.def
index e02b1a1d01cfec0..04bdc395b302235 100644
--- a/llvm/include/llvm/Support/TargetOpcodes.def
+++ b/llvm/include/llvm/Support/TargetOpcodes.def
@@ -436,6 +436,10 @@ HANDLE_TARGET_OPCODE(G_INTRINSIC_CONVERGENT)
/// Generic intrinsic use (with side effects).
HANDLE_TARGET_OPCODE(G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS)
+HANDLE_TARGET_OPCODE(G_CONVERGENCECTRL_ENTRY)
+HANDLE_TARGET_OPCODE(G_CONVERGENCECTRL_ANCHOR)
+HANDLE_TARGET_OPCODE(G_CONVERGENCECTRL_LOOP)
+
/// Generic extension allowing rubbish in high bits.
HANDLE_TARGET_OPCODE(G_ANYEXT)
diff --git a/llvm/include/llvm/Target/GenericOpcodes.td b/llvm/include/llvm/Target/GenericOpcodes.td
index 0a4fbaa12f96cec..27d4b8a4759ff92 100644
--- a/llvm/include/llvm/Target/GenericOpcodes.td
+++ b/llvm/include/llvm/Target/GenericOpcodes.td
@@ -1276,6 +1276,34 @@ def G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS : GenericInstruction {
let isConvergent = true;
}
+//------------------------------------------------------------------------------
+// Convergence control operations.
+//------------------------------------------------------------------------------
+
+// Capture the set of threads that are converged on entry to a function.
+def G_CONVERGENCECTRL_ENTRY : GenericInstruction {
+ let InOperandList = (ins);
+ let OutOperandList = (outs type0:$dst);
+ let isConvergent = true;
+ let hasSideEffects = false;
+}
+
+// Capture an implementation-defined subset of converged threads.
+def G_CONVERGENCECTRL_ANCHOR : GenericInstruction {
+ let InOperandList = (ins);
+ let OutOperandList = (outs type0:$dst);
+ let isConvergent = true;
+ let hasSideEffects = false;
+}
+
+// Capture the convergence of threads in a cycle.
+def G_CONVERGENCECTRL_LOOP : GenericInstruction {
+ let InOperandList = (ins type0:$src);
+ let OutOperandList = (outs type0:$dst);
+ let isConvergent = true;
+ let hasSideEffects = false;
+}
+
//------------------------------------------------------------------------------
// Branches.
//------------------------------------------------------------------------------
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 389c70d04f17ba3..41f6612b68a1f12 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -121,6 +121,7 @@ add_llvm_component_library(LLVMCodeGen
MachineBranchProbabilityInfo.cpp
MachineCFGPrinter.cpp
MachineCombiner.cpp
+ MachineConvergenceVerifier.cpp
MachineCopyPropagation.cpp
MachineCSE.cpp
MachineCheckDebugify.cpp
diff --git a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
index 0b1f151135be9fc..45738cc636cb7af 100644
--- a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
@@ -21,6 +21,7 @@
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Target/TargetMachine.h"
@@ -87,10 +88,20 @@ void CallLowering::addArgFlagsFromAttributes(ISD::ArgFlagsTy &Flags,
});
}
+static bool hasConvergenceEntryToken(const CallBase &CB) {
+ auto Bundle = CB.getOperandBundle(LLVMContext::OB_convergencectrl);
+ if (!Bundle)
+ return true;
+ auto *Token = Bundle->Inputs[0].get();
+ auto *Def = cast<IntrinsicInst>(Token);
+ return Def->getIntrinsicID() == Intrinsic::experimental_convergence_entry;
+}
+
bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
ArrayRef<Register> ResRegs,
ArrayRef<ArrayRef<Register>> ArgRegs,
Register SwiftErrorVReg,
+ Register ConvergenceCtrlToken,
std::function<unsigned()> GetCalleeReg) const {
CallLoweringInfo Info;
const DataLayout &DL = MIRBuilder.getDataLayout();
@@ -121,6 +132,8 @@ bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
CanBeTailCalled = false;
}
+ if (!hasConvergenceEntryToken(CB))
+ CanBeTailCalled = false;
// First step is to marshall all the function's parameters into the correct
// physregs and memory locations. Gather the sequence of argument types that
@@ -176,6 +189,7 @@ bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
Info.KnownCallees = CB.getMetadata(LLVMContext::MD_callees);
Info.CallConv = CallConv;
Info.SwiftErrorVReg = SwiftErrorVReg;
+ Info.ConvergenceCtrlToken = ConvergenceCtrlToken;
Info.IsMustTailCall = CB.isMustTailCall();
Info.IsTailCall = CanBeTailCalled;
Info.IsVarArg = IsVarArg;
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 9dac3d083994f9f..692e2fbdb313add 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -210,8 +210,9 @@ ArrayRef<Register> IRTranslator::getOrCreateVRegs(const Value &Val) {
auto *VRegs = VMap.getVRegs(Val);
auto *Offsets = VMap.getOffsets(Val);
- assert(Val.getType()->isSized() &&
- "Don't know how to create an empty vreg");
+ if (!Val.getType()->isTokenTy())
+ assert(Val.getType()->isSized() &&
+ "Don't know how to create an empty vreg");
SmallVector<LLT, 4> SplitTys;
computeValueLLTs(*DL, *Val.getType(), SplitTys,
@@ -1953,6 +1954,37 @@ bool IRTranslator::translateIfEntryValueArgument(
return true;
}
+static unsigned getConvOpcode(Intrinsic::ID ID) {
+ switch (ID) {
+ default:
+ llvm_unreachable("Unexpected intrinsic");
+ return 0;
+ case Intrinsic::experimental_convergence_anchor:
+ return TargetOpcode::G_CONVERGENCECTRL_ANCHOR;
+ case Intrinsic::experimental_convergence_entry:
+ return TargetOpcode::G_CONVERGENCECTRL_ENTRY;
+ case Intrinsic::experimental_convergence_loop:
+ return TargetOpcode::G_CONVERGENCECTRL_LOOP;
+ }
+}
+
+bool IRTranslator::translateConvergenceControlIntrinsic(
+ const CallInst &CI, Intrinsic::ID ID, MachineIRBuilder &MIRBuilder) {
+ MachineInstrBuilder MIB = MIRBuilder.buildInstr(getConvOpcode(ID));
+ Register OutputReg = getOrCreateConvergenceTokenVReg(CI);
+ MIB.addDef(OutputReg);
+
+ if (ID == Intrinsic::experimental_convergence_loop) {
+ auto Bundle = CI.getOperandBundle(LLVMContext::OB_convergencectrl);
+ assert(Bundle && "Expected a convergence control token.");
+ Register InputReg =
+ getOrCreateConvergenceTokenVReg(*Bundle->Inputs[0].get());
+ MIB.addUse(InputReg);
+ }
+
+ return true;
+}
+
bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
MachineIRBuilder &MIRBuilder) {
if (auto *MI = dyn_cast<AnyMemIntrinsic>(&CI)) {
@@ -2410,7 +2442,10 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
#include "llvm/IR/ConstrainedOps.def"
return translateConstrainedFPIntrinsic(cast<ConstrainedFPIntrinsic>(CI),
MIRBuilder);
-
+ case Intrinsic::experimental_convergence_anchor:
+ case Intrinsic::experimental_convergence_entry:
+ case Intrinsic::experimental_convergence_loop:
+ return translateConvergenceControlIntrinsic(CI, ID, MIRBuilder);
}
return false;
}
@@ -2461,12 +2496,18 @@ bool IRTranslator::translateCallBase(const CallBase &CB,
}
}
+ Register ConvergenceCtrlToken = 0;
+ if (auto Bundle = CB.getOperandBundle(LLVMContext::OB_convergencectrl)) {
+ const auto &Token = *Bundle->Inputs[0].get();
+ ConvergenceCtrlToken = getOrCreateConvergenceTokenVReg(Token);
+ }
+
// We don't set HasCalls on MFI here yet because call lowering may decide to
// optimize into tail calls. Instead, we defer that to selection where a final
// scan is done to check if any instructions are calls.
- bool Success =
- CLI->lowerCall(MIRBuilder, CB, Res, Args, SwiftErrorVReg,
- [&]() { return getOrCreateVReg(*CB.getCalledOperand()); });
+ bool Success = CLI->lowerCall(
+ MIRBuilder, CB, Res, Args, SwiftErrorVReg, ConvergenceCtrlToken,
+ [&]() { return getOrCreateVReg(*CB.getCalledOperand()); });
// Check if we just inserted a tail call.
if (Success) {
@@ -2581,6 +2622,14 @@ bool IRTranslator::translateCall(const User &U, MachineIRBuilder &MIRBuilder) {
MF->getMachineMemOperand(MPI, Info.flags, MemTy, Alignment, CI.getAAMetadata()));
}
+ if (CI.isConvergent()) {
+ if (auto Bundle = CI.getOperandBundle(LLVMContext::OB_convergencectrl)) {
+ auto *Token = Bundle->Inputs[0].get();
+ Register TokenReg = getOrCreateVReg(*Token);
+ MIB.addUse(TokenReg, RegState::Implicit);
+ }
+ }
+
return true;
}
diff --git a/llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp b/llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
index 00dba57fcb80227..2dfaa7381ae3355 100644
--- a/llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp
@@ -592,6 +592,14 @@ bool InlineAsmLowering::lowerInlineAsm(
}
}
+ if (auto Bundle = Call.getOperandBundle(LLVMContext::OB_convergencectrl)) {
+ auto *Token = Bundle->Inputs[0].get();
+ ArrayRef<Register> SourceRegs = GetOrCreateVRegs(*Token);
+ assert(SourceRegs.size() == 1 &&
+ "Expected the control token to f...
[truncated]
|
nhaehnle
reviewed
Sep 26, 2023
arsenm
reviewed
Oct 24, 2023
| // that since the token type may have other implicit uses. Instead we use it | ||
| // as a way to identify convergence control token operands. | ||
| const auto *Def = MRI.getUniqueVRegDef(MO.getReg()); | ||
| if (!Def) |
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This can't happen for G_* instructions (and ideally would be impossible for all of SSA)
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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ssahasra
commented
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llvm/test/CodeGen/AMDGPU/GlobalISel/irtranslator-convergence-tokens.ll
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arsenm
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The new token type is used in llvm#67006 for implementing convergence control tokens in GMIR.
In the IR translator, convert the LLVM token type to LLT::token(), which is an alias for the s0 type. These show up as implicit uses on convergent operations. Differential Revision: https://reviews.llvm.org/D158147
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The new token type is used in #67006 for implementing convergence control tokens in GMIR.
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Support for lowering convergence control to GMIR:
Note that the lowering of the new GMIR opcodes is entirely target-specific. It is generally expected that the backend will use convergence control to change the CFG of each function, and then discard the tokens. This is currently a work in progress for AMDGPU.
Differential Revision: https://reviews.llvm.org/D158147