[clang][SPIR-V] Always add convervence intrinsics

PR #80680 added bits in the codegen to lazily add convergence intrinsics
when required. This logic relied on the LoopStack. The issue is
when parsing the condition, the loopstack doesn't yet reflect the
correct values, as expected since we are not yet in the loop.

However, convergence tokens should sometimes already be available.
The solution which seemed the simplest is to greedily generate the
tokens when we generate SPIR-V.

Fixes #88144

Signed-off-by: Nathan Gauër <[email protected]>

Author: Keenuts

clang/lib/CodeGen/CGBuiltin.cpp

@@ -1141,91 +1141,8 @@ struct BitTest {
   static BitTest decodeBitTestBuiltin(unsigned BuiltinID);
 };
 
-// Returns the first convergence entry/loop/anchor instruction found in |BB|.
-// std::nullptr otherwise.
-llvm::IntrinsicInst *getConvergenceToken(llvm::BasicBlock *BB) {
-  for (auto &I : *BB) {
-    auto *II = dyn_cast<llvm::IntrinsicInst>(&I);
-    if (II && isConvergenceControlIntrinsic(II->getIntrinsicID()))
-      return II;
-  }
-  return nullptr;
-}
-
 } // namespace
 
-llvm::CallBase *
-CodeGenFunction::addConvergenceControlToken(llvm::CallBase *Input,
-                                            llvm::Value *ParentToken) {
-  llvm::Value *bundleArgs[] = {ParentToken};
-  llvm::OperandBundleDef OB("convergencectrl", bundleArgs);
-  auto Output = llvm::CallBase::addOperandBundle(
-      Input, llvm::LLVMContext::OB_convergencectrl, OB, Input);
-  Input->replaceAllUsesWith(Output);
-  Input->eraseFromParent();
-  return Output;
-}
-
-llvm::IntrinsicInst *
-CodeGenFunction::emitConvergenceLoopToken(llvm::BasicBlock *BB,
-                                          llvm::Value *ParentToken) {
-  CGBuilderTy::InsertPoint IP = Builder.saveIP();
-  Builder.SetInsertPoint(&BB->front());
-  auto CB = Builder.CreateIntrinsic(
-      llvm::Intrinsic::experimental_convergence_loop, {}, {});
-  Builder.restoreIP(IP);
-
-  auto I = addConvergenceControlToken(CB, ParentToken);
-  return cast<llvm::IntrinsicInst>(I);
-}
-
-llvm::IntrinsicInst *
-CodeGenFunction::getOrEmitConvergenceEntryToken(llvm::Function *F) {
-  auto *BB = &F->getEntryBlock();
-  auto *token = getConvergenceToken(BB);
-  if (token)
-    return token;
-
-  // Adding a convergence token requires the function to be marked as
-  // convergent.
-  F->setConvergent();
-
-  CGBuilderTy::InsertPoint IP = Builder.saveIP();
-  Builder.SetInsertPoint(&BB->front());
-  auto I = Builder.CreateIntrinsic(
-      llvm::Intrinsic::experimental_convergence_entry, {}, {});
-  assert(isa<llvm::IntrinsicInst>(I));
-  Builder.restoreIP(IP);
-
-  return cast<llvm::IntrinsicInst>(I);
-}
-
-llvm::IntrinsicInst *
-CodeGenFunction::getOrEmitConvergenceLoopToken(const LoopInfo *LI) {
-  assert(LI != nullptr);
-
-  auto *token = getConvergenceToken(LI->getHeader());
-  if (token)
-    return token;
-
-  llvm::IntrinsicInst *PII =
-      LI->getParent()
-          ? emitConvergenceLoopToken(
-                LI->getHeader(), getOrEmitConvergenceLoopToken(LI->getParent()))
-          : getOrEmitConvergenceEntryToken(LI->getHeader()->getParent());
-
-  return emitConvergenceLoopToken(LI->getHeader(), PII);
-}
-
-llvm::CallBase *
-CodeGenFunction::addControlledConvergenceToken(llvm::CallBase *Input) {
-  llvm::Value *ParentToken =
-      LoopStack.hasInfo()
-          ? getOrEmitConvergenceLoopToken(&LoopStack.getInfo())
-          : getOrEmitConvergenceEntryToken(Input->getFunction());
-  return addConvergenceControlToken(Input, ParentToken);
-}
-
 BitTest BitTest::decodeBitTestBuiltin(unsigned BuiltinID) {
   switch (BuiltinID) {
     // Main portable variants.
@@ -18400,12 +18317,9 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
         ArrayRef<Value *>{Op0}, nullptr, "dx.rsqrt");
   }
   case Builtin::BI__builtin_hlsl_wave_get_lane_index: {
-    auto *CI = EmitRuntimeCall(CGM.CreateRuntimeFunction(
+    return EmitRuntimeCall(CGM.CreateRuntimeFunction(
         llvm::FunctionType::get(IntTy, {}, false), "__hlsl_wave_get_lane_index",
         {}, false, true));
-    if (getTarget().getTriple().isSPIRVLogical())
-      CI = dyn_cast<CallInst>(addControlledConvergenceToken(CI));
-    return CI;
   }
   }
   return nullptr;

clang/lib/CodeGen/CGCall.cpp

@@ -4830,6 +4830,9 @@ llvm::CallInst *CodeGenFunction::EmitRuntimeCall(llvm::FunctionCallee callee,
   llvm::CallInst *call = Builder.CreateCall(
       callee, args, getBundlesForFunclet(callee.getCallee()), name);
   call->setCallingConv(getRuntimeCC());
+
+  if (getTarget().getTriple().isSPIRVLogical() && call->isConvergent())
+    return dyn_cast<llvm::CallInst>(addControlledConvergenceToken(call));
   return call;
 }
 

clang/lib/CodeGen/CGStmt.cpp

@@ -978,6 +978,10 @@ void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
   JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
   EmitBlock(LoopHeader.getBlock());
 
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.push_back(emitConvergenceLoopToken(
+        LoopHeader.getBlock(), ConvergenceTokenStack.back()));
+
   // Create an exit block for when the condition fails, which will
   // also become the break target.
   JumpDest LoopExit = getJumpDestInCurrentScope("while.end");
@@ -1079,6 +1083,9 @@ void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
   // block.
   if (llvm::EnableSingleByteCoverage)
     incrementProfileCounter(&S);
+
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.pop_back();
 }
 
 void CodeGenFunction::EmitDoStmt(const DoStmt &S,
@@ -1098,6 +1105,11 @@ void CodeGenFunction::EmitDoStmt(const DoStmt &S,
     EmitBlockWithFallThrough(LoopBody, S.getBody());
   else
     EmitBlockWithFallThrough(LoopBody, &S);
+
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.push_back(
+        emitConvergenceLoopToken(LoopBody, ConvergenceTokenStack.back()));
+
   {
     RunCleanupsScope BodyScope(*this);
     EmitStmt(S.getBody());
@@ -1151,6 +1163,9 @@ void CodeGenFunction::EmitDoStmt(const DoStmt &S,
   // block.
   if (llvm::EnableSingleByteCoverage)
     incrementProfileCounter(&S);
+
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.pop_back();
 }
 
 void CodeGenFunction::EmitForStmt(const ForStmt &S,
@@ -1170,6 +1185,10 @@ void CodeGenFunction::EmitForStmt(const ForStmt &S,
   llvm::BasicBlock *CondBlock = CondDest.getBlock();
   EmitBlock(CondBlock);
 
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.push_back(
+        emitConvergenceLoopToken(CondBlock, ConvergenceTokenStack.back()));
+
   const SourceRange &R = S.getSourceRange();
   LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
                  SourceLocToDebugLoc(R.getBegin()),
@@ -1279,6 +1298,9 @@ void CodeGenFunction::EmitForStmt(const ForStmt &S,
   // block.
   if (llvm::EnableSingleByteCoverage)
     incrementProfileCounter(&S);
+
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.pop_back();
 }
 
 void
@@ -1301,6 +1323,10 @@ CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
   llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
   EmitBlock(CondBlock);
 
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.push_back(
+        emitConvergenceLoopToken(CondBlock, ConvergenceTokenStack.back()));
+
   const SourceRange &R = S.getSourceRange();
   LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
                  SourceLocToDebugLoc(R.getBegin()),
@@ -1369,6 +1395,9 @@ CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
   // block.
   if (llvm::EnableSingleByteCoverage)
     incrementProfileCounter(&S);
+
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.pop_back();
 }
 
 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
@@ -3158,3 +3187,68 @@ CodeGenFunction::GenerateCapturedStmtFunction(const CapturedStmt &S) {
 
   return F;
 }
+
+namespace {
+// Returns the first convergence entry/loop/anchor instruction found in |BB|.
+// std::nullptr otherwise.
+llvm::IntrinsicInst *getConvergenceToken(llvm::BasicBlock *BB) {
+  for (auto &I : *BB) {
+    auto *II = dyn_cast<llvm::IntrinsicInst>(&I);
+    if (II && llvm::isConvergenceControlIntrinsic(II->getIntrinsicID()))
+      return II;
+  }
+  return nullptr;
+}
+
+} // namespace
+
+llvm::CallBase *
+CodeGenFunction::addConvergenceControlToken(llvm::CallBase *Input,
+                                            llvm::Value *ParentToken) {
+  llvm::Value *bundleArgs[] = {ParentToken};
+  llvm::OperandBundleDef OB("convergencectrl", bundleArgs);
+  auto Output = llvm::CallBase::addOperandBundle(
+      Input, llvm::LLVMContext::OB_convergencectrl, OB, Input);
+  Input->replaceAllUsesWith(Output);
+  Input->eraseFromParent();
+  return Output;
+}
+
+llvm::IntrinsicInst *
+CodeGenFunction::emitConvergenceLoopToken(llvm::BasicBlock *BB,
+                                          llvm::Value *ParentToken) {
+  CGBuilderTy::InsertPoint IP = Builder.saveIP();
+
+  if (BB->empty())
+    Builder.SetInsertPoint(BB);
+  else
+    Builder.SetInsertPoint(&BB->front());
+
+  auto CB = Builder.CreateIntrinsic(
+      llvm::Intrinsic::experimental_convergence_loop, {}, {});
+  Builder.restoreIP(IP);
+
+  auto I = addConvergenceControlToken(CB, ParentToken);
+  return cast<llvm::IntrinsicInst>(I);
+}
+
+llvm::IntrinsicInst *
+CodeGenFunction::getOrEmitConvergenceEntryToken(llvm::Function *F) {
+  auto *BB = &F->getEntryBlock();
+  auto *token = getConvergenceToken(BB);
+  if (token)
+    return token;
+
+  // Adding a convergence token requires the function to be marked as
+  // convergent.
+  F->setConvergent();
+
+  CGBuilderTy::InsertPoint IP = Builder.saveIP();
+  Builder.SetInsertPoint(&BB->front());
+  auto I = Builder.CreateIntrinsic(
+      llvm::Intrinsic::experimental_convergence_entry, {}, {});
+  assert(isa<llvm::IntrinsicInst>(I));
+  Builder.restoreIP(IP);
+
+  return cast<llvm::IntrinsicInst>(I);
+}

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -353,6 +353,12 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
   assert(DeferredDeactivationCleanupStack.empty() &&
          "mismatched activate/deactivate of cleanups!");
 
+  if (getTarget().getTriple().isSPIRVLogical()) {
+    ConvergenceTokenStack.pop_back();
+    assert(ConvergenceTokenStack.empty() &&
+           "mismatched push/pop in convergence stack!");
+  }
+
   bool OnlySimpleReturnStmts = NumSimpleReturnExprs > 0
     && NumSimpleReturnExprs == NumReturnExprs
     && ReturnBlock.getBlock()->use_empty();
@@ -1277,6 +1283,9 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
   if (CurFuncDecl)
     if (const auto *VecWidth = CurFuncDecl->getAttr<MinVectorWidthAttr>())
       LargestVectorWidth = VecWidth->getVectorWidth();
+
+  if (getTarget().getTriple().isSPIRVLogical())
+    ConvergenceTokenStack.push_back(getOrEmitConvergenceEntryToken(CurFn));
 }
 
 void CodeGenFunction::EmitFunctionBody(const Stmt *Body) {

clang/lib/CodeGen/CodeGenFunction.h

@@ -315,6 +315,9 @@ class CodeGenFunction : public CodeGenTypeCache {
   /// Stack to track the Logical Operator recursion nest for MC/DC.
   SmallVector<const BinaryOperator *, 16> MCDCLogOpStack;
 
+  /// Stack to track the controlled convergence tokens.
+  SmallVector<llvm::IntrinsicInst *, 4> ConvergenceTokenStack;
+
   /// Number of nested loop to be consumed by the last surrounding
   /// loop-associated directive.
   int ExpectedOMPLoopDepth = 0;
@@ -5076,7 +5079,11 @@ class CodeGenFunction : public CodeGenTypeCache {
                                      const llvm::Twine &Name = "");
   // Adds a convergence_ctrl token to |Input| and emits the required parent
   // convergence instructions.
-  llvm::CallBase *addControlledConvergenceToken(llvm::CallBase *Input);
+  template <typename CallType>
+  CallType *addControlledConvergenceToken(CallType *Input) {
+    return dyn_cast<CallType>(
+        addConvergenceControlToken(Input, ConvergenceTokenStack.back()));
+  }
 
 private:
   // Emits a convergence_loop instruction for the given |BB|, with |ParentToken|

clang/test/CodeGenHLSL/builtins/RWBuffer-constructor.hlsl

@@ -1,4 +1,3 @@
-// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s
 // RUN: %clang_cc1 -triple spirv-vulkan-library -x hlsl -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=CHECK-SPIRV
 
 RWBuffer<float> Buf;