Revert "[HLSL] Adding Flatten and Branch if attributes (llvm#116331)"

This reverts commit 0d5c072.

Author: llvm-beanz

clang/include/clang/Basic/Attr.td

@@ -4335,16 +4335,6 @@ def HLSLLoopHint: StmtAttr {
   let Documentation = [HLSLLoopHintDocs, HLSLUnrollHintDocs];
 }
 
-def HLSLControlFlowHint: StmtAttr {
-  /// [branch]
-  /// [flatten]
-  let Spellings = [Microsoft<"branch">, Microsoft<"flatten">];
-  let Subjects = SubjectList<[IfStmt],
-                              ErrorDiag, "'if' statements">;
-  let LangOpts = [HLSL];
-  let Documentation = [InternalOnly];
-}
-
 def CapturedRecord : InheritableAttr {
   // This attribute has no spellings as it is only ever created implicitly.
   let Spellings = [];

clang/lib/CodeGen/CGStmt.cpp

@@ -757,8 +757,6 @@ void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
   bool noinline = false;
   bool alwaysinline = false;
   bool noconvergent = false;
-  HLSLControlFlowHintAttr::Spelling flattenOrBranch =
-      HLSLControlFlowHintAttr::SpellingNotCalculated;
   const CallExpr *musttail = nullptr;
 
   for (const auto *A : S.getAttrs()) {
@@ -790,17 +788,13 @@ void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
         Builder.CreateAssumption(AssumptionVal);
       }
     } break;
-    case attr::HLSLControlFlowHint: {
-      flattenOrBranch = cast<HLSLControlFlowHintAttr>(A)->getSemanticSpelling();
-    } break;
     }
   }
   SaveAndRestore save_nomerge(InNoMergeAttributedStmt, nomerge);
   SaveAndRestore save_noinline(InNoInlineAttributedStmt, noinline);
   SaveAndRestore save_alwaysinline(InAlwaysInlineAttributedStmt, alwaysinline);
   SaveAndRestore save_noconvergent(InNoConvergentAttributedStmt, noconvergent);
   SaveAndRestore save_musttail(MustTailCall, musttail);
-  SaveAndRestore save_flattenOrBranch(HLSLControlFlowAttr, flattenOrBranch);
   EmitStmt(S.getSubStmt(), S.getAttrs());
 }
 

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -40,7 +40,6 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/FPEnv.h"
-#include "llvm/IR/Instruction.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/MDBuilder.h"
@@ -2084,26 +2083,7 @@ void CodeGenFunction::EmitBranchOnBoolExpr(
     Weights = createProfileWeights(TrueCount, CurrentCount - TrueCount);
   }
 
-  llvm::Instruction *BrInst = Builder.CreateCondBr(CondV, TrueBlock, FalseBlock,
-                                                   Weights, Unpredictable);
-  switch (HLSLControlFlowAttr) {
-  case HLSLControlFlowHintAttr::Microsoft_branch:
-  case HLSLControlFlowHintAttr::Microsoft_flatten: {
-    llvm::MDBuilder MDHelper(CGM.getLLVMContext());
-
-    llvm::ConstantInt *BranchHintConstant =
-        HLSLControlFlowAttr ==
-                HLSLControlFlowHintAttr::Spelling::Microsoft_branch
-            ? llvm::ConstantInt::get(CGM.Int32Ty, 1)
-            : llvm::ConstantInt::get(CGM.Int32Ty, 2);
-
-    SmallVector<llvm::Metadata *, 2> Vals(
-        {MDHelper.createString("hlsl.controlflow.hint"),
-         MDHelper.createConstant(BranchHintConstant)});
-    BrInst->setMetadata("hlsl.controlflow.hint",
-                        llvm::MDNode::get(CGM.getLLVMContext(), Vals));
-  } break;
-  }
+  Builder.CreateCondBr(CondV, TrueBlock, FalseBlock, Weights, Unpredictable);
 }
 
 /// ErrorUnsupported - Print out an error that codegen doesn't support the

clang/lib/CodeGen/CodeGenFunction.h

@@ -615,10 +615,6 @@ class CodeGenFunction : public CodeGenTypeCache {
   /// True if the current statement has noconvergent attribute.
   bool InNoConvergentAttributedStmt = false;
 
-  /// HLSL Branch attribute.
-  HLSLControlFlowHintAttr::Spelling HLSLControlFlowAttr =
-      HLSLControlFlowHintAttr::SpellingNotCalculated;
-
   // The CallExpr within the current statement that the musttail attribute
   // applies to.  nullptr if there is no 'musttail' on the current statement.
   const CallExpr *MustTailCall = nullptr;

clang/lib/Sema/SemaStmtAttr.cpp

@@ -619,12 +619,6 @@ static Attr *handleHLSLLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
   return ::new (S.Context) HLSLLoopHintAttr(S.Context, A, UnrollFactor);
 }
 
-static Attr *handleHLSLControlFlowHint(Sema &S, Stmt *St, const ParsedAttr &A,
-                                       SourceRange Range) {
-
-  return ::new (S.Context) HLSLControlFlowHintAttr(S.Context, A);
-}
-
 static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
                                   SourceRange Range) {
   if (A.isInvalid() || A.getKind() == ParsedAttr::IgnoredAttribute)
@@ -661,8 +655,6 @@ static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
     return handleLoopHintAttr(S, St, A, Range);
   case ParsedAttr::AT_HLSLLoopHint:
     return handleHLSLLoopHintAttr(S, St, A, Range);
-  case ParsedAttr::AT_HLSLControlFlowHint:
-    return handleHLSLControlFlowHint(S, St, A, Range);
   case ParsedAttr::AT_OpenCLUnrollHint:
     return handleOpenCLUnrollHint(S, St, A, Range);
   case ParsedAttr::AT_Suppress:

clang/test/AST/HLSL/HLSLControlFlowHint.hlsl

@@ -33,7 +33,7 @@ let TargetPrefix = "spv" in {
   def int_spv_ptrcast : Intrinsic<[llvm_any_ty], [llvm_any_ty, llvm_metadata_ty, llvm_i32_ty], [ImmArg<ArgIndex<2>>]>;
   def int_spv_switch : Intrinsic<[], [llvm_any_ty, llvm_vararg_ty]>;
   def int_spv_loop_merge : Intrinsic<[], [llvm_vararg_ty]>;
-  def int_spv_selection_merge : Intrinsic<[], [llvm_any_ty, llvm_i32_ty], [ImmArg<ArgIndex<1>>]>;
+  def int_spv_selection_merge : Intrinsic<[], [llvm_vararg_ty]>;
   def int_spv_cmpxchg : Intrinsic<[llvm_i32_ty], [llvm_any_ty, llvm_vararg_ty]>;
   def int_spv_unreachable : Intrinsic<[], []>;
   def int_spv_alloca : Intrinsic<[llvm_any_ty], [llvm_i8_ty], [ImmArg<ArgIndex<0>>]>;

clang/test/CodeGenHLSL/HLSLControlFlowHint.hlsl

@@ -15,14 +15,12 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Analysis/DXILMetadataAnalysis.h"
 #include "llvm/Analysis/DXILResource.h"
-#include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/InitializePasses.h"
@@ -302,39 +300,6 @@ static MDTuple *emitTopLevelLibraryNode(Module &M, MDNode *RMD,
   return constructEntryMetadata(nullptr, nullptr, RMD, Properties, Ctx);
 }
 
-// TODO: We might need to refactor this to be more generic,
-// in case we need more metadata to be replaced.
-static void translateBranchMetadata(Module &M) {
-  for (Function &F : M) {
-    for (BasicBlock &BB : F) {
-      Instruction *BBTerminatorInst = BB.getTerminator();
-
-      MDNode *HlslControlFlowMD =
-          BBTerminatorInst->getMetadata("hlsl.controlflow.hint");
-
-      if (!HlslControlFlowMD)
-        continue;
-
-      assert(HlslControlFlowMD->getNumOperands() == 2 &&
-             "invalid operands for hlsl.controlflow.hint");
-
-      MDBuilder MDHelper(M.getContext());
-      ConstantInt *Op1 =
-          mdconst::extract<ConstantInt>(HlslControlFlowMD->getOperand(1));
-
-      SmallVector<llvm::Metadata *, 2> Vals(
-          ArrayRef<Metadata *>{MDHelper.createString("dx.controlflow.hints"),
-                               MDHelper.createConstant(Op1)});
-
-      MDNode *MDNode = llvm::MDNode::get(M.getContext(), Vals);
-
-      BBTerminatorInst->setMetadata("dx.controlflow.hints", MDNode);
-      BBTerminatorInst->setMetadata("hlsl.controlflow.hint", nullptr);
-    }
-    F.clearMetadata();
-  }
-}
-
 static void translateMetadata(Module &M, DXILBindingMap &DBM,
                               DXILResourceTypeMap &DRTM,
                               const Resources &MDResources,
@@ -407,7 +372,6 @@ PreservedAnalyses DXILTranslateMetadata::run(Module &M,
   const dxil::ModuleMetadataInfo MMDI = MAM.getResult<DXILMetadataAnalysis>(M);
 
   translateMetadata(M, DBM, DRTM, MDResources, ShaderFlags, MMDI);
-  translateBranchMetadata(M);
 
   return PreservedAnalyses::all();
 }
@@ -445,7 +409,6 @@ class DXILTranslateMetadataLegacy : public ModulePass {
         getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
 
     translateMetadata(M, DBM, DRTM, MDResources, ShaderFlags, MMDI);
-    translateBranchMetadata(M);
     return true;
   }
 };

llvm/include/llvm/IR/IntrinsicsSPIRV.td

@@ -33,7 +33,6 @@
 #include "llvm/CodeGen/TargetOpcodes.h"
 #include "llvm/IR/IntrinsicsSPIRV.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
 
 #define DEBUG_TYPE "spirv-isel"
 
@@ -46,17 +45,6 @@ using ExtInstList =
 
 namespace {
 
-llvm::SPIRV::SelectionControl::SelectionControl
-getSelectionOperandForImm(int Imm) {
-  if (Imm == 2)
-    return SPIRV::SelectionControl::Flatten;
-  if (Imm == 1)
-    return SPIRV::SelectionControl::DontFlatten;
-  if (Imm == 0)
-    return SPIRV::SelectionControl::None;
-  llvm_unreachable("Invalid immediate");
-}
-
 #define GET_GLOBALISEL_PREDICATE_BITSET
 #include "SPIRVGenGlobalISel.inc"
 #undef GET_GLOBALISEL_PREDICATE_BITSET
@@ -2830,24 +2818,19 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
     }
     return MIB.constrainAllUses(TII, TRI, RBI);
   }
-  case Intrinsic::spv_loop_merge: {
-    auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpLoopMerge));
+  case Intrinsic::spv_loop_merge:
+  case Intrinsic::spv_selection_merge: {
+    const auto Opcode = IID == Intrinsic::spv_selection_merge
+                            ? SPIRV::OpSelectionMerge
+                            : SPIRV::OpLoopMerge;
+    auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(Opcode));
     for (unsigned i = 1; i < I.getNumExplicitOperands(); ++i) {
       assert(I.getOperand(i).isMBB());
       MIB.addMBB(I.getOperand(i).getMBB());
     }
     MIB.addImm(SPIRV::SelectionControl::None);
     return MIB.constrainAllUses(TII, TRI, RBI);
   }
-  case Intrinsic::spv_selection_merge: {
-    auto MIB =
-        BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpSelectionMerge));
-    assert(I.getOperand(1).isMBB() &&
-           "operand 1 to spv_selection_merge must be a basic block");
-    MIB.addMBB(I.getOperand(1).getMBB());
-    MIB.addImm(getSelectionOperandForImm(I.getOperand(2).getImm()));
-    return MIB.constrainAllUses(TII, TRI, RBI);
-  }
   case Intrinsic::spv_cmpxchg:
     return selectAtomicCmpXchg(ResVReg, ResType, I);
   case Intrinsic::spv_unreachable: