[NFC][DirectX] Refactor DXILPrepare/DXILTranslateMetadata (llvm#164285)

This pr updates `DXILPrepare` and `DXILTranslateMetadata` by moving all
the removal of metadata from `DXILPrepare` to `DXILTranslateMetadata` to
have a more consistent definition of what each pass is doing.

It restricts the `DXILPrepare` to only update function attributes and
insert bitcasts, and moves the removal of metadata to
`DXILTranslateMetadata` so that all manipulation of metadata is done in
a single pass.

Author: inbelic

llvm/docs/DirectX/DXILArchitecture.rst

@@ -118,9 +118,10 @@ The passes to generate DXIL IR follow the flow:
 Each of these passes has a defined responsibility:
 
 #. DXILOpLowering translates LLVM intrinsic calls to dx.op calls.
-#. DXILPrepare transforms the DXIL IR to be compatible with LLVM 3.7, and
-   inserts bitcasts to allow typed pointers to be inserted.
-#. DXILTranslateMetadata emits the DXIL Metadata structures.
+#. DXILPrepare updates functions in the DXIL IR to be compatible with LLVM 3.7,
+   namely removing attributes, and inserting bitcasts to allow typed pointers
+   to be inserted.
+#. DXILTranslateMetadata transforms and emits all recognized DXIL Metadata.
 
 The passes to encode DXIL to binary in the DX Container follow the flow:
 

llvm/lib/Target/DirectX/DXILPrepare.cpp

@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 ///
-/// \file This file contains pases and utilities to convert a modern LLVM
+/// \file This file contains passes and utilities to convert a modern LLVM
 /// module into a module compatible with the LLVM 3.7-based DirectX Intermediate
 /// Language (DXIL).
 //===----------------------------------------------------------------------===//
@@ -16,7 +16,6 @@
 #include "DirectX.h"
 #include "DirectXIRPasses/PointerTypeAnalysis.h"
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Analysis/DXILMetadataAnalysis.h"
 #include "llvm/Analysis/DXILResource.h"
@@ -27,7 +26,6 @@
 #include "llvm/IR/Module.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
-#include "llvm/Support/Compiler.h"
 #include "llvm/Support/VersionTuple.h"
 
 #define DEBUG_TYPE "dxil-prepare"
@@ -116,31 +114,6 @@ static void removeStringFunctionAttributes(Function &F,
   F.removeRetAttrs(DeadAttrs);
 }
 
-static void cleanModuleFlags(Module &M) {
-  NamedMDNode *MDFlags = M.getModuleFlagsMetadata();
-  if (!MDFlags)
-    return;
-
-  SmallVector<llvm::Module::ModuleFlagEntry> FlagEntries;
-  M.getModuleFlagsMetadata(FlagEntries);
-  bool Updated = false;
-  for (auto &Flag : FlagEntries) {
-    // llvm 3.7 only supports behavior up to AppendUnique.
-    if (Flag.Behavior <= Module::ModFlagBehavior::AppendUnique)
-      continue;
-    Flag.Behavior = Module::ModFlagBehavior::Warning;
-    Updated = true;
-  }
-
-  if (!Updated)
-    return;
-
-  MDFlags->eraseFromParent();
-
-  for (auto &Flag : FlagEntries)
-    M.addModuleFlag(Flag.Behavior, Flag.Key->getString(), Flag.Val);
-}
-
 class DXILPrepareModule : public ModulePass {
 
   static Value *maybeGenerateBitcast(IRBuilder<> &Builder,
@@ -202,15 +175,6 @@ class DXILPrepareModule : public ModulePass {
                          Builder.getPtrTy(PtrTy->getAddressSpace())));
   }
 
-  static std::array<unsigned, 6> getCompatibleInstructionMDs(llvm::Module &M) {
-    return {M.getMDKindID("dx.nonuniform"),
-            M.getMDKindID("dx.controlflow.hints"),
-            M.getMDKindID("dx.precise"),
-            llvm::LLVMContext::MD_range,
-            llvm::LLVMContext::MD_alias_scope,
-            llvm::LLVMContext::MD_noalias};
-  }
-
 public:
   bool runOnModule(Module &M) override {
     PointerTypeMap PointerTypes = PointerTypeAnalysis::run(M);
@@ -224,30 +188,33 @@ class DXILPrepareModule : public ModulePass {
     const dxil::ModuleMetadataInfo MetadataInfo =
         getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
     VersionTuple ValVer = MetadataInfo.ValidatorVersion;
-    bool SkipValidation = ValVer.getMajor() == 0 && ValVer.getMinor() == 0;
-
-    // construct allowlist of valid metadata node kinds
-    std::array<unsigned, 6> DXILCompatibleMDs = getCompatibleInstructionMDs(M);
+    bool AllowExperimental = ValVer.getMajor() == 0 && ValVer.getMinor() == 0;
 
     for (auto &F : M.functions()) {
       F.removeFnAttrs(AttrMask);
       F.removeRetAttrs(AttrMask);
       // Only remove string attributes if we are not skipping validation.
       // This will reserve the experimental attributes when validation version
       // is 0.0 for experiment mode.
-      removeStringFunctionAttributes(F, SkipValidation);
+      removeStringFunctionAttributes(F, AllowExperimental);
       for (size_t Idx = 0, End = F.arg_size(); Idx < End; ++Idx)
         F.removeParamAttrs(Idx, AttrMask);
 
       for (auto &BB : F) {
         IRBuilder<> Builder(&BB);
         for (auto &I : make_early_inc_range(BB)) {
 
-          I.dropUnknownNonDebugMetadata(DXILCompatibleMDs);
+          if (auto *CB = dyn_cast<CallBase>(&I)) {
+            CB->removeFnAttrs(AttrMask);
+            CB->removeRetAttrs(AttrMask);
+            for (size_t Idx = 0, End = CB->arg_size(); Idx < End; ++Idx)
+              CB->removeParamAttrs(Idx, AttrMask);
+            continue;
+          }
 
           // Emtting NoOp bitcast instructions allows the ValueEnumerator to be
           // unmodified as it reserves instruction IDs during contruction.
-          if (auto LI = dyn_cast<LoadInst>(&I)) {
+          if (auto *LI = dyn_cast<LoadInst>(&I)) {
             if (Value *NoOpBitcast = maybeGenerateBitcast(
                     Builder, PointerTypes, I, LI->getPointerOperand(),
                     LI->getType())) {
@@ -257,7 +224,7 @@ class DXILPrepareModule : public ModulePass {
             }
             continue;
           }
-          if (auto SI = dyn_cast<StoreInst>(&I)) {
+          if (auto *SI = dyn_cast<StoreInst>(&I)) {
             if (Value *NoOpBitcast = maybeGenerateBitcast(
                     Builder, PointerTypes, I, SI->getPointerOperand(),
                     SI->getValueOperand()->getType())) {
@@ -268,51 +235,28 @@ class DXILPrepareModule : public ModulePass {
             }
             continue;
           }
-          if (auto GEP = dyn_cast<GetElementPtrInst>(&I)) {
+          if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
             if (Value *NoOpBitcast = maybeGenerateBitcast(
                     Builder, PointerTypes, I, GEP->getPointerOperand(),
                     GEP->getSourceElementType()))
               GEP->setOperand(0, NoOpBitcast);
             continue;
           }
-          if (auto *CB = dyn_cast<CallBase>(&I)) {
-            CB->removeFnAttrs(AttrMask);
-            CB->removeRetAttrs(AttrMask);
-            for (size_t Idx = 0, End = CB->arg_size(); Idx < End; ++Idx)
-              CB->removeParamAttrs(Idx, AttrMask);
-            continue;
-          }
         }
       }
     }
-    // Remove flags not for DXIL.
-    cleanModuleFlags(M);
-
-    // dx.rootsignatures will have been parsed from its metadata form as its
-    // binary form as part of the RootSignatureAnalysisWrapper, so safely
-    // remove it as it is not recognized in DXIL
-    if (NamedMDNode *RootSignature = M.getNamedMetadata("dx.rootsignatures"))
-      RootSignature->eraseFromParent();
-
-    // llvm.errno.tbaa was recently added but is not supported in LLVM 3.7 and
-    // causes all tests using the DXIL Validator to fail.
-    //
-    // This is a temporary fix and should be replaced with a whitelist once
-    // we have determined all metadata that the DXIL Validator allows
-    if (NamedMDNode *ErrNo = M.getNamedMetadata("llvm.errno.tbaa"))
-      ErrNo->eraseFromParent();
 
     return true;
   }
 
   DXILPrepareModule() : ModulePass(ID) {}
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<DXILMetadataAnalysisWrapperPass>();
-    AU.addRequired<RootSignatureAnalysisWrapper>();
-    AU.addPreserved<RootSignatureAnalysisWrapper>();
-    AU.addPreserved<ShaderFlagsAnalysisWrapper>();
+
     AU.addPreserved<DXILMetadataAnalysisWrapperPass>();
     AU.addPreserved<DXILResourceWrapperPass>();
+    AU.addPreserved<RootSignatureAnalysisWrapper>();
+    AU.addPreserved<ShaderFlagsAnalysisWrapper>();
   }
   static char ID; // Pass identification.
 };
@@ -323,7 +267,6 @@ char DXILPrepareModule::ID = 0;
 INITIALIZE_PASS_BEGIN(DXILPrepareModule, DEBUG_TYPE, "DXIL Prepare Module",
                       false, false)
 INITIALIZE_PASS_DEPENDENCY(DXILMetadataAnalysisWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(RootSignatureAnalysisWrapper)
 INITIALIZE_PASS_END(DXILPrepareModule, DEBUG_TYPE, "DXIL Prepare Module", false,
                     false)