[DirectX] Legalize llvm.lifetime.* intrinsics in EmbedDXILPass

llvm/lib/Target/DirectX/DXILShaderFlags.cpp

@@ -152,7 +152,7 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
   if (!CSF.Int64Ops)
     CSF.Int64Ops = I.getType()->isIntegerTy(64);
 
-  if (!CSF.Int64Ops) {
+  if (!CSF.Int64Ops && !isa<LifetimeIntrinsic>(&I)) {
     for (const Value *Op : I.operands()) {
       if (Op->getType()->isIntegerTy(64)) {
         CSF.Int64Ops = true;

llvm/lib/Target/DirectX/DXILWriter/DXILWriterPass.cpp

@@ -17,6 +17,7 @@
 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/InitializePasses.h"
@@ -52,6 +53,51 @@ class WriteDXILPass : public llvm::ModulePass {
   }
 };
 
+static void legalizeLifetimeIntrinsics(Module &M) {
+  for (Function &F : M) {
+    Intrinsic::ID IID = F.getIntrinsicID();
+    if (IID != Intrinsic::lifetime_start && IID != Intrinsic::lifetime_end)
+      continue;
+
+    // Lifetime intrinsics in LLVM 3.7 do not have the memory FnAttr
+    F.removeFnAttr(Attribute::Memory);
+
+    // Lifetime intrinsics in LLVM 3.7 do not have mangled names
+    F.setName(Intrinsic::getBaseName(IID));
+
+    // LLVM 3.7 Lifetime intrinics require an i8* operand, so we insert bitcasts
+    // to ensure that is the case
+    for (auto *User : make_early_inc_range(F.users())) {
+      CallInst *CI = dyn_cast<CallInst>(User);
+      assert(CI && "Expected user of a lifetime intrinsic function to be a "
+                   "lifetime intrinsic call");
+      Value *PtrOperand = CI->getArgOperand(1);
+      PointerType *PtrTy = cast<PointerType>(PtrOperand->getType());
+      Value *NoOpBitCast = CastInst::Create(Instruction::BitCast, PtrOperand,
+                                            PtrTy, "", CI->getIterator());
+      CI->setArgOperand(1, NoOpBitCast);
+    }
+  }
+}
+
+static void removeLifetimeIntrinsics(Module &M) {
+  for (Function &F : make_early_inc_range(M))
+    if (Intrinsic::ID IID = F.getIntrinsicID();
+        IID == Intrinsic::lifetime_start || IID == Intrinsic::lifetime_end) {
+      for (User *U : make_early_inc_range(F.users())) {
+        LifetimeIntrinsic *LI = dyn_cast<LifetimeIntrinsic>(U);
+        assert(LI && "Expected user of lifetime intrinsic function to be "
+                     "a LifetimeIntrinsic instruction");
+        BitCastInst *BCI = dyn_cast<BitCastInst>(LI->getArgOperand(1));
+        assert(BCI && "Expected pointer operand of LifetimeIntrinsic to be a "
+                      "BitCastInst");
+        LI->eraseFromParent();
+        BCI->eraseFromParent();
+      }
+      F.eraseFromParent();
+    }
+}
+
 class EmbedDXILPass : public llvm::ModulePass {
 public:
   static char ID; // Pass identification, replacement for typeid
@@ -70,8 +116,17 @@ class EmbedDXILPass : public llvm::ModulePass {
     // Only the output bitcode need to be DXIL triple.
     M.setTargetTriple(Triple("dxil-ms-dx"));
 
+    // Perform late legalization of lifetime intrinsics that would otherwise
+    // fail the Module Verifier if performed in an earlier pass
+    legalizeLifetimeIntrinsics(M);
+
     WriteDXILToFile(M, OS);
 
+    // We no longer need lifetime intrinsics after bitcode serialization, so we
+    // simply remove them to keep the Module Verifier happy after our
+    // not-so-legal legalizations
+    removeLifetimeIntrinsics(M);
+
     // Recover triple.
     M.setTargetTriple(OriginalTriple);
 

llvm/test/CodeGen/DirectX/ShaderFlags/lifetimes-noint64op.ll

@@ -0,0 +1,36 @@
+; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+; RUN: llc %s --filetype=obj -o - | obj2yaml | FileCheck %s --check-prefix=DXC
+
+target triple = "dxil-pc-shadermodel6.7-library"
+
+; CHECK: ; Combined Shader Flags for Module
+; CHECK-NEXT: ; Shader Flags Value: 0x00000000
+; CHECK-NEXT: ;
+; CHECK-NOT:  ; Note: shader requires additional functionality:
+; CHECK-NOT:  ;       64-Bit integer
+; CHECK-NOT:  ; Note: extra DXIL module flags:
+; CHECK-NOT:  ;
+; CHECK-NEXT: ; Shader Flags for Module Functions
+; CHECK-NEXT: ; Function lifetimes : 0x00000000
+
+define void @lifetimes() #0 {
+  %a = alloca [4 x i32], align 8
+  call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %a)
+  call void @llvm.lifetime.end.p0(i64 16, ptr nonnull %a)
+  ret void
+}
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.start.p0(i64, ptr) #1
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.end.p0(i64, ptr) #1
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
+attributes #1 = { nounwind memory(argmem: readwrite) }
+
+; DXC: - Name:            SFI0
+; DXC-NEXT:     Size:            8
+; DXC-NOT:     Flags:
+; DXC-NOT:         Int64Ops:        true
+; DXC: ...

llvm/test/tools/dxil-dis/lifetimes.ll

@@ -0,0 +1,38 @@
+; RUN: llc --filetype=obj %s -o - | dxil-dis -o - | FileCheck %s
+target triple = "dxil-unknown-shadermodel6.7-library"
+
+define void @test_lifetimes()  {
+; CHECK-LABEL: test_lifetimes
+; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x i32], align 4
+; CHECK-NEXT: [[GEP:%.*]] = getelementptr [2 x i32], [2 x i32]* [[ALLOCA]], i32 0, i32 0
+; CHECK-NEXT: [[BITCAST:%.*]] = bitcast [2 x i32]* [[ALLOCA]] to i8*
+; CHECK-NEXT: call void @llvm.lifetime.start(i64 4, i8* nonnull [[BITCAST]])
+; CHECK-NEXT: store i32 0, i32* [[GEP]], align 4
+; CHECK-NEXT: [[BITCAST:%.*]] = bitcast [2 x i32]* [[ALLOCA]] to i8*
+; CHECK-NEXT: call void @llvm.lifetime.end(i64 4, i8* nonnull [[BITCAST]])
+; CHECK-NEXT: ret void
+;
+  %a = alloca [2 x i32], align 4
+  %gep = getelementptr [2 x i32], ptr %a, i32 0, i32 0
+  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %a)
+  store i32 0, ptr %gep, align 4
+  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %a)
+  ret void
+}
+
+; CHECK-DAG: attributes [[LIFETIME_ATTRS:#.*]] = { nounwind }
+
+; CHECK-DAG: ; Function Attrs: nounwind
+; CHECK-DAG: declare void @llvm.lifetime.start(i64, i8* nocapture) [[LIFETIME_ATTRS]]
+
+; CHECK-DAG: ; Function Attrs: nounwind
+; CHECK-DAG: declare void @llvm.lifetime.end(i64, i8* nocapture) [[LIFETIME_ATTRS]]
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.end.p0(i64, ptr) #0
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.start.p0(i64, ptr) #0
+
+attributes #0 = { nounwind memory(argmem: readwrite) }
+