[SPIR-V] Generalize/simplify generating bitcasts for ptr kernel args

Author: michalpaszkowski

llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp

@@ -290,25 +290,14 @@ void SPIRVEmitIntrinsics::insertPtrCastInstr(Instruction *I) {
   Value *Pointer;
   Type *ExpectedElementType;
   unsigned OperandToReplace;
-  bool AllowCastingToChar = false;
 
   StoreInst *SI = dyn_cast<StoreInst>(I);
   if (SI && F->getCallingConv() == CallingConv::SPIR_KERNEL &&
       SI->getValueOperand()->getType()->isPointerTy() &&
       isa<Argument>(SI->getValueOperand())) {
-    Argument *Arg = cast<Argument>(SI->getValueOperand());
-    MDString *ArgType = getOCLKernelArgType(*Arg->getParent(), Arg->getArgNo());
-    if (!ArgType || ArgType->getString().starts_with("uchar*"))
-      return;
-
-    // Handle special case when StoreInst's value operand is a kernel argument
-    // of a pointer type. Since these arguments could have either a basic
-    // element type (e.g. float*) or OpenCL builtin type (sampler_t), bitcast
-    // the StoreInst's value operand to default pointer element type (i8).
-    Pointer = Arg;
+    Pointer = SI->getValueOperand();
     ExpectedElementType = IntegerType::getInt8Ty(F->getContext());
     OperandToReplace = 0;
-    AllowCastingToChar = true;
   } else if (SI) {
     Pointer = SI->getPointerOperand();
     ExpectedElementType = SI->getValueOperand()->getType();
@@ -390,10 +379,20 @@ void SPIRVEmitIntrinsics::insertPtrCastInstr(Instruction *I) {
   }
 
   // Do not emit spv_ptrcast if it would cast to the default pointer element
-  // type (i8) of the same address space.
-  if (ExpectedElementType->isIntegerTy(8) && !AllowCastingToChar)
+  // type (i8) of the same address space. In case of OpenCL kernels, make sure
+  // i8 is the pointer element type defined for the given kernel argument.
+  if (ExpectedElementType->isIntegerTy(8) &&
+      F->getCallingConv() != CallingConv::SPIR_KERNEL)
     return;
 
+  Argument *Arg = dyn_cast<Argument>(Pointer);
+  if (ExpectedElementType->isIntegerTy(8) &&
+      F->getCallingConv() == CallingConv::SPIR_KERNEL && Arg) {
+    MDString *ArgType = getOCLKernelArgType(*Arg->getParent(), Arg->getArgNo());
+    if (ArgType && ArgType->getString().starts_with("uchar*"))
+      return;
+  }
+
   // If this would be the first spv_ptrcast, the pointer's defining instruction
   // requires spv_assign_ptr_type and does not already have one, do not emit
   // spv_ptrcast and emit spv_assign_ptr_type instead.

llvm/test/CodeGen/SPIRV/pointers/getelementptr-kernel-arg-char.ll

@@ -0,0 +1,31 @@
+
+; RUN: llc -O0 -mtriple=spirv64-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv64-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; CHECK-DAG: %[[#INT8:]] = OpTypeInt 8 0
+; CHECK-DAG: %[[#INT64:]] = OpTypeInt 64 0
+; CHECK-DAG: %[[#VINT8:]] = OpTypeVector %[[#INT8]] 2
+; CHECK-DAG: %[[#PTRINT8:]] = OpTypePointer Workgroup %[[#INT8]]
+; CHECK-DAG: %[[#PTRVINT8:]] = OpTypePointer Workgroup %[[#VINT8]]
+; CHECK-DAG: %[[#CONST:]] = OpConstant %[[#INT64]] 1
+
+; CHECK: %[[#PARAM1:]] = OpFunctionParameter %[[#PTRVINT8]]
+define spir_kernel void @test1(ptr addrspace(3) %address) !kernel_arg_type !1 {
+; CHECK: %[[#BITCAST1:]] = OpBitcast %[[#PTRINT8]] %[[#PARAM1]]
+; CHECK: %[[#]] = OpInBoundsPtrAccessChain %[[#PTRINT8]] %[[#BITCAST1]] %[[#CONST]]
+  %cast = bitcast ptr addrspace(3) %address to ptr addrspace(3)
+  %gep = getelementptr inbounds i8, ptr addrspace(3) %cast, i64 1
+  ret void
+}
+
+; CHECK: %[[#PARAM2:]] = OpFunctionParameter %[[#PTRVINT8]]
+define spir_kernel void @test2(ptr addrspace(3) %address) !kernel_arg_type !1 {
+; CHECK: %[[#BITCAST2:]] = OpBitcast %[[#PTRINT8]] %[[#PARAM2]]
+; CHECK: %[[#]] = OpInBoundsPtrAccessChain %[[#PTRINT8]] %[[#BITCAST2]] %[[#CONST]]
+  %gep = getelementptr inbounds i8, ptr addrspace(3) %address, i64 1
+  ret void
+}
+
+declare spir_func <2 x i8> @_Z6vload2mPU3AS3Kc(i64, ptr addrspace(3))
+
+!1 = !{!"char2*"}