[clang] fb90733 - [HLSL] implement elementwise firstbithigh hlsl builtin (#111082)

via cfe-commits cfe-commits at lists.llvm.org
Wed Nov 6 07:31:44 PST 2024


Author: Sarah Spall
Date: 2024-11-06T07:31:39-08:00
New Revision: fb90733e196039b0a77f43af98c42c9267a31e07

URL: https://github.com/llvm/llvm-project/commit/fb90733e196039b0a77f43af98c42c9267a31e07
DIFF: https://github.com/llvm/llvm-project/commit/fb90733e196039b0a77f43af98c42c9267a31e07.diff

LOG: [HLSL] implement elementwise firstbithigh hlsl builtin (#111082)

Implements elementwise firstbithigh hlsl builtin.
Implements firstbituhigh intrinsic for spirv and directx, which handles
unsigned integers
Implements firstbitshigh intrinsic for spirv and directx, which handles
signed integers.
Fixes #113486
Closes #99115

Added: 
    clang/test/CodeGenHLSL/builtins/firstbithigh.hlsl
    clang/test/SemaHLSL/BuiltIns/firstbithigh-errors.hlsl
    llvm/test/CodeGen/DirectX/firstbithigh.ll
    llvm/test/CodeGen/DirectX/firstbitshigh_error.ll
    llvm/test/CodeGen/DirectX/firstbituhigh_error.ll
    llvm/test/CodeGen/SPIRV/hlsl-intrinsics/firstbithigh.ll

Modified: 
    clang/include/clang/Basic/Builtins.td
    clang/lib/CodeGen/CGBuiltin.cpp
    clang/lib/CodeGen/CGHLSLRuntime.h
    clang/lib/Headers/hlsl/hlsl_intrinsics.h
    clang/lib/Sema/SemaHLSL.cpp
    llvm/include/llvm/IR/IntrinsicsDirectX.td
    llvm/include/llvm/IR/IntrinsicsSPIRV.td
    llvm/lib/Target/DirectX/DXIL.td
    llvm/lib/Target/DirectX/DirectXTargetTransformInfo.cpp
    llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
    llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index f5d45fa7b90a40..87a798183d6e19 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -4798,6 +4798,12 @@ def HLSLDot4AddI8Packed : LangBuiltin<"HLSL_LANG"> {
   let Prototype = "int(unsigned int, unsigned int, int)";
 }
 
+def HLSLFirstBitHigh : LangBuiltin<"HLSL_LANG"> {
+  let Spellings = ["__builtin_hlsl_elementwise_firstbithigh"];
+  let Attributes = [NoThrow, Const];
+  let Prototype = "void(...)";
+}
+
 def HLSLFrac : LangBuiltin<"HLSL_LANG"> {
   let Spellings = ["__builtin_hlsl_elementwise_frac"];
   let Attributes = [NoThrow, Const];

diff  --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 82770a75af23e4..5c3df5124517d6 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -18773,6 +18773,15 @@ static Intrinsic::ID getDotProductIntrinsic(CGHLSLRuntime &RT, QualType QT) {
   return RT.getUDotIntrinsic();
 }
 
+Intrinsic::ID getFirstBitHighIntrinsic(CGHLSLRuntime &RT, QualType QT) {
+  if (QT->hasSignedIntegerRepresentation()) {
+    return RT.getFirstBitSHighIntrinsic();
+  }
+
+  assert(QT->hasUnsignedIntegerRepresentation());
+  return RT.getFirstBitUHighIntrinsic();
+}
+
 Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
                                             const CallExpr *E,
                                             ReturnValueSlot ReturnValue) {
@@ -18872,6 +18881,15 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
         /*ReturnType=*/C->getType(), ID, ArrayRef<Value *>{A, B, C}, nullptr,
         "hlsl.dot4add.i8packed");
   }
+  case Builtin::BI__builtin_hlsl_elementwise_firstbithigh: {
+
+    Value *X = EmitScalarExpr(E->getArg(0));
+
+    return Builder.CreateIntrinsic(
+        /*ReturnType=*/ConvertType(E->getType()),
+        getFirstBitHighIntrinsic(CGM.getHLSLRuntime(), E->getArg(0)->getType()),
+        ArrayRef<Value *>{X}, nullptr, "hlsl.firstbithigh");
+  }
   case Builtin::BI__builtin_hlsl_lerp: {
     Value *X = EmitScalarExpr(E->getArg(0));
     Value *Y = EmitScalarExpr(E->getArg(1));

diff  --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index 5e09ab694a79b8..ff810cc535c087 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -92,6 +92,8 @@ class CGHLSLRuntime {
   GENERATE_HLSL_INTRINSIC_FUNCTION(Dot4AddI8Packed, dot4add_i8packed)
   GENERATE_HLSL_INTRINSIC_FUNCTION(WaveIsFirstLane, wave_is_first_lane)
   GENERATE_HLSL_INTRINSIC_FUNCTION(WaveReadLaneAt, wave_readlane)
+  GENERATE_HLSL_INTRINSIC_FUNCTION(FirstBitUHigh, firstbituhigh)
+  GENERATE_HLSL_INTRINSIC_FUNCTION(FirstBitSHigh, firstbitshigh)
 
   GENERATE_HLSL_INTRINSIC_FUNCTION(CreateHandleFromBinding, handle_fromBinding)
 

diff  --git a/clang/lib/Headers/hlsl/hlsl_intrinsics.h b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
index 6cd93c5e9a592d..12d3aa418449c0 100644
--- a/clang/lib/Headers/hlsl/hlsl_intrinsics.h
+++ b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
@@ -1008,6 +1008,78 @@ float3 exp2(float3);
 _HLSL_BUILTIN_ALIAS(__builtin_elementwise_exp2)
 float4 exp2(float4);
 
+//===----------------------------------------------------------------------===//
+// firstbithigh builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn T firstbithigh(T Val)
+/// \brief Returns the location of the first set bit starting from the highest
+/// order bit and working downward, per component.
+/// \param Val the input value.
+
+#ifdef __HLSL_ENABLE_16_BIT
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint firstbithigh(int16_t);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint2 firstbithigh(int16_t2);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint3 firstbithigh(int16_t3);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint4 firstbithigh(int16_t4);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint firstbithigh(uint16_t);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint2 firstbithigh(uint16_t2);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint3 firstbithigh(uint16_t3);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint4 firstbithigh(uint16_t4);
+#endif
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint firstbithigh(int);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint2 firstbithigh(int2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint3 firstbithigh(int3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint4 firstbithigh(int4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint firstbithigh(uint);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint2 firstbithigh(uint2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint3 firstbithigh(uint3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint4 firstbithigh(uint4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint firstbithigh(int64_t);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint2 firstbithigh(int64_t2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint3 firstbithigh(int64_t3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint4 firstbithigh(int64_t4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint firstbithigh(uint64_t);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint2 firstbithigh(uint64_t2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint3 firstbithigh(uint64_t3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_firstbithigh)
+uint4 firstbithigh(uint64_t4);
+
 //===----------------------------------------------------------------------===//
 // floor builtins
 //===----------------------------------------------------------------------===//

diff  --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
index 298b7ad4f9e687..65b0d9cd65637f 100644
--- a/clang/lib/Sema/SemaHLSL.cpp
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -1947,6 +1947,31 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
       return true;
     break;
   }
+  case Builtin::BI__builtin_hlsl_elementwise_firstbithigh: {
+    if (SemaRef.PrepareBuiltinElementwiseMathOneArgCall(TheCall))
+      return true;
+
+    const Expr *Arg = TheCall->getArg(0);
+    QualType ArgTy = Arg->getType();
+    QualType EltTy = ArgTy;
+
+    QualType ResTy = SemaRef.Context.UnsignedIntTy;
+
+    if (auto *VecTy = EltTy->getAs<VectorType>()) {
+      EltTy = VecTy->getElementType();
+      ResTy = SemaRef.Context.getVectorType(ResTy, VecTy->getNumElements(),
+                                            VecTy->getVectorKind());
+    }
+
+    if (!EltTy->isIntegerType()) {
+      Diag(Arg->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << 1 << /* integer ty */ 6 << ArgTy;
+      return true;
+    }
+
+    TheCall->setType(ResTy);
+    break;
+  }
   case Builtin::BI__builtin_hlsl_select: {
     if (SemaRef.checkArgCount(TheCall, 3))
       return true;

diff  --git a/clang/test/CodeGenHLSL/builtins/firstbithigh.hlsl b/clang/test/CodeGenHLSL/builtins/firstbithigh.hlsl
new file mode 100644
index 00000000000000..debf6b6d3e3f5a
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/firstbithigh.hlsl
@@ -0,0 +1,153 @@
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type \
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s -DTARGET=dx
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   spirv-unknown-vulkan-compute %s -fnative-half-type \
+// RUN: -emit-llvm -disable-llvm-passes \
+// RUN:   -o - | FileCheck %s -DTARGET=spv
+
+#ifdef __HLSL_ENABLE_16_BIT
+// CHECK-LABEL: test_firstbithigh_ushort
+// CHECK: call i32 @llvm.[[TARGET]].firstbituhigh.i16
+uint test_firstbithigh_ushort(uint16_t p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ushort2
+// CHECK: call <2 x i32> @llvm.[[TARGET]].firstbituhigh.v2i16
+uint2 test_firstbithigh_ushort2(uint16_t2 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ushort3
+// CHECK: call <3 x i32> @llvm.[[TARGET]].firstbituhigh.v3i16
+uint3 test_firstbithigh_ushort3(uint16_t3 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ushort4
+// CHECK: call <4 x i32> @llvm.[[TARGET]].firstbituhigh.v4i16
+uint4 test_firstbithigh_ushort4(uint16_t4 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_short
+// CHECK: call i32 @llvm.[[TARGET]].firstbitshigh.i16
+uint test_firstbithigh_short(int16_t p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_short2
+// CHECK: call <2 x i32> @llvm.[[TARGET]].firstbitshigh.v2i16
+uint2 test_firstbithigh_short2(int16_t2 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_short3
+// CHECK: call <3 x i32> @llvm.[[TARGET]].firstbitshigh.v3i16
+uint3 test_firstbithigh_short3(int16_t3 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_short4
+// CHECK: call <4 x i32> @llvm.[[TARGET]].firstbitshigh.v4i16
+uint4 test_firstbithigh_short4(int16_t4 p0) {
+  return firstbithigh(p0);
+}
+#endif // __HLSL_ENABLE_16_BIT
+
+// CHECK-LABEL: test_firstbithigh_uint
+// CHECK: call i32 @llvm.[[TARGET]].firstbituhigh.i32
+uint test_firstbithigh_uint(uint p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_uint2
+// CHECK: call <2 x i32> @llvm.[[TARGET]].firstbituhigh.v2i32
+uint2 test_firstbithigh_uint2(uint2 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_uint3
+// CHECK: call <3 x i32> @llvm.[[TARGET]].firstbituhigh.v3i32
+uint3 test_firstbithigh_uint3(uint3 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_uint4
+// CHECK: call <4 x i32> @llvm.[[TARGET]].firstbituhigh.v4i32
+uint4 test_firstbithigh_uint4(uint4 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ulong
+// CHECK: call i32 @llvm.[[TARGET]].firstbituhigh.i64
+uint test_firstbithigh_ulong(uint64_t p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ulong2
+// CHECK: call <2 x i32> @llvm.[[TARGET]].firstbituhigh.v2i64
+uint2 test_firstbithigh_ulong2(uint64_t2 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ulong3
+// CHECK: call <3 x i32> @llvm.[[TARGET]].firstbituhigh.v3i64
+uint3 test_firstbithigh_ulong3(uint64_t3 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_ulong4
+// CHECK: call <4 x i32> @llvm.[[TARGET]].firstbituhigh.v4i64
+uint4 test_firstbithigh_ulong4(uint64_t4 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_int
+// CHECK: call i32 @llvm.[[TARGET]].firstbitshigh.i32
+uint test_firstbithigh_int(int p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_int2
+// CHECK: call <2 x i32> @llvm.[[TARGET]].firstbitshigh.v2i32
+uint2 test_firstbithigh_int2(int2 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_int3
+// CHECK: call <3 x i32> @llvm.[[TARGET]].firstbitshigh.v3i32
+uint3 test_firstbithigh_int3(int3 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_int4
+// CHECK: call <4 x i32> @llvm.[[TARGET]].firstbitshigh.v4i32
+uint4 test_firstbithigh_int4(int4 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_long
+// CHECK: call i32 @llvm.[[TARGET]].firstbitshigh.i64
+uint test_firstbithigh_long(int64_t p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_long2
+// CHECK: call <2 x i32> @llvm.[[TARGET]].firstbitshigh.v2i64
+uint2 test_firstbithigh_long2(int64_t2 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_long3
+// CHECK: call <3 x i32> @llvm.[[TARGET]].firstbitshigh.v3i64
+uint3 test_firstbithigh_long3(int64_t3 p0) {
+  return firstbithigh(p0);
+}
+
+// CHECK-LABEL: test_firstbithigh_long4
+// CHECK: call <4 x i32> @llvm.[[TARGET]].firstbitshigh.v4i64
+uint4 test_firstbithigh_long4(int64_t4 p0) {
+  return firstbithigh(p0);
+}

diff  --git a/clang/test/SemaHLSL/BuiltIns/firstbithigh-errors.hlsl b/clang/test/SemaHLSL/BuiltIns/firstbithigh-errors.hlsl
new file mode 100644
index 00000000000000..1912ab3ae806b3
--- /dev/null
+++ b/clang/test/SemaHLSL/BuiltIns/firstbithigh-errors.hlsl
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -emit-llvm-only -disable-llvm-passes -verify -verify-ignore-unexpected
+
+int test_too_few_arg() {
+  return firstbithigh();
+  // expected-error at -1 {{no matching function for call to 'firstbithigh'}}
+}
+
+int test_too_many_arg(int p0) {
+  return firstbithigh(p0, p0);
+  // expected-error at -1 {{no matching function for call to 'firstbithigh'}}
+}
+
+double test_int_builtin(double p0) {
+  return firstbithigh(p0);
+  // expected-error at -1 {{call to 'firstbithigh' is ambiguous}}
+}
+
+double2 test_int_builtin_2(double2 p0) {
+  return __builtin_hlsl_elementwise_firstbithigh(p0);
+  // expected-error at -1 {{1st argument must be a vector of integers
+  // (was 'double2' (aka 'vector<double, 2>'))}}
+}
+
+float test_int_builtin_3(float p0) {
+  return __builtin_hlsl_elementwise_firstbithigh(p0);
+  // expected-error at -1 {{1st argument must be a vector of integers
+  // (was 'float')}}
+}

diff  --git a/llvm/include/llvm/IR/IntrinsicsDirectX.td b/llvm/include/llvm/IR/IntrinsicsDirectX.td
index 8cd5ff9006c1b7..c3a935c39ddc30 100644
--- a/llvm/include/llvm/IR/IntrinsicsDirectX.td
+++ b/llvm/include/llvm/IR/IntrinsicsDirectX.td
@@ -93,4 +93,6 @@ def int_dx_step : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty, L
 def int_dx_splitdouble : DefaultAttrsIntrinsic<[llvm_anyint_ty, LLVMMatchType<0>], 
     [LLVMScalarOrSameVectorWidth<0, llvm_double_ty>], [IntrNoMem]>;
 def int_dx_radians : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>], [IntrNoMem]>;
+def int_dx_firstbituhigh : DefaultAttrsIntrinsic<[LLVMScalarOrSameVectorWidth<0, llvm_i32_ty>], [llvm_anyint_ty], [IntrNoMem]>;
+def int_dx_firstbitshigh : DefaultAttrsIntrinsic<[LLVMScalarOrSameVectorWidth<0, llvm_i32_ty>], [llvm_anyint_ty], [IntrNoMem]>;
 }

diff  --git a/llvm/include/llvm/IR/IntrinsicsSPIRV.td b/llvm/include/llvm/IR/IntrinsicsSPIRV.td
index 72fee94908db72..629d6759dd65fd 100644
--- a/llvm/include/llvm/IR/IntrinsicsSPIRV.td
+++ b/llvm/include/llvm/IR/IntrinsicsSPIRV.td
@@ -99,4 +99,6 @@ let TargetPrefix = "spv" in {
             [llvm_any_ty],
             [llvm_i32_ty, llvm_i32_ty, llvm_i32_ty, llvm_i32_ty, llvm_i1_ty],
             [IntrNoMem]>;
+  def int_spv_firstbituhigh : DefaultAttrsIntrinsic<[LLVMScalarOrSameVectorWidth<0, llvm_i32_ty>], [llvm_anyint_ty], [IntrNoMem]>;
+  def int_spv_firstbitshigh : DefaultAttrsIntrinsic<[LLVMScalarOrSameVectorWidth<0, llvm_i32_ty>], [llvm_anyint_ty], [IntrNoMem]>;
 }

diff  --git a/llvm/lib/Target/DirectX/DXIL.td b/llvm/lib/Target/DirectX/DXIL.td
index aa372b4e31f4b9..aab94e95a40ff9 100644
--- a/llvm/lib/Target/DirectX/DXIL.td
+++ b/llvm/lib/Target/DirectX/DXIL.td
@@ -564,6 +564,30 @@ def CountBits :  DXILOp<31, unaryBits> {
   let attributes = [Attributes<DXIL1_0, [ReadNone]>];
 }
 
+def FirstbitHi :  DXILOp<33, unaryBits> {
+  let Doc = "Returns the location of the first set bit starting from "
+            "the highest order bit and working downward.";
+  let LLVMIntrinsic = int_dx_firstbituhigh;
+  let arguments = [OverloadTy];
+  let result = Int32Ty;
+  let overloads =
+      [Overloads<DXIL1_0, [Int16Ty, Int32Ty, Int64Ty]>];
+  let stages = [Stages<DXIL1_0, [all_stages]>];
+  let attributes = [Attributes<DXIL1_0, [ReadNone]>];
+}
+
+def FirstbitSHi :  DXILOp<34, unaryBits> {
+  let Doc = "Returns the location of the first set bit from "
+            "the highest order bit based on the sign.";
+  let LLVMIntrinsic = int_dx_firstbitshigh;
+  let arguments = [OverloadTy];
+  let result = Int32Ty;
+  let overloads =
+      [Overloads<DXIL1_0, [Int16Ty, Int32Ty, Int64Ty]>];
+  let stages = [Stages<DXIL1_0, [all_stages]>];
+  let attributes = [Attributes<DXIL1_0, [ReadNone]>];
+}
+
 def FMax :  DXILOp<35, binary> {
   let Doc = "Float maximum. FMax(a,b) = a > b ? a : b";
   let LLVMIntrinsic = int_maxnum;

diff  --git a/llvm/lib/Target/DirectX/DirectXTargetTransformInfo.cpp b/llvm/lib/Target/DirectX/DirectXTargetTransformInfo.cpp
index 231afd8ae3eeaf..b0436a39423405 100644
--- a/llvm/lib/Target/DirectX/DirectXTargetTransformInfo.cpp
+++ b/llvm/lib/Target/DirectX/DirectXTargetTransformInfo.cpp
@@ -32,6 +32,8 @@ bool DirectXTTIImpl::isTargetIntrinsicTriviallyScalarizable(
   case Intrinsic::dx_rsqrt:
   case Intrinsic::dx_wave_readlane:
   case Intrinsic::dx_splitdouble:
+  case Intrinsic::dx_firstbituhigh:
+  case Intrinsic::dx_firstbitshigh:
     return true;
   default:
     return false;

diff  --git a/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp b/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
index af0df4d6e5d563..f66506beaa6ed6 100644
--- a/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
@@ -424,7 +424,7 @@ Register SPIRVGlobalRegistry::getOrCreateCompositeOrNull(
     LLT LLTy = LLT::scalar(64);
     Register SpvVecConst =
         CurMF->getRegInfo().createGenericVirtualRegister(LLTy);
-    CurMF->getRegInfo().setRegClass(SpvVecConst, &SPIRV::iIDRegClass);
+    CurMF->getRegInfo().setRegClass(SpvVecConst, getRegClass(SpvType));
     assignSPIRVTypeToVReg(SpvType, SpvVecConst, *CurMF);
     DT.add(CA, CurMF, SpvVecConst);
     MachineInstrBuilder MIB;

diff  --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 7aa5f4f2b1a8f1..be38b22f70c583 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -92,9 +92,26 @@ class SPIRVInstructionSelector : public InstructionSelector {
   bool spvSelect(Register ResVReg, const SPIRVType *ResType,
                  MachineInstr &I) const;
 
+  bool selectFirstBitHigh(Register ResVReg, const SPIRVType *ResType,
+                          MachineInstr &I, bool IsSigned) const;
+
+  bool selectFirstBitHigh16(Register ResVReg, const SPIRVType *ResType,
+                            MachineInstr &I, bool IsSigned) const;
+
+  bool selectFirstBitHigh32(Register ResVReg, const SPIRVType *ResType,
+                            MachineInstr &I, Register SrcReg,
+                            bool IsSigned) const;
+
+  bool selectFirstBitHigh64(Register ResVReg, const SPIRVType *ResType,
+                            MachineInstr &I, bool IsSigned) const;
+
   bool selectGlobalValue(Register ResVReg, MachineInstr &I,
                          const MachineInstr *Init = nullptr) const;
 
+  bool selectNAryOpWithSrcs(Register ResVReg, const SPIRVType *ResType,
+                            MachineInstr &I, std::vector<Register> SrcRegs,
+                            unsigned Opcode) const;
+
   bool selectUnOpWithSrc(Register ResVReg, const SPIRVType *ResType,
                          MachineInstr &I, Register SrcReg,
                          unsigned Opcode) const;
@@ -220,6 +237,8 @@ class SPIRVInstructionSelector : public InstructionSelector {
   bool selectPhi(Register ResVReg, const SPIRVType *ResType,
                  MachineInstr &I) const;
 
+  bool selectExtInst(Register ResVReg, const SPIRVType *RestType,
+                     MachineInstr &I, GL::GLSLExtInst GLInst) const;
   bool selectExtInst(Register ResVReg, const SPIRVType *ResType,
                      MachineInstr &I, CL::OpenCLExtInst CLInst) const;
   bool selectExtInst(Register ResVReg, const SPIRVType *ResType,
@@ -769,6 +788,14 @@ bool SPIRVInstructionSelector::spvSelect(Register ResVReg,
   }
 }
 
+bool SPIRVInstructionSelector::selectExtInst(Register ResVReg,
+                                             const SPIRVType *ResType,
+                                             MachineInstr &I,
+                                             GL::GLSLExtInst GLInst) const {
+  return selectExtInst(ResVReg, ResType, I,
+                       {{SPIRV::InstructionSet::GLSL_std_450, GLInst}});
+}
+
 bool SPIRVInstructionSelector::selectExtInst(Register ResVReg,
                                              const SPIRVType *ResType,
                                              MachineInstr &I,
@@ -816,6 +843,20 @@ bool SPIRVInstructionSelector::selectExtInst(Register ResVReg,
   return false;
 }
 
+bool SPIRVInstructionSelector::selectNAryOpWithSrcs(Register ResVReg,
+                                                    const SPIRVType *ResType,
+                                                    MachineInstr &I,
+                                                    std::vector<Register> Srcs,
+                                                    unsigned Opcode) const {
+  auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(Opcode))
+                 .addDef(ResVReg)
+                 .addUse(GR.getSPIRVTypeID(ResType));
+  for (Register SReg : Srcs) {
+    MIB.addUse(SReg);
+  }
+  return MIB.constrainAllUses(TII, TRI, RBI);
+}
+
 bool SPIRVInstructionSelector::selectUnOpWithSrc(Register ResVReg,
                                                  const SPIRVType *ResType,
                                                  MachineInstr &I,
@@ -2666,6 +2707,10 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
     return selectExtInst(ResVReg, ResType, I, CL::rsqrt, GL::InverseSqrt);
   case Intrinsic::spv_sign:
     return selectSign(ResVReg, ResType, I);
+  case Intrinsic::spv_firstbituhigh: // There is no CL equivalent of FindUMsb
+    return selectFirstBitHigh(ResVReg, ResType, I, /*IsSigned=*/false);
+  case Intrinsic::spv_firstbitshigh: // There is no CL equivalent of FindSMsb
+    return selectFirstBitHigh(ResVReg, ResType, I, /*IsSigned=*/true);
   case Intrinsic::spv_group_memory_barrier_with_group_sync: {
     Register MemSemReg =
         buildI32Constant(SPIRV::MemorySemantics::SequentiallyConsistent, I);
@@ -2786,6 +2831,160 @@ Register SPIRVInstructionSelector::buildPointerToResource(
   return AcReg;
 }
 
+bool SPIRVInstructionSelector::selectFirstBitHigh16(Register ResVReg,
+                                                    const SPIRVType *ResType,
+                                                    MachineInstr &I,
+                                                    bool IsSigned) const {
+  unsigned Opcode = IsSigned ? SPIRV::OpSConvert : SPIRV::OpUConvert;
+  // zero or sign extend
+  Register ExtReg = MRI->createVirtualRegister(GR.getRegClass(ResType));
+  bool Result =
+      selectUnOpWithSrc(ExtReg, ResType, I, I.getOperand(2).getReg(), Opcode);
+  return Result && selectFirstBitHigh32(ResVReg, ResType, I, ExtReg, IsSigned);
+}
+
+bool SPIRVInstructionSelector::selectFirstBitHigh32(Register ResVReg,
+                                                    const SPIRVType *ResType,
+                                                    MachineInstr &I,
+                                                    Register SrcReg,
+                                                    bool IsSigned) const {
+  unsigned Opcode = IsSigned ? GL::FindSMsb : GL::FindUMsb;
+  return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpExtInst))
+      .addDef(ResVReg)
+      .addUse(GR.getSPIRVTypeID(ResType))
+      .addImm(static_cast<uint32_t>(SPIRV::InstructionSet::GLSL_std_450))
+      .addImm(Opcode)
+      .addUse(SrcReg)
+      .constrainAllUses(TII, TRI, RBI);
+}
+
+bool SPIRVInstructionSelector::selectFirstBitHigh64(Register ResVReg,
+                                                    const SPIRVType *ResType,
+                                                    MachineInstr &I,
+                                                    bool IsSigned) const {
+  Register OpReg = I.getOperand(2).getReg();
+  // 1. split our int64 into 2 pieces using a bitcast
+  unsigned count = GR.getScalarOrVectorComponentCount(ResType);
+  SPIRVType *baseType = GR.retrieveScalarOrVectorIntType(ResType);
+  MachineIRBuilder MIRBuilder(I);
+  SPIRVType *postCastT =
+      GR.getOrCreateSPIRVVectorType(baseType, 2 * count, MIRBuilder);
+  Register bitcastReg = MRI->createVirtualRegister(GR.getRegClass(postCastT));
+  bool Result =
+      selectUnOpWithSrc(bitcastReg, postCastT, I, OpReg, SPIRV::OpBitcast);
+
+  // 2. call firstbithigh
+  Register FBHReg = MRI->createVirtualRegister(GR.getRegClass(postCastT));
+  Result &= selectFirstBitHigh32(FBHReg, postCastT, I, bitcastReg, IsSigned);
+
+  // 3. split result vector into high bits and low bits
+  Register HighReg = MRI->createVirtualRegister(GR.getRegClass(ResType));
+  Register LowReg = MRI->createVirtualRegister(GR.getRegClass(ResType));
+
+  bool ZeroAsNull = STI.isOpenCLEnv();
+  bool isScalarRes = ResType->getOpcode() != SPIRV::OpTypeVector;
+  if (isScalarRes) {
+    // if scalar do a vector extract
+    Result &= selectNAryOpWithSrcs(
+        HighReg, ResType, I,
+        {FBHReg, GR.getOrCreateConstInt(0, I, ResType, TII, ZeroAsNull)},
+        SPIRV::OpVectorExtractDynamic);
+    Result &= selectNAryOpWithSrcs(
+        LowReg, ResType, I,
+        {FBHReg, GR.getOrCreateConstInt(1, I, ResType, TII, ZeroAsNull)},
+        SPIRV::OpVectorExtractDynamic);
+  } else { // vector case do a shufflevector
+    auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(),
+                       TII.get(SPIRV::OpVectorShuffle))
+                   .addDef(HighReg)
+                   .addUse(GR.getSPIRVTypeID(ResType))
+                   .addUse(FBHReg)
+                   .addUse(FBHReg);
+    // ^^ this vector will not be selected from; could be empty
+    unsigned j;
+    for (j = 0; j < count * 2; j += 2) {
+      MIB.addImm(j);
+    }
+    Result &= MIB.constrainAllUses(TII, TRI, RBI);
+
+    // get low bits
+    MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(),
+                  TII.get(SPIRV::OpVectorShuffle))
+              .addDef(LowReg)
+              .addUse(GR.getSPIRVTypeID(ResType))
+              .addUse(FBHReg)
+              .addUse(FBHReg);
+    // ^^ this vector will not be selected from; could be empty
+    for (j = 1; j < count * 2; j += 2) {
+      MIB.addImm(j);
+    }
+    Result &= MIB.constrainAllUses(TII, TRI, RBI);
+  }
+
+  // 4. check if result of each top 32 bits is == -1
+  SPIRVType *BoolType = GR.getOrCreateSPIRVBoolType(I, TII);
+  Register NegOneReg;
+  Register Reg0;
+  Register Reg32;
+  unsigned selectOp;
+  unsigned addOp;
+  if (isScalarRes) {
+    NegOneReg =
+        GR.getOrCreateConstInt((unsigned)-1, I, ResType, TII, ZeroAsNull);
+    Reg0 = GR.getOrCreateConstInt(0, I, ResType, TII, ZeroAsNull);
+    Reg32 = GR.getOrCreateConstInt(32, I, ResType, TII, ZeroAsNull);
+    selectOp = SPIRV::OpSelectSISCond;
+    addOp = SPIRV::OpIAddS;
+  } else {
+    BoolType = GR.getOrCreateSPIRVVectorType(BoolType, count, MIRBuilder);
+    NegOneReg =
+        GR.getOrCreateConstVector((unsigned)-1, I, ResType, TII, ZeroAsNull);
+    Reg0 = GR.getOrCreateConstVector(0, I, ResType, TII, ZeroAsNull);
+    Reg32 = GR.getOrCreateConstVector(32, I, ResType, TII, ZeroAsNull);
+    selectOp = SPIRV::OpSelectVIVCond;
+    addOp = SPIRV::OpIAddV;
+  }
+
+  // check if the high bits are == -1; true if -1
+  Register BReg = MRI->createVirtualRegister(GR.getRegClass(BoolType));
+  Result &= selectNAryOpWithSrcs(BReg, BoolType, I, {HighReg, NegOneReg},
+                                 SPIRV::OpIEqual);
+
+  // Select low bits if true in BReg, otherwise high bits
+  Register TmpReg = MRI->createVirtualRegister(GR.getRegClass(ResType));
+  Result &= selectNAryOpWithSrcs(TmpReg, ResType, I, {BReg, LowReg, HighReg},
+                                 selectOp);
+
+  // Add 32 for high bits, 0 for low bits
+  Register ValReg = MRI->createVirtualRegister(GR.getRegClass(ResType));
+  Result &=
+      selectNAryOpWithSrcs(ValReg, ResType, I, {BReg, Reg0, Reg32}, selectOp);
+
+  return Result &&
+         selectNAryOpWithSrcs(ResVReg, ResType, I, {ValReg, TmpReg}, addOp);
+}
+
+bool SPIRVInstructionSelector::selectFirstBitHigh(Register ResVReg,
+                                                  const SPIRVType *ResType,
+                                                  MachineInstr &I,
+                                                  bool IsSigned) const {
+  // FindUMsb and FindSMsb intrinsics only support 32 bit integers
+  Register OpReg = I.getOperand(2).getReg();
+  SPIRVType *OpType = GR.getSPIRVTypeForVReg(OpReg);
+
+  switch (GR.getScalarOrVectorBitWidth(OpType)) {
+  case 16:
+    return selectFirstBitHigh16(ResVReg, ResType, I, IsSigned);
+  case 32:
+    return selectFirstBitHigh32(ResVReg, ResType, I, OpReg, IsSigned);
+  case 64:
+    return selectFirstBitHigh64(ResVReg, ResType, I, IsSigned);
+  default:
+    report_fatal_error(
+        "spv_firstbituhigh and spv_firstbitshigh only support 16,32,64 bits.");
+  }
+}
+
 bool SPIRVInstructionSelector::selectAllocaArray(Register ResVReg,
                                                  const SPIRVType *ResType,
                                                  MachineInstr &I) const {

diff  --git a/llvm/test/CodeGen/DirectX/firstbithigh.ll b/llvm/test/CodeGen/DirectX/firstbithigh.ll
new file mode 100644
index 00000000000000..5584c433fb6f0e
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/firstbithigh.ll
@@ -0,0 +1,91 @@
+; RUN: opt -S -scalarizer -dxil-op-lower -mtriple=dxil-pc-shadermodel6.3-library %s | FileCheck %s
+
+; Make sure dxil operation function calls for firstbithigh are generated for all integer types.
+
+define noundef i32 @test_firstbithigh_ushort(i16 noundef %a) {
+entry:
+; CHECK: call i32 @dx.op.unaryBits.i16(i32 33, i16 %{{.*}})
+  %elt.firstbithigh = call i32 @llvm.dx.firstbituhigh.i16(i16 %a)
+  ret i32 %elt.firstbithigh
+}
+
+define noundef i32 @test_firstbithigh_short(i16 noundef %a) {
+entry:
+; CHECK: call i32 @dx.op.unaryBits.i16(i32 34, i16 %{{.*}})
+  %elt.firstbithigh = call i32 @llvm.dx.firstbitshigh.i16(i16 %a)
+  ret i32 %elt.firstbithigh
+}
+
+define noundef i32 @test_firstbithigh_uint(i32 noundef %a) {
+entry:
+; CHECK: call i32 @dx.op.unaryBits.i32(i32 33, i32 %{{.*}})
+  %elt.firstbithigh = call i32 @llvm.dx.firstbituhigh.i32(i32 %a)
+  ret i32 %elt.firstbithigh
+}
+
+define noundef i32 @test_firstbithigh_int(i32 noundef %a) {
+entry:
+; CHECK: call i32 @dx.op.unaryBits.i32(i32 34, i32 %{{.*}})
+  %elt.firstbithigh = call i32 @llvm.dx.firstbitshigh.i32(i32 %a)
+  ret i32 %elt.firstbithigh
+}
+
+define noundef i32 @test_firstbithigh_ulong(i64 noundef %a) {
+entry:
+; CHECK: call i32 @dx.op.unaryBits.i64(i32 33, i64 %{{.*}})
+  %elt.firstbithigh = call i32 @llvm.dx.firstbituhigh.i64(i64 %a)
+  ret i32 %elt.firstbithigh
+}
+
+define noundef i32 @test_firstbithigh_long(i64 noundef %a) {
+entry:
+; CHECK: call i32 @dx.op.unaryBits.i64(i32 34, i64 %{{.*}})
+  %elt.firstbithigh = call i32 @llvm.dx.firstbitshigh.i64(i64 %a)
+  ret i32 %elt.firstbithigh
+}
+
+define noundef <4 x i32> @test_firstbituhigh_vec4_i32(<4 x i32> noundef %a)  {
+entry:
+  ; CHECK: [[ee0:%.*]] = extractelement <4 x i32> %a, i64 0
+  ; CHECK: [[ie0:%.*]] = call i32 @dx.op.unaryBits.i32(i32 33, i32 [[ee0]])
+  ; CHECK: [[ee1:%.*]] = extractelement <4 x i32> %a, i64 1
+  ; CHECK: [[ie1:%.*]] = call i32 @dx.op.unaryBits.i32(i32 33, i32 [[ee1]])
+  ; CHECK: [[ee2:%.*]] = extractelement <4 x i32> %a, i64 2
+  ; CHECK: [[ie2:%.*]] = call i32 @dx.op.unaryBits.i32(i32 33, i32 [[ee2]])
+  ; CHECK: [[ee3:%.*]] = extractelement <4 x i32> %a, i64 3
+  ; CHECK: [[ie3:%.*]] = call i32 @dx.op.unaryBits.i32(i32 33, i32 [[ee3]])
+  ; CHECK: insertelement <4 x i32> poison, i32 [[ie0]], i64 0
+  ; CHECK: insertelement <4 x i32> %{{.*}}, i32 [[ie1]], i64 1
+  ; CHECK: insertelement <4 x i32> %{{.*}}, i32 [[ie2]], i64 2
+  ; CHECK: insertelement <4 x i32> %{{.*}}, i32 [[ie3]], i64 3
+  %2 = call <4 x i32> @llvm.dx.firstbituhigh.v4i32(<4 x i32> %a)
+  ret <4 x i32> %2
+}
+
+define noundef <4 x i32> @test_firstbitshigh_vec4_i32(<4 x i32> noundef %a)  {
+entry:
+  ; CHECK: [[ee0:%.*]] = extractelement <4 x i32> %a, i64 0
+  ; CHECK: [[ie0:%.*]] = call i32 @dx.op.unaryBits.i32(i32 34, i32 [[ee0]])
+  ; CHECK: [[ee1:%.*]] = extractelement <4 x i32> %a, i64 1
+  ; CHECK: [[ie1:%.*]] = call i32 @dx.op.unaryBits.i32(i32 34, i32 [[ee1]])
+  ; CHECK: [[ee2:%.*]] = extractelement <4 x i32> %a, i64 2
+  ; CHECK: [[ie2:%.*]] = call i32 @dx.op.unaryBits.i32(i32 34, i32 [[ee2]])
+  ; CHECK: [[ee3:%.*]] = extractelement <4 x i32> %a, i64 3
+  ; CHECK: [[ie3:%.*]] = call i32 @dx.op.unaryBits.i32(i32 34, i32 [[ee3]])
+  ; CHECK: insertelement <4 x i32> poison, i32 [[ie0]], i64 0
+  ; CHECK: insertelement <4 x i32> %{{.*}}, i32 [[ie1]], i64 1
+  ; CHECK: insertelement <4 x i32> %{{.*}}, i32 [[ie2]], i64 2
+  ; CHECK: insertelement <4 x i32> %{{.*}}, i32 [[ie3]], i64 3
+  %2 = call <4 x i32> @llvm.dx.firstbitshigh.v4i32(<4 x i32> %a)
+  ret <4 x i32> %2
+}
+
+declare i32 @llvm.dx.firstbituhigh.i16(i16)
+declare i32 @llvm.dx.firstbituhigh.i32(i32)
+declare i32 @llvm.dx.firstbituhigh.i64(i64)
+declare <4 x i32> @llvm.dx.firstbituhigh.v4i32(<4 x i32>)
+
+declare i32 @llvm.dx.firstbitshigh.i16(i16)
+declare i32 @llvm.dx.firstbitshigh.i32(i32)
+declare i32 @llvm.dx.firstbitshigh.i64(i64)
+declare <4 x i32> @llvm.dx.firstbitshigh.v4i32(<4 x i32>)

diff  --git a/llvm/test/CodeGen/DirectX/firstbitshigh_error.ll b/llvm/test/CodeGen/DirectX/firstbitshigh_error.ll
new file mode 100644
index 00000000000000..22982a03e47921
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/firstbitshigh_error.ll
@@ -0,0 +1,10 @@
+; RUN: not opt -S -dxil-op-lower -mtriple=dxil-pc-shadermodel6.3-library %s 2>&1 | FileCheck %s
+
+; DXIL operation firstbitshigh does not support double overload type
+; CHECK: invalid intrinsic signature
+
+define noundef double @firstbitshigh_double(double noundef %a) {
+entry:
+  %1 = call double @llvm.dx.firstbitshigh.f64(double %a)
+  ret double %1
+}

diff  --git a/llvm/test/CodeGen/DirectX/firstbituhigh_error.ll b/llvm/test/CodeGen/DirectX/firstbituhigh_error.ll
new file mode 100644
index 00000000000000..b611a96ffc2f9c
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/firstbituhigh_error.ll
@@ -0,0 +1,10 @@
+; RUN: not opt -S -dxil-op-lower -mtriple=dxil-pc-shadermodel6.3-library %s 2>&1 | FileCheck %s
+
+; DXIL operation firstbituhigh does not support double overload type
+; CHECK: invalid intrinsic signature
+
+define noundef double @firstbituhigh_double(double noundef %a) {
+entry:
+  %1 = call double @llvm.dx.firstbituhigh.f64(double %a)
+  ret double %1
+}

diff  --git a/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/firstbithigh.ll b/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/firstbithigh.ll
new file mode 100644
index 00000000000000..3d35e102310f50
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/firstbithigh.ll
@@ -0,0 +1,107 @@
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; CHECK: OpMemoryModel Logical GLSL450
+; CHECK-DAG: [[Z:%.*]] = OpConstant %[[#]] 0
+; CHECK-DAG: [[X:%.*]] = OpConstant %[[#]] 1
+
+define noundef i32 @firstbituhigh_i32(i32 noundef %a) {
+entry:
+; CHECK: %[[#]] = OpExtInst %[[#]] %[[#]] FindUMsb %[[#]]
+  %elt.firstbituhigh = call i32 @llvm.spv.firstbituhigh.i32(i32 %a)
+  ret i32 %elt.firstbituhigh
+}
+
+define noundef <2 x i32> @firstbituhigh_2xi32(<2 x i32> noundef %a) {
+entry:
+; CHECK: %[[#]] = OpExtInst %[[#]] %[[#]] FindUMsb %[[#]]
+  %elt.firstbituhigh = call <2 x i32> @llvm.spv.firstbituhigh.v2i32(<2 x i32> %a)
+  ret <2 x i32> %elt.firstbituhigh
+}
+
+define noundef i32 @firstbituhigh_i16(i16 noundef %a) {
+entry:
+; CHECK: [[A:%.*]] = OpUConvert %[[#]]
+; CHECK: %[[#]] = OpExtInst %[[#]] %[[#]] FindUMsb [[A]]
+  %elt.firstbituhigh = call i32 @llvm.spv.firstbituhigh.i16(i16 %a)
+  ret i32 %elt.firstbituhigh
+}
+
+define noundef <2 x i32> @firstbituhigh_v2i16(<2 x i16> noundef %a) {
+entry:
+; CHECK: [[A:%.*]] = OpUConvert %[[#]]
+; CHECK: %[[#]] = OpExtInst %[[#]] %[[#]] FindUMsb [[A]]
+  %elt.firstbituhigh = call <2 x i32> @llvm.spv.firstbituhigh.v2i16(<2 x i16> %a)
+  ret <2 x i32> %elt.firstbituhigh
+}
+
+define noundef i32 @firstbituhigh_i64(i64 noundef %a) {
+entry:
+; CHECK: [[O:%.*]] = OpBitcast %[[#]] %[[#]]
+; CHECK: [[N:%.*]] = OpExtInst %[[#]] %[[#]] FindUMsb [[O]]
+; CHECK: [[M:%.*]] = OpVectorExtractDynamic %[[#]] [[N]] [[Z]]
+; CHECK: [[L:%.*]] = OpVectorExtractDynamic %[[#]] [[N]] [[X]]
+; CHECK: [[I:%.*]] = OpIEqual %[[#]] [[M]] %[[#]]
+; CHECK: [[H:%.*]] = OpSelect %[[#]] [[I]] [[L]] [[M]]
+; CHECK: [[C:%.*]] = OpSelect %[[#]] [[I]] %[[#]] %[[#]]
+; CHECK: [[B:%.*]] = OpIAdd %[[#]] [[C]] [[H]]
+  %elt.firstbituhigh = call i32 @llvm.spv.firstbituhigh.i64(i64 %a)
+  ret i32 %elt.firstbituhigh
+}
+
+define noundef <2 x i32> @firstbituhigh_v2i64(<2 x i64> noundef %a) {
+entry:
+; CHECK: [[O:%.*]] = OpBitcast %[[#]] %[[#]]
+; CHECK: [[N:%.*]] = OpExtInst %[[#]] %[[#]] FindUMsb [[O]]
+; CHECK: [[M:%.*]] = OpVectorShuffle %[[#]] [[N]] [[N]] 0
+; CHECK: [[L:%.*]] = OpVectorShuffle %[[#]] [[N]] [[N]] 1
+; CHECK: [[I:%.*]] = OpIEqual %[[#]] [[M]] %[[#]]
+; CHECK: [[H:%.*]] = OpSelect %[[#]] [[I]] [[L]] [[M]]
+; CHECK: [[C:%.*]] = OpSelect %[[#]] [[I]] %[[#]] %[[#]]
+; CHECK: [[B:%.*]] = OpIAdd %[[#]] [[C]] [[H]]
+; CHECK: OpReturnValue [[B]]
+  %elt.firstbituhigh = call <2 x i32> @llvm.spv.firstbituhigh.v2i64(<2 x i64> %a)
+  ret <2 x i32> %elt.firstbituhigh
+}
+
+define noundef i32 @firstbitshigh_i32(i32 noundef %a) {
+entry:
+; CHECK: %[[#]] = OpExtInst %[[#]] %[[#]] FindSMsb %[[#]]
+  %elt.firstbitshigh = call i32 @llvm.spv.firstbitshigh.i32(i32 %a)
+  ret i32 %elt.firstbitshigh
+}
+
+define noundef i32 @firstbitshigh_i16(i16 noundef %a) {
+entry:
+; CHECK: [[A:%.*]] = OpSConvert %[[#]]
+; CHECK: %[[#]] = OpExtInst %[[#]] %[[#]] FindSMsb %[[#]]
+  %elt.firstbitshigh = call i32 @llvm.spv.firstbitshigh.i16(i16 %a)
+  ret i32 %elt.firstbitshigh
+}
+
+define noundef i32 @firstbitshigh_i64(i64 noundef %a) {
+entry:
+; CHECK: [[O:%.*]] = OpBitcast %[[#]] %[[#]]
+; CHECK: [[N:%.*]] = OpExtInst %[[#]] %[[#]] FindSMsb [[O]]
+; CHECK: [[M:%.*]] = OpVectorExtractDynamic %[[#]] [[N]] [[Z]]
+; CHECK: [[L:%.*]] = OpVectorExtractDynamic %[[#]] [[N]] [[X]]
+; CHECK: [[I:%.*]] = OpIEqual %[[#]] [[M]] %[[#]]
+; CHECK: [[H:%.*]] = OpSelect %[[#]] [[I]] [[L]] [[M]]
+; CHECK: [[C:%.*]] = OpSelect %[[#]] [[I]] %[[#]] %[[#]]
+; CHECK: [[B:%.*]] = OpIAdd %[[#]] [[C]] [[H]]
+  %elt.firstbitshigh = call i32 @llvm.spv.firstbitshigh.i64(i64 %a)
+  ret i32 %elt.firstbitshigh
+}
+
+;declare i16 @llvm.spv.firstbituhigh.i16(i16)
+;declare i32 @llvm.spv.firstbituhigh.i32(i32)
+;declare i64 @llvm.spv.firstbituhigh.i64(i64)
+;declare i16 @llvm.spv.firstbituhigh.v2i16(<2 x i16>)
+;declare i32 @llvm.spv.firstbituhigh.v2i32(<2 x i32>)
+;declare i64 @llvm.spv.firstbituhigh.v2i64(<2 x i64>)
+;declare i16 @llvm.spv.firstbitshigh.i16(i16)
+;declare i32 @llvm.spv.firstbitshigh.i32(i32)
+;declare i64 @llvm.spv.firstbitshigh.i64(i64)
+;declare i16 @llvm.spv.firstbitshigh.v2i16(<2 x i16>)
+;declare i32 @llvm.spv.firstbitshigh.v2i32(<2 x i32>)
+;declare i64 @llvm.spv.firstbitshigh.v2i64(<2 x i64>)


        


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