[SPIRV][HLSL] Add lowering of `rsqrt` to SPIRV (#95849)

Add lowering of `rsqrt` to SPIRV.

Fixes #88949

6 files changed, 164 insertions, 41 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 511e1fd..eb56bba 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -18331,8 +18331,8 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
     if (!E->getArg(0)->getType()->hasFloatingRepresentation())
       llvm_unreachable("rsqrt operand must have a float representation");
     return Builder.CreateIntrinsic(
-        /*ReturnType=*/Op0->getType(), Intrinsic::dx_rsqrt,
-        ArrayRef<Value *>{Op0}, nullptr, "dx.rsqrt");
+        /*ReturnType=*/Op0->getType(), CGM.getHLSLRuntime().getRsqrtIntrinsic(),
+        ArrayRef<Value *>{Op0}, nullptr, "hlsl.rsqrt");
   }
   case Builtin::BI__builtin_hlsl_wave_get_lane_index: {
     return EmitRuntimeCall(CGM.CreateRuntimeFunction(
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index 0abe39d..4036ce7 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -75,6 +75,7 @@ public:
   GENERATE_HLSL_INTRINSIC_FUNCTION(All, all)
   GENERATE_HLSL_INTRINSIC_FUNCTION(Any, any)
   GENERATE_HLSL_INTRINSIC_FUNCTION(Lerp, lerp)
+  GENERATE_HLSL_INTRINSIC_FUNCTION(Rsqrt, rsqrt)
   GENERATE_HLSL_INTRINSIC_FUNCTION(ThreadId, thread_id)
 
   //===----------------------------------------------------------------------===//
diff --git a/clang/test/CodeGenHLSL/builtins/rsqrt.hlsl b/clang/test/CodeGenHLSL/builtins/rsqrt.hlsl
index c87a8c4..bb96ad8 100644
--- a/clang/test/CodeGenHLSL/builtins/rsqrt.hlsl
+++ b/clang/test/CodeGenHLSL/builtins/rsqrt.hlsl
@@ -1,53 +1,84 @@
 // 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 \ 
-// RUN:   --check-prefixes=CHECK,NATIVE_HALF
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s \
+// RUN:   --check-prefixes=CHECK,DXIL_CHECK,DXIL_NATIVE_HALF,NATIVE_HALF
 // RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
 // RUN:   dxil-pc-shadermodel6.3-library %s -emit-llvm -disable-llvm-passes \
-// RUN:   -o - | FileCheck %s --check-prefixes=CHECK,NO_HALF
+// RUN:   -o - | FileCheck %s --check-prefixes=CHECK,DXIL_CHECK,NO_HALF,DXIL_NO_HALF
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   spirv-unknown-vulkan-compute %s -fnative-half-type \
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s \
+// RUN:   --check-prefixes=CHECK,SPIR_CHECK,NATIVE_HALF,SPIR_NATIVE_HALF
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   spirv-unknown-vulkan-compute %s -emit-llvm -disable-llvm-passes \
+// RUN:   -o - | FileCheck %s --check-prefixes=CHECK,SPIR_CHECK,NO_HALF,SPIR_NO_HALF
 
-// NATIVE_HALF: define noundef half @
-// NATIVE_HALF: %dx.rsqrt = call half @llvm.dx.rsqrt.f16(
-// NATIVE_HALF: ret half %dx.rsqrt
-// NO_HALF: define noundef float @"?test_rsqrt_half@@YA$halff@$halff@@Z"(
-// NO_HALF: %dx.rsqrt = call float @llvm.dx.rsqrt.f32(
-// NO_HALF: ret float %dx.rsqrt
+// DXIL_NATIVE_HALF: define noundef half @
+// SPIR_NATIVE_HALF: define spir_func noundef half @
+// DXIL_NATIVE_HALF: %hlsl.rsqrt = call half @llvm.dx.rsqrt.f16(
+// SPIR_NATIVE_HALF: %hlsl.rsqrt = call half @llvm.spv.rsqrt.f16(
+// NATIVE_HALF: ret half %hlsl.rsqrt
+// DXIL_NO_HALF: define noundef float @
+// SPIR_NO_HALF: define spir_func noundef float @
+// DXIL_NO_HALF: %hlsl.rsqrt = call float @llvm.dx.rsqrt.f32(
+// SPIR_NO_HALF: %hlsl.rsqrt = call float @llvm.spv.rsqrt.f32(
+// NO_HALF: ret float %hlsl.rsqrt
 half test_rsqrt_half(half p0) { return rsqrt(p0); }
-// NATIVE_HALF: define noundef <2 x half> @
-// NATIVE_HALF: %dx.rsqrt = call <2 x half> @llvm.dx.rsqrt.v2f16
-// NATIVE_HALF: ret <2 x half> %dx.rsqrt
-// NO_HALF: define noundef <2 x float> @
-// NO_HALF: %dx.rsqrt = call <2 x float> @llvm.dx.rsqrt.v2f32(
-// NO_HALF: ret <2 x float> %dx.rsqrt
+// DXIL_NATIVE_HALF: define noundef <2 x half> @
+// SPIR_NATIVE_HALF: define spir_func noundef <2 x half> @
+// DXIL_NATIVE_HALF: %hlsl.rsqrt = call <2 x half> @llvm.dx.rsqrt.v2f16
+// SPIR_NATIVE_HALF: %hlsl.rsqrt = call <2 x half> @llvm.spv.rsqrt.v2f16
+// NATIVE_HALF: ret <2 x half> %hlsl.rsqrt
+// DXIL_NO_HALF: define noundef <2 x float> @
+// SPIR_NO_HALF: define spir_func noundef <2 x float> @
+// DXIL_NO_HALF: %hlsl.rsqrt = call <2 x float> @llvm.dx.rsqrt.v2f32(
+// SPIR_NO_HALF: %hlsl.rsqrt = call <2 x float> @llvm.spv.rsqrt.v2f32(
+// NO_HALF: ret <2 x float> %hlsl.rsqrt
 half2 test_rsqrt_half2(half2 p0) { return rsqrt(p0); }
-// NATIVE_HALF: define noundef <3 x half> @
-// NATIVE_HALF: %dx.rsqrt = call <3 x half> @llvm.dx.rsqrt.v3f16
-// NATIVE_HALF: ret <3 x half> %dx.rsqrt
-// NO_HALF: define noundef <3 x float> @
-// NO_HALF: %dx.rsqrt = call <3 x float> @llvm.dx.rsqrt.v3f32(
-// NO_HALF: ret <3 x float> %dx.rsqrt
+// DXIL_NATIVE_HALF: define noundef <3 x half> @
+// SPIR_NATIVE_HALF: define spir_func noundef <3 x half> @
+// DXIL_NATIVE_HALF: %hlsl.rsqrt = call <3 x half> @llvm.dx.rsqrt.v3f16
+// SPIR_NATIVE_HALF: %hlsl.rsqrt = call <3 x half> @llvm.spv.rsqrt.v3f16
+// NATIVE_HALF: ret <3 x half> %hlsl.rsqrt
+// DXIL_NO_HALF: define noundef <3 x float> @
+// SPIR_NO_HALF: define spir_func noundef <3 x float> @
+// DXIL_NO_HALF: %hlsl.rsqrt = call <3 x float> @llvm.dx.rsqrt.v3f32(
+// SPIR_NO_HALF: %hlsl.rsqrt = call <3 x float> @llvm.spv.rsqrt.v3f32(
+// NO_HALF: ret <3 x float> %hlsl.rsqrt
 half3 test_rsqrt_half3(half3 p0) { return rsqrt(p0); }
-// NATIVE_HALF: define noundef <4 x half> @
-// NATIVE_HALF: %dx.rsqrt = call <4 x half> @llvm.dx.rsqrt.v4f16
-// NATIVE_HALF: ret <4 x half> %dx.rsqrt
-// NO_HALF: define noundef <4 x float> @
-// NO_HALF: %dx.rsqrt = call <4 x float> @llvm.dx.rsqrt.v4f32(
-// NO_HALF: ret <4 x float> %dx.rsqrt
+// DXIL_NATIVE_HALF: define noundef <4 x half> @
+// SPIR_NATIVE_HALF: define spir_func noundef <4 x half> @
+// DXIL_NATIVE_HALF: %hlsl.rsqrt = call <4 x half> @llvm.dx.rsqrt.v4f16
+// SPIR_NATIVE_HALF: %hlsl.rsqrt = call <4 x half> @llvm.spv.rsqrt.v4f16
+// NATIVE_HALF: ret <4 x half> %hlsl.rsqrt
+// DXIL_NO_HALF: define noundef <4 x float> @
+// SPIR_NO_HALF: define spir_func noundef <4 x float> @
+// DXIL_NO_HALF: %hlsl.rsqrt = call <4 x float> @llvm.dx.rsqrt.v4f32(
+// SPIR_NO_HALF: %hlsl.rsqrt = call <4 x float> @llvm.spv.rsqrt.v4f32(
+// NO_HALF: ret <4 x float> %hlsl.rsqrt
 half4 test_rsqrt_half4(half4 p0) { return rsqrt(p0); }
 
-// CHECK: define noundef float @
-// CHECK: %dx.rsqrt = call float @llvm.dx.rsqrt.f32(
-// CHECK: ret float %dx.rsqrt
+// DXIL_CHECK: define noundef float @
+// SPIR_CHECK: define spir_func noundef float @
+// DXIL_CHECK: %hlsl.rsqrt = call float @llvm.dx.rsqrt.f32(
+// SPIR_CHECK: %hlsl.rsqrt = call float @llvm.spv.rsqrt.f32(
+// CHECK: ret float %hlsl.rsqrt
 float test_rsqrt_float(float p0) { return rsqrt(p0); }
-// CHECK: define noundef <2 x float> @
-// CHECK: %dx.rsqrt = call <2 x float> @llvm.dx.rsqrt.v2f32
-// CHECK: ret <2 x float> %dx.rsqrt
+// DXIL_CHECK: define noundef <2 x float> @
+// SPIR_CHECK: define spir_func noundef <2 x float> @
+// DXIL_CHECK: %hlsl.rsqrt = call <2 x float> @llvm.dx.rsqrt.v2f32
+// SPIR_CHECK: %hlsl.rsqrt = call <2 x float> @llvm.spv.rsqrt.v2f32
+// CHECK: ret <2 x float> %hlsl.rsqrt
 float2 test_rsqrt_float2(float2 p0) { return rsqrt(p0); }
-// CHECK: define noundef <3 x float> @
-// CHECK: %dx.rsqrt = call <3 x float> @llvm.dx.rsqrt.v3f32
-// CHECK: ret <3 x float> %dx.rsqrt
+// DXIL_CHECK: define noundef <3 x float> @
+// SPIR_CHECK: define spir_func noundef <3 x float> @
+// DXIL_CHECK: %hlsl.rsqrt = call <3 x float> @llvm.dx.rsqrt.v3f32
+// SPIR_CHECK: %hlsl.rsqrt = call <3 x float> @llvm.spv.rsqrt.v3f32
+// CHECK: ret <3 x float> %hlsl.rsqrt
 float3 test_rsqrt_float3(float3 p0) { return rsqrt(p0); }
-// CHECK: define noundef <4 x float> @
-// CHECK: %dx.rsqrt = call <4 x float> @llvm.dx.rsqrt.v4f32
-// CHECK: ret <4 x float> %dx.rsqrt
+// DXIL_CHECK: define noundef <4 x float> @
+// SPIR_CHECK: define spir_func noundef <4 x float> @
+// DXIL_CHECK: %hlsl.rsqrt = call <4 x float> @llvm.dx.rsqrt.v4f32
+// SPIR_CHECK: %hlsl.rsqrt = call <4 x float> @llvm.spv.rsqrt.v4f32
+// CHECK: ret <4 x float> %hlsl.rsqrt
 float4 test_rsqrt_float4(float4 p0) { return rsqrt(p0); }
diff --git a/llvm/include/llvm/IR/IntrinsicsSPIRV.td b/llvm/include/llvm/IR/IntrinsicsSPIRV.td
index 90f1267..683acf4 100644
--- a/llvm/include/llvm/IR/IntrinsicsSPIRV.td
+++ b/llvm/include/llvm/IR/IntrinsicsSPIRV.td
@@ -62,4 +62,5 @@ let TargetPrefix = "spv" in {
   def int_spv_any : DefaultAttrsIntrinsic<[llvm_i1_ty], [llvm_any_ty]>;
   def int_spv_lerp : Intrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty, LLVMMatchType<0>,LLVMMatchType<0>], 
     [IntrNoMem, IntrWillReturn] >;
+  def int_spv_rsqrt : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty]>;
 }
diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index db83172..b9e5569 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -173,6 +173,9 @@ private:
   bool selectFmix(Register ResVReg, const SPIRVType *ResType,
                   MachineInstr &I) const;
 
+  bool selectRsqrt(Register ResVReg, const SPIRVType *ResType,
+                   MachineInstr &I) const;
+
   void renderImm32(MachineInstrBuilder &MIB, const MachineInstr &I,
                    int OpIdx) const;
   void renderFImm32(MachineInstrBuilder &MIB, const MachineInstr &I,
@@ -1315,6 +1318,23 @@ bool SPIRVInstructionSelector::selectFmix(Register ResVReg,
       .constrainAllUses(TII, TRI, RBI);
 }
 
+bool SPIRVInstructionSelector::selectRsqrt(Register ResVReg,
+                                           const SPIRVType *ResType,
+                                           MachineInstr &I) const {
+
+  assert(I.getNumOperands() == 3);
+  assert(I.getOperand(2).isReg());
+  MachineBasicBlock &BB = *I.getParent();
+
+  return BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpExtInst))
+      .addDef(ResVReg)
+      .addUse(GR.getSPIRVTypeID(ResType))
+      .addImm(static_cast<uint32_t>(SPIRV::InstructionSet::GLSL_std_450))
+      .addImm(GL::InverseSqrt)
+      .addUse(I.getOperand(2).getReg())
+      .constrainAllUses(TII, TRI, RBI);
+}
+
 bool SPIRVInstructionSelector::selectBitreverse(Register ResVReg,
                                                 const SPIRVType *ResType,
                                                 MachineInstr &I) const {
@@ -1992,6 +2012,8 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
     return selectAny(ResVReg, ResType, I);
   case Intrinsic::spv_lerp:
     return selectFmix(ResVReg, ResType, I);
+  case Intrinsic::spv_rsqrt:
+    return selectRsqrt(ResVReg, ResType, I);
   case Intrinsic::spv_lifetime_start:
   case Intrinsic::spv_lifetime_end: {
     unsigned Op = IID == Intrinsic::spv_lifetime_start ? SPIRV::OpLifetimeStart
diff --git a/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/rsqrt.ll b/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/rsqrt.ll
new file mode 100644
index 0000000..650b329
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/rsqrt.ll
@@ -0,0 +1,68 @@
+; RUN: llc -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-DAG: %[[#op_ext_glsl:]] = OpExtInstImport "GLSL.std.450"
+
+; CHECK-DAG: %[[#float_32:]] = OpTypeFloat 32
+; CHECK-DAG: %[[#float_16:]] = OpTypeFloat 16
+; CHECK-DAG: %[[#float_64:]] = OpTypeFloat 64
+
+; CHECK-DAG: %[[#vec4_float_32:]] = OpTypeVector %[[#float_32]] 4
+; CHECK-DAG: %[[#vec4_float_16:]] = OpTypeVector %[[#float_16]] 4
+; CHECK-DAG: %[[#vec4_float_64:]] = OpTypeVector %[[#float_64]] 4
+
+define noundef float @rsqrt_float(float noundef %a) {
+entry:
+; CHECK: %[[#float_32_arg:]] = OpFunctionParameter %[[#float_32]]
+; CHECK: %[[#]] = OpExtInst %[[#float_32]] %[[#op_ext_glsl]] InverseSqrt %[[#float_32_arg]]
+  %elt.rsqrt = call float @llvm.spv.rsqrt.f32(float %a)
+  ret float %elt.rsqrt
+}
+
+define noundef half @rsqrt_half(half noundef %a) {
+entry:
+; CHECK: %[[#float_16_arg:]] = OpFunctionParameter %[[#float_16]]
+; CHECK: %[[#]] = OpExtInst %[[#float_16]] %[[#op_ext_glsl]] InverseSqrt %[[#float_16_arg]]
+  %elt.rsqrt = call half @llvm.spv.rsqrt.f16(half %a)
+  ret half %elt.rsqrt
+}
+
+define noundef double @rsqrt_double(double noundef %a) {
+entry:
+; CHECK: %[[#float_64_arg:]] = OpFunctionParameter %[[#float_64]]
+; CHECK: %[[#]] = OpExtInst %[[#float_64]] %[[#op_ext_glsl]] InverseSqrt %[[#float_64_arg]]
+  %elt.rsqrt = call double @llvm.spv.rsqrt.f64(double %a)
+  ret double %elt.rsqrt
+}
+
+define noundef <4 x float> @rsqrt_float_vector(<4 x float> noundef %a) {
+entry:
+; CHECK: %[[#vec4_float_32_arg:]] = OpFunctionParameter %[[#vec4_float_32]]
+; CHECK: %[[#]] = OpExtInst %[[#vec4_float_32]] %[[#op_ext_glsl]] InverseSqrt %[[#vec4_float_32_arg]]
+  %elt.rsqrt = call <4 x float> @llvm.spv.rsqrt.v4f32(<4 x float> %a)
+  ret <4 x float> %elt.rsqrt
+}
+
+define noundef <4 x half> @rsqrt_half_vector(<4 x half> noundef %a) {
+entry:
+; CHECK: %[[#vec4_float_16_arg:]] = OpFunctionParameter %[[#vec4_float_16]]
+; CHECK: %[[#]] = OpExtInst %[[#vec4_float_16]] %[[#op_ext_glsl]] InverseSqrt %[[#vec4_float_16_arg]]
+  %elt.rsqrt = call <4 x half> @llvm.spv.rsqrt.v4f16(<4 x half> %a)
+  ret <4 x half> %elt.rsqrt
+}
+
+define noundef <4 x double> @rsqrt_double_vector(<4 x double> noundef %a) {
+entry:
+; CHECK: %[[#vec4_float_64_arg:]] = OpFunctionParameter %[[#vec4_float_64]]
+; CHECK: %[[#]] = OpExtInst %[[#vec4_float_64]] %[[#op_ext_glsl]] InverseSqrt %[[#vec4_float_64_arg]]
+  %elt.rsqrt = call <4 x double> @llvm.spv.rsqrt.v4f64(<4 x double> %a)
+  ret <4 x double> %elt.rsqrt
+}
+
+declare half @llvm.spv.rsqrt.f16(half)
+declare float @llvm.spv.rsqrt.f32(float)
+declare double @llvm.spv.rsqrt.f64(double)
+
+declare <4 x float> @llvm.spv.rsqrt.v4f32(<4 x float>)
+declare <4 x half> @llvm.spv.rsqrt.v4f16(<4 x half>)
+declare <4 x double> @llvm.spv.rsqrt.v4f64(<4 x double>)