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[HLSL] Add WaveGetLaneCount() intrinsic to FE #143127

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Merged
merged 2 commits into from
Jun 10, 2025
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[HLSL] Add WaveGetLaneCount() intrinsic to FE #143127

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d47adb2
[HLSL] Add WaveGetLaneCount() intrinsic to FE
Keenuts Jun 6, 2025
7865500
change bool to uint
Keenuts Jun 6, 2025
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6 changes: 6 additions & 0 deletions clang/include/clang/Basic/Builtins.td
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Original file line number Diff line number Diff line change
Expand Up @@ -4909,6 +4909,12 @@ def HLSLWaveReadLaneAt : LangBuiltin<"HLSL_LANG"> {
let Prototype = "void(...)";
}

def HLSLWaveGetLaneCount : LangBuiltin<"HLSL_LANG"> {
let Spellings = ["__builtin_hlsl_wave_get_lane_count"];
let Attributes = [NoThrow, Const];
let Prototype = "unsigned int()";
}

def HLSLClamp : LangBuiltin<"HLSL_LANG"> {
let Spellings = ["__builtin_hlsl_elementwise_clamp"];
let Attributes = [NoThrow, Const, CustomTypeChecking];
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5 changes: 5 additions & 0 deletions clang/lib/CodeGen/CGHLSLBuiltins.cpp
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Expand Up @@ -691,6 +691,11 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
return EmitRuntimeCall(
Intrinsic::getOrInsertDeclaration(&CGM.getModule(), ID));
}
case Builtin::BI__builtin_hlsl_wave_get_lane_count: {
Intrinsic::ID ID = CGM.getHLSLRuntime().getWaveGetLaneCountIntrinsic();
return EmitRuntimeCall(
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This is correct, just want to clarify the reason behind wave intrinsics being EmitRuntimeCall instead of Builder.CreateIntrinsic(.

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Reason why other wave intrinsics are using this instead of Builder.CreateIntrinsics are convergence intrinsics: correctly adding the token to the call.

Intrinsic::getOrInsertDeclaration(&CGM.getModule(), ID));
}
case Builtin::BI__builtin_hlsl_wave_read_lane_at: {
// Due to the use of variadic arguments we must explicitly retreive them and
// create our function type.
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1 change: 1 addition & 0 deletions clang/lib/CodeGen/CGHLSLRuntime.h
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Expand Up @@ -107,6 +107,7 @@ class CGHLSLRuntime {
GENERATE_HLSL_INTRINSIC_FUNCTION(WaveActiveAnyTrue, wave_any)
GENERATE_HLSL_INTRINSIC_FUNCTION(WaveActiveCountBits, wave_active_countbits)
GENERATE_HLSL_INTRINSIC_FUNCTION(WaveIsFirstLane, wave_is_first_lane)
GENERATE_HLSL_INTRINSIC_FUNCTION(WaveGetLaneCount, wave_get_lane_count)
GENERATE_HLSL_INTRINSIC_FUNCTION(WaveReadLaneAt, wave_readlane)
GENERATE_HLSL_INTRINSIC_FUNCTION(FirstBitUHigh, firstbituhigh)
GENERATE_HLSL_INTRINSIC_FUNCTION(FirstBitSHigh, firstbitshigh)
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4 changes: 4 additions & 0 deletions clang/lib/Headers/hlsl/hlsl_alias_intrinsics.h
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Expand Up @@ -2350,6 +2350,10 @@ _HLSL_AVAILABILITY(shadermodel, 6.0)
_HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_is_first_lane)
__attribute__((convergent)) bool WaveIsFirstLane();

_HLSL_AVAILABILITY(shadermodel, 6.0)
_HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_get_lane_count)
__attribute__((convergent)) uint WaveGetLaneCount();

//===----------------------------------------------------------------------===//
// WaveReadLaneAt builtins
//===----------------------------------------------------------------------===//
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32 changes: 32 additions & 0 deletions clang/test/CodeGenHLSL/builtins/wave_get_lane_count.hlsl
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@@ -0,0 +1,32 @@
// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
// RUN: spirv-pc-vulkan-compute %s -emit-llvm -disable-llvm-passes -o - | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-SPIRV
// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
// RUN: dxil-pc-shadermodel6.3-compute %s -emit-llvm -disable-llvm-passes -o - | \
// RUN: FileCheck %s --check-prefixes=CHECK,CHECK-DXIL

[numthreads(1, 1, 1)]
void main() {
uint a, b;
// CHECK-SPIRV: %[[#entry_tok:]] = call token @llvm.experimental.convergence.entry()

// CHECK-SPIRV: %[[#loop_tok:]] = call token @llvm.experimental.convergence.loop() [ "convergencectrl"(token %[[#entry_tok]]) ]
while (a) {

// CHECK-DXIL: %[[#]] = call i32 @llvm.dx.wave.get.lane.count()
// CHECK-SPIRV: %[[#]] = call spir_func i32 @llvm.spv.wave.get.lane.count()
// CHECK-SPIRV-SAME: [ "convergencectrl"(token %[[#loop_tok]]) ]
a = WaveGetLaneCount();
}

// CHECK-DXIL: %[[#]] = call i32 @llvm.dx.wave.get.lane.count()
// CHECK-SPIRV: %[[#]] = call spir_func i32 @llvm.spv.wave.get.lane.count()
// CHECK-SPIRV-SAME: [ "convergencectrl"(token %[[#entry_tok]]) ]
b = WaveGetLaneCount();
}

// CHECK-DXIL: i32 @llvm.dx.wave.get.lane.count() #[[#attr:]]
// CHECK-SPIRV: i32 @llvm.spv.wave.get.lane.count() #[[#attr:]]

// CHECK: attributes #[[#attr]] = {{{.*}} convergent {{.*}}}

2 changes: 2 additions & 0 deletions llvm/include/llvm/IR/IntrinsicsDirectX.td
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Expand Up @@ -148,6 +148,8 @@ def int_dx_wave_reduce_sum : DefaultAttrsIntrinsic<[llvm_any_ty], [LLVMMatchType
def int_dx_wave_reduce_usum : DefaultAttrsIntrinsic<[llvm_anyint_ty], [LLVMMatchType<0>], [IntrConvergent, IntrNoMem]>;
def int_dx_wave_is_first_lane : DefaultAttrsIntrinsic<[llvm_i1_ty], [], [IntrConvergent]>;
def int_dx_wave_readlane : DefaultAttrsIntrinsic<[llvm_any_ty], [LLVMMatchType<0>, llvm_i32_ty], [IntrConvergent, IntrNoMem]>;
def int_dx_wave_get_lane_count
: DefaultAttrsIntrinsic<[llvm_i32_ty], [], [IntrConvergent]>;
def int_dx_sign : DefaultAttrsIntrinsic<[LLVMScalarOrSameVectorWidth<0, llvm_i32_ty>], [llvm_any_ty], [IntrNoMem]>;
def int_dx_step : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty, LLVMMatchType<0>], [IntrNoMem]>;
def int_dx_splitdouble : DefaultAttrsIntrinsic<[llvm_anyint_ty, LLVMMatchType<0>],
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2 changes: 2 additions & 0 deletions llvm/include/llvm/IR/IntrinsicsSPIRV.td
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Expand Up @@ -102,6 +102,8 @@ let TargetPrefix = "spv" in {
def int_spv_wave_reduce_sum : DefaultAttrsIntrinsic<[llvm_any_ty], [LLVMMatchType<0>], [IntrConvergent, IntrNoMem]>;
def int_spv_wave_is_first_lane : DefaultAttrsIntrinsic<[llvm_i1_ty], [], [IntrConvergent]>;
def int_spv_wave_readlane : DefaultAttrsIntrinsic<[llvm_any_ty], [LLVMMatchType<0>, llvm_i32_ty], [IntrConvergent, IntrNoMem]>;
def int_spv_wave_get_lane_count
: DefaultAttrsIntrinsic<[llvm_i32_ty], [], [IntrConvergent]>;
def int_spv_sign : DefaultAttrsIntrinsic<[LLVMScalarOrSameVectorWidth<0, llvm_i32_ty>], [llvm_any_ty], [IntrNoMem]>;
def int_spv_radians : DefaultAttrsIntrinsic<[LLVMMatchType<0>], [llvm_anyfloat_ty], [IntrNoMem]>;
def int_spv_group_memory_barrier_with_group_sync : DefaultAttrsIntrinsic<[], [], []>;
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