[mlir][gpu] Revert gpu.subgroup_broadcast with any_lane (#157373)

This partially reverts llvm/llvm-project#152808.

Post-commit comments revealed that the `any_lane` variant hasn't been
fully agreed upon at the time of landing.

Author: kuhar

mlir/include/mlir/Dialect/GPU/IR/GPUOps.td

@@ -3219,8 +3219,7 @@ def GPU_BroadcastType : I32EnumAttr<"BroadcastType",
     "a lane to broadcast from",
     [
       I32EnumAttrCase<"first_active_lane", 0>,
-      I32EnumAttrCase<"any_lane", 1>,
-      I32EnumAttrCase<"specific_lane", 2>
+      I32EnumAttrCase<"specific_lane", 1>
     ]>{
   let genSpecializedAttr = 0;
   let cppNamespace = "::mlir::gpu";
@@ -3248,13 +3247,6 @@ def GPU_SubgroupBroadcastOp : GPU_Op<"subgroup_broadcast",
       must be uniform and within the subgroup size. The result is poison if the
       lane index is invalid, non subgroup-uniform, or if the source lane is not
       active.
-      * `any_lane` - broadcasts the value from any lane of the subgroup,
-      assuming the input is already subgroup uniform. The result is poison if
-      the input is not uniform. This is useful to convey uniformity to the
-      compiler to enable more optimizations. Also, it allows more speculation
-      opportunities than `first_active_lane` since `first_active_lane` results
-      can depend on active lanes which may change during speculation across
-      control flow.
   }];
   let results = (outs AnyType:$result);
   let assemblyFormat = [{

mlir/lib/Conversion/GPUToROCDL/LowerGpuOpsToROCDLOps.cpp

@@ -193,9 +193,7 @@ struct GPUSubgroupBroadcastOpToROCDL
     if (adaptor.getBroadcastType() == gpu::BroadcastType::specific_lane) {
       rewriter.replaceOpWithNewOp<ROCDL::ReadlaneOp>(op, src.getType(), src,
                                                      adaptor.getLane());
-    } else { // first_active_lane or any_lane
-      // any_lane is lowered to readfirstlane too, to force value into scalar
-      // register.
+    } else { // first_active_lane
       rewriter.replaceOpWithNewOp<ROCDL::ReadfirstlaneOp>(op, src.getType(),
                                                           src);
     }

mlir/lib/Dialect/GPU/IR/GPUDialect.cpp

@@ -2529,8 +2529,6 @@ Speculation::Speculatability gpu::SubgroupBroadcastOp::getSpeculatability() {
     // Cannot speculate first_lane broadcast, because speculating it across
     // control flow can change the active lanes.
     return Speculation::NotSpeculatable;
-  case BroadcastType::any_lane:
-    LLVM_FALLTHROUGH;
   case BroadcastType::specific_lane:
     // Speculation should be safe as long as we inside structured control flow.
     return Speculation::Speculatable;
@@ -2540,8 +2538,6 @@ Speculation::Speculatability gpu::SubgroupBroadcastOp::getSpeculatability() {
 LogicalResult gpu::SubgroupBroadcastOp::verify() {
   switch (getBroadcastType()) {
   case BroadcastType::first_active_lane:
-    LLVM_FALLTHROUGH;
-  case BroadcastType::any_lane:
     if (getLane())
       return emitOpError()
              << "lane can only be specified for `specific_lane` broadcast";

mlir/test/Conversion/GPUToROCDL/gpu-to-rocdl.mlir

@@ -808,13 +808,11 @@ gpu.module @test_module {
 gpu.module @test_module {
 // CHECK-LABEL: func @broadcast
 //  CHECK-SAME:   (%[[ARG:.*]]: i64, %[[IDX:.*]]: i32)
-func.func @broadcast(%arg0 : index, %arg1 : i32) -> (index, index, index) {
-//       CHECK:   %{{.*}} = rocdl.readfirstlane %[[ARG]] : i64
+func.func @broadcast(%arg0 : index, %arg1 : i32) -> (index, index) {
 //       CHECK:   %{{.*}} = rocdl.readfirstlane %[[ARG]] : i64
 //       CHECK:   %{{.*}} = rocdl.readlane %[[ARG]], %[[IDX]] : (i64, i32) -> i64
   %0 = gpu.subgroup_broadcast %arg0, first_active_lane : index
-  %1 = gpu.subgroup_broadcast %arg0, any_lane : index
-  %2 = gpu.subgroup_broadcast %arg0, specific_lane %arg1 : index
-  func.return %0, %1, %2 : index, index, index
+  %1 = gpu.subgroup_broadcast %arg0, specific_lane %arg1 : index
+  func.return %0, %1 : index, index
 }
 }

mlir/test/Dialect/GPU/broadcast-speculatability.mlir

@@ -1,24 +1,22 @@
 // RUN: mlir-opt %s --loop-invariant-code-motion | FileCheck %s
 
-func.func private @side_effect(%arg0 : f32, %arg1 : f32, %arg2 : f32)
+func.func private @side_effect(%arg0 : f32, %arg1 : f32)
 
 // CHECK-LABEL: func @broadcast_hoisting
 //  CHECK-SAME: (%[[ARG:.*]]: f32, %[[IDX:.*]]: i32, {{.*}}: index)
 func.func @broadcast_hoisting(%arg0 : f32, %arg1 : i32, %arg2 : index) {
   %c0 = arith.constant 0 : index
   %c1 = arith.constant 1 : index
-// `any_lane` and `specific_lane` can be speculated across the control flow, but
+// `specific_lane` can be speculated across the control flow, but
 // `first_active_lane` cannot as active lanes can change.
-// CHECK: %[[V1:.*]] = gpu.subgroup_broadcast %[[ARG]], any_lane : f32
-// CHECK: %[[V2:.*]] = gpu.subgroup_broadcast %[[ARG]], specific_lane %[[IDX]] : f32
+// CHECK: %[[V1:.*]] = gpu.subgroup_broadcast %[[ARG]], specific_lane %[[IDX]] : f32
 // CHECK: scf.for
 // CHECK: %[[V0:.*]] = gpu.subgroup_broadcast %[[ARG]], first_active_lane : f32
-// CHECK: func.call @side_effect(%[[V0]], %[[V1]], %[[V2]])
+// CHECK: func.call @side_effect(%[[V0]], %[[V1]])
   scf.for %i = %c0 to %arg2 step %c1 {
     %0 = gpu.subgroup_broadcast %arg0, first_active_lane : f32
-    %1 = gpu.subgroup_broadcast %arg0, any_lane : f32
-    %2 = gpu.subgroup_broadcast %arg0, specific_lane %arg1 : f32
-    func.call @side_effect(%0, %1, %2) : (f32, f32, f32) -> ()
+    %1 = gpu.subgroup_broadcast %arg0, specific_lane %arg1 : f32
+    func.call @side_effect(%0, %1) : (f32, f32) -> ()
   }
   func.return
 }

mlir/test/Dialect/GPU/int-range-interface.mlir

@@ -336,15 +336,12 @@ module attributes {gpu.container_module} {
 func.func @broadcast(%idx: i32) {
   %0 = test.with_bounds { umin = 0 : index, umax = 10 : index, smin = 0 : index, smax = 10 : index } : index
   %1 = gpu.subgroup_broadcast %0, first_active_lane : index
-  %2 = gpu.subgroup_broadcast %0, any_lane : index
-  %3 = gpu.subgroup_broadcast %0, specific_lane %idx : index
+  %2 = gpu.subgroup_broadcast %0, specific_lane %idx : index
 
-  // CHECK: test.reflect_bounds {smax = 10 : index, smin = 0 : index, umax = 10 : index, umin = 0 : index}
   // CHECK: test.reflect_bounds {smax = 10 : index, smin = 0 : index, umax = 10 : index, umin = 0 : index}
   // CHECK: test.reflect_bounds {smax = 10 : index, smin = 0 : index, umax = 10 : index, umin = 0 : index}
 
   %4 = test.reflect_bounds %1 : index
   %5 = test.reflect_bounds %2 : index
-  %6 = test.reflect_bounds %3 : index
   return
 }

mlir/test/Dialect/GPU/ops.mlir

@@ -545,12 +545,10 @@ func.func @warp_operand_result(%laneid: index, %v0 : vector<4xi32>) -> (vector<4
 
 // CHECK-LABEL: func @subgroup_broadcast
 //  CHECK-SAME: (%[[ARG:.*]]: f32, %[[IDX:.*]]: i32)
-func.func @subgroup_broadcast(%arg0 : f32, %arg1 : i32) -> (f32, f32, f32) {
+func.func @subgroup_broadcast(%arg0 : f32, %arg1 : i32) -> (f32, f32) {
   // CHECK: gpu.subgroup_broadcast %[[ARG]], first_active_lane : f32
   %0 = gpu.subgroup_broadcast %arg0, first_active_lane : f32
-  // CHECK: gpu.subgroup_broadcast %[[ARG]], any_lane : f32
-  %1 = gpu.subgroup_broadcast %arg0, any_lane : f32
   // CHECK: gpu.subgroup_broadcast %[[ARG]], specific_lane %[[IDX]] : f32
-  %2 = gpu.subgroup_broadcast %arg0, specific_lane %arg1 : f32
-  func.return %0, %1, %2 : f32, f32, f32
+  %1 = gpu.subgroup_broadcast %arg0, specific_lane %arg1 : f32
+  func.return %0, %1 : f32, f32
 }