Merge commit '374d5da214ba' from llvm.org/main into next

Author: git apple-llvm automerger

flang/test/Fir/invalid.fir

@@ -1426,12 +1426,3 @@ func.func @wrong_weights_number_in_if_then_else(%cond: i1) {
   }
   return
 }
-
-// -----
-
-func.func @negative_weight_in_if_then(%cond: i1) {
-// expected-error @below {{weight #0 must be non-negative}}
-  fir.if %cond weights([-1, 101]) {
-  }
-  return
-}

mlir/include/mlir/Interfaces/ControlFlowInterfaces.td

@@ -384,13 +384,15 @@ def WeightedBranchOpInterface : OpInterface<"WeightedBranchOpInterface"> {
     This interface provides weight information for branching terminator
     operations, i.e. terminator operations with successors.
 
-    This interface provides methods for getting/setting integer non-negative
-    weight of each branch. The probability of executing a branch
-    is computed as the ratio between the branch's weight and the total
-    sum of the weights (which cannot be zero).
-    The weights are optional. If they are provided, then their number
+    This interface provides methods for getting/setting integer weights of each
+    branch. The probability of executing a branch is computed as the ratio
+    between the branch's weight and the total sum of the weights (which cannot
+    be zero). The weights are optional. If they are provided, then their number
     must match the number of successors of the operation.
 
+    Note that the branch weight use an i32 representation but they are to be
+    interpreted as unsigned integers.
+
     The default implementations of the methods expect the operation
     to have an attribute of type DenseI32ArrayAttr named branch_weights.
   }];
@@ -440,19 +442,21 @@ def WeightedRegionBranchOpInterface
     This interface provides weight information for region operations
     that exhibit branching behavior between held regions.
 
-    This interface provides methods for getting/setting integer non-negative
-    weight of each branch. The probability of executing a region is computed
-    as the ratio between the region branch's weight and the total sum
-    of the weights (which cannot be zero).
-    The weights are optional. If they are provided, then their number
-    must match the number of regions held by the operation
-    (including empty regions).
+    This interface provides methods for getting/setting integer weights of each
+    branch. The probability of executing a region is computed as the ratio
+    between the region branch's weight and the total sum of the weights (which
+    cannot be zero). The weights are optional. If they are provided, then their
+    number must match the number of regions held by the operation (including
+    empty regions).
 
     The weights specify the probability of branching to a particular
     region when first executing the operation.
     For example, for loop-like operations with a single region
     the weight specifies the probability of entering the loop.
 
+    Note that the branch weight use an i32 representation but they are to be
+    interpreted as unsigned integers.
+
     The default implementations of the methods expect the operation
     to have an attribute of type DenseI32ArrayAttr named branch_weights.
   }];

mlir/lib/Interfaces/ControlFlowInterfaces.cpp

@@ -99,10 +99,6 @@ static LogicalResult verifyWeights(Operation *op,
                            << ": " << weights.size() << " vs "
                            << expectedWeightsNum;
 
-  for (auto [index, weight] : llvm::enumerate(weights))
-    if (weight < 0)
-      return op->emitError() << "weight #" << index << " must be non-negative";
-
   if (llvm::all_of(weights, [](int32_t value) { return value == 0; }))
     return op->emitError() << "branch weights cannot all be zero";
 

mlir/test/Dialect/ControlFlow/invalid.mlir

@@ -82,18 +82,6 @@ func.func @wrong_weights_number(%cond: i1) {
 
 // -----
 
-// CHECK-LABEL: func @negative_weight
-func.func @wrong_total_weight(%cond: i1) {
-  // expected-error@+1 {{weight #0 must be non-negative}}
-  cf.cond_br %cond weights([-1, 101]), ^bb1, ^bb2
-  ^bb1:
-    return
-  ^bb2:
-    return
-}
-
-// -----
-
 // CHECK-LABEL: func @zero_weights
 func.func @wrong_total_weight(%cond: i1) {
   // expected-error@+1 {{branch weights cannot all be zero}}