diff --git a/mlir/lib/Dialect/Affine/IR/AffineOps.cpp b/mlir/lib/Dialect/Affine/IR/AffineOps.cpp index 002f1f60bb58e..0c3592124cdec 100644 --- a/mlir/lib/Dialect/Affine/IR/AffineOps.cpp +++ b/mlir/lib/Dialect/Affine/IR/AffineOps.cpp @@ -2610,21 +2610,6 @@ static std::optional getTrivialConstantTripCount(AffineForOp forOp) { return ub - lb <= 0 ? 0 : (ub - lb + step - 1) / step; } -/// Calculate the constant value of the loop's induction variable for its last -/// trip. -static std::optional -getConstantInductionVarForLastTrip(AffineForOp forOp) { - std::optional tripCount = getTrivialConstantTripCount(forOp); - if (!tripCount.has_value()) - return std::nullopt; - if (tripCount.value() == 0) - return std::nullopt; - int64_t lb = forOp.getConstantLowerBound(); - int64_t step = forOp.getStepAsInt(); - int64_t lastTripIv = lb + (tripCount.value() - 1) * step; - return lastTripIv; -} - /// Fold the empty loop. static SmallVector AffineForEmptyLoopFolder(AffineForOp forOp) { if (!llvm::hasSingleElement(*forOp.getBody())) @@ -2637,7 +2622,7 @@ static SmallVector AffineForEmptyLoopFolder(AffineForOp forOp) { // results. return forOp.getInits(); } - SmallVector replacements; + SmallVector replacements; auto yieldOp = cast(forOp.getBody()->getTerminator()); auto iterArgs = forOp.getRegionIterArgs(); bool hasValDefinedOutsideLoop = false; @@ -2645,14 +2630,10 @@ static SmallVector AffineForEmptyLoopFolder(AffineForOp forOp) { for (unsigned i = 0, e = yieldOp->getNumOperands(); i < e; ++i) { Value val = yieldOp.getOperand(i); BlockArgument *iterArgIt = llvm::find(iterArgs, val); - if (val == forOp.getInductionVar()) { - if (auto lastTripIv = getConstantInductionVarForLastTrip(forOp)) { - replacements.push_back(IntegerAttr::get( - IndexType::get(forOp.getContext()), lastTripIv.value())); - continue; - } + // TODO: It should be possible to perform a replacement by computing the + // last value of the IV based on the bounds and the step. + if (val == forOp.getInductionVar()) return {}; - } if (iterArgIt == iterArgs.end()) { // `val` is defined outside of the loop. assert(forOp.isDefinedOutsideOfLoop(val) && @@ -2675,7 +2656,7 @@ static SmallVector AffineForEmptyLoopFolder(AffineForOp forOp) { // out of order. if (tripCount.has_value() && tripCount.value() >= 2 && iterArgsNotInOrder) return {}; - return replacements; + return llvm::to_vector_of(replacements); } /// Canonicalize the bounds of the given loop. diff --git a/mlir/test/Dialect/Affine/canonicalize.mlir b/mlir/test/Dialect/Affine/canonicalize.mlir index 997f23b4bd669..1169cd1c29d74 100644 --- a/mlir/test/Dialect/Affine/canonicalize.mlir +++ b/mlir/test/Dialect/Affine/canonicalize.mlir @@ -609,19 +609,6 @@ func.func @fold_zero_iter_loops(%in : index) -> index { // ----- -// CHECK-LABEL: func @fold_empty_loop_iv -// CHECK-SAME: %[[INIT:.*]]: index -func.func @fold_empty_loop_iv(%init: index) -> (index, index) { - %res:2 = affine.for %i = 0 to 10 step 1 iter_args(%arg0 = %init, %arg1 = %init) -> (index, index) { - affine.yield %i, %arg1 : index, index - } - // CHECK: %[[C9:.*]] = arith.constant 9 : index - // CHECK: return %[[C9]], %[[INIT]] : index, index - return %res#0, %res#1 : index, index -} - -// ----- - // CHECK-DAG: #[[$SET:.*]] = affine_set<(d0, d1)[s0] : (d0 >= 0, -d0 + 1022 >= 0, d1 >= 0, -d1 + s0 - 2 >= 0)> // CHECK-LABEL: func @canonicalize_affine_if