[Mlir-commits] [mlir] dc4786b - [mlir][affine] remove divide zero check when simplifer affineMap (#64622) (#68519)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Sat Nov 18 10:14:58 PST 2023
Author: long.chen
Date: 2023-11-19T02:14:53+08:00
New Revision: dc4786b4877d67d73d3892c45baf6811af0e6f57
URL: https://github.com/llvm/llvm-project/commit/dc4786b4877d67d73d3892c45baf6811af0e6f57
DIFF: https://github.com/llvm/llvm-project/commit/dc4786b4877d67d73d3892c45baf6811af0e6f57.diff
LOG: [mlir][affine] remove divide zero check when simplifer affineMap (#64622) (#68519)
When performing constant folding on the affineApplyOp, there is a
division of 0 in the affine map.
[related issue](https://github.com/llvm/llvm-project/issues/64622)
---------
Co-authored-by: Javier Setoain <jsetoain at users.noreply.github.com>
Added:
Modified:
mlir/include/mlir/IR/AffineExprVisitor.h
mlir/include/mlir/IR/AffineMap.h
mlir/lib/Analysis/FlatLinearValueConstraints.cpp
mlir/lib/Dialect/Affine/IR/AffineOps.cpp
mlir/lib/Dialect/Affine/IR/CMakeLists.txt
mlir/lib/IR/AffineExpr.cpp
mlir/lib/IR/AffineMap.cpp
mlir/test/Dialect/Affine/constant-fold.mlir
Removed:
################################################################################
diff --git a/mlir/include/mlir/IR/AffineExprVisitor.h b/mlir/include/mlir/IR/AffineExprVisitor.h
index 382db22dce463e5..2860e73c8f42839 100644
--- a/mlir/include/mlir/IR/AffineExprVisitor.h
+++ b/mlir/include/mlir/IR/AffineExprVisitor.h
@@ -14,6 +14,7 @@
#define MLIR_IR_AFFINEEXPRVISITOR_H
#include "mlir/IR/AffineExpr.h"
+#include "mlir/Support/LogicalResult.h"
#include "llvm/ADT/ArrayRef.h"
namespace mlir {
@@ -65,8 +66,78 @@ namespace mlir {
/// just as efficient as having your own switch instruction over the instruction
/// opcode.
+template <typename SubClass, typename RetTy>
+class AffineExprVisitorBase {
+public:
+ // Function to visit an AffineExpr.
+ RetTy visit(AffineExpr expr) {
+ static_assert(std::is_base_of<AffineExprVisitorBase, SubClass>::value,
+ "Must instantiate with a derived type of AffineExprVisitor");
+ auto self = static_cast<SubClass *>(this);
+ switch (expr.getKind()) {
+ case AffineExprKind::Add: {
+ auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
+ return self->visitAddExpr(binOpExpr);
+ }
+ case AffineExprKind::Mul: {
+ auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
+ return self->visitMulExpr(binOpExpr);
+ }
+ case AffineExprKind::Mod: {
+ auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
+ return self->visitModExpr(binOpExpr);
+ }
+ case AffineExprKind::FloorDiv: {
+ auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
+ return self->visitFloorDivExpr(binOpExpr);
+ }
+ case AffineExprKind::CeilDiv: {
+ auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
+ return self->visitCeilDivExpr(binOpExpr);
+ }
+ case AffineExprKind::Constant:
+ return self->visitConstantExpr(cast<AffineConstantExpr>(expr));
+ case AffineExprKind::DimId:
+ return self->visitDimExpr(cast<AffineDimExpr>(expr));
+ case AffineExprKind::SymbolId:
+ return self->visitSymbolExpr(cast<AffineSymbolExpr>(expr));
+ }
+ llvm_unreachable("Unknown AffineExpr");
+ }
+
+ //===--------------------------------------------------------------------===//
+ // Visitation functions... these functions provide default fallbacks in case
+ // the user does not specify what to do for a particular instruction type.
+ // The default behavior is to generalize the instruction type to its subtype
+ // and try visiting the subtype. All of this should be inlined perfectly,
+ // because there are no virtual functions to get in the way.
+ //
+
+ // Default visit methods. Note that the default op-specific binary op visit
+ // methods call the general visitAffineBinaryOpExpr visit method.
+ RetTy visitAffineBinaryOpExpr(AffineBinaryOpExpr expr) { return RetTy(); }
+ RetTy visitAddExpr(AffineBinaryOpExpr expr) {
+ return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
+ }
+ RetTy visitMulExpr(AffineBinaryOpExpr expr) {
+ return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
+ }
+ RetTy visitModExpr(AffineBinaryOpExpr expr) {
+ return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
+ }
+ RetTy visitFloorDivExpr(AffineBinaryOpExpr expr) {
+ return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
+ }
+ RetTy visitCeilDivExpr(AffineBinaryOpExpr expr) {
+ return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
+ }
+ RetTy visitConstantExpr(AffineConstantExpr expr) { return RetTy(); }
+ RetTy visitDimExpr(AffineDimExpr expr) { return RetTy(); }
+ RetTy visitSymbolExpr(AffineSymbolExpr expr) { return RetTy(); }
+};
+
template <typename SubClass, typename RetTy = void>
-class AffineExprVisitor {
+class AffineExprVisitor : public AffineExprVisitorBase<SubClass, RetTy> {
//===--------------------------------------------------------------------===//
// Interface code - This is the public interface of the AffineExprVisitor
// that you use to visit affine expressions...
@@ -75,117 +146,112 @@ class AffineExprVisitor {
RetTy walkPostOrder(AffineExpr expr) {
static_assert(std::is_base_of<AffineExprVisitor, SubClass>::value,
"Must instantiate with a derived type of AffineExprVisitor");
+ auto self = static_cast<SubClass *>(this);
switch (expr.getKind()) {
case AffineExprKind::Add: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
walkOperandsPostOrder(binOpExpr);
- return static_cast<SubClass *>(this)->visitAddExpr(binOpExpr);
+ return self->visitAddExpr(binOpExpr);
}
case AffineExprKind::Mul: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
walkOperandsPostOrder(binOpExpr);
- return static_cast<SubClass *>(this)->visitMulExpr(binOpExpr);
+ return self->visitMulExpr(binOpExpr);
}
case AffineExprKind::Mod: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
walkOperandsPostOrder(binOpExpr);
- return static_cast<SubClass *>(this)->visitModExpr(binOpExpr);
+ return self->visitModExpr(binOpExpr);
}
case AffineExprKind::FloorDiv: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
walkOperandsPostOrder(binOpExpr);
- return static_cast<SubClass *>(this)->visitFloorDivExpr(binOpExpr);
+ return self->visitFloorDivExpr(binOpExpr);
}
case AffineExprKind::CeilDiv: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
walkOperandsPostOrder(binOpExpr);
- return static_cast<SubClass *>(this)->visitCeilDivExpr(binOpExpr);
+ return self->visitCeilDivExpr(binOpExpr);
}
case AffineExprKind::Constant:
- return static_cast<SubClass *>(this)->visitConstantExpr(
- cast<AffineConstantExpr>(expr));
+ return self->visitConstantExpr(cast<AffineConstantExpr>(expr));
case AffineExprKind::DimId:
- return static_cast<SubClass *>(this)->visitDimExpr(
- cast<AffineDimExpr>(expr));
+ return self->visitDimExpr(cast<AffineDimExpr>(expr));
case AffineExprKind::SymbolId:
- return static_cast<SubClass *>(this)->visitSymbolExpr(
- cast<AffineSymbolExpr>(expr));
+ return self->visitSymbolExpr(cast<AffineSymbolExpr>(expr));
}
+ llvm_unreachable("Unknown AffineExpr");
}
- // Function to visit an AffineExpr.
- RetTy visit(AffineExpr expr) {
+private:
+ // Walk the operands - each operand is itself walked in post order.
+ RetTy walkOperandsPostOrder(AffineBinaryOpExpr expr) {
+ walkPostOrder(expr.getLHS());
+ walkPostOrder(expr.getRHS());
+ }
+};
+
+template <typename SubClass>
+class AffineExprVisitor<SubClass, LogicalResult>
+ : public AffineExprVisitorBase<SubClass, LogicalResult> {
+ //===--------------------------------------------------------------------===//
+ // Interface code - This is the public interface of the AffineExprVisitor
+ // that you use to visit affine expressions...
+public:
+ // Function to walk an AffineExpr (in post order).
+ LogicalResult walkPostOrder(AffineExpr expr) {
static_assert(std::is_base_of<AffineExprVisitor, SubClass>::value,
"Must instantiate with a derived type of AffineExprVisitor");
+ auto self = static_cast<SubClass *>(this);
switch (expr.getKind()) {
case AffineExprKind::Add: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
- return static_cast<SubClass *>(this)->visitAddExpr(binOpExpr);
+ if (failed(walkOperandsPostOrder(binOpExpr)))
+ return failure();
+ return self->visitAddExpr(binOpExpr);
}
case AffineExprKind::Mul: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
- return static_cast<SubClass *>(this)->visitMulExpr(binOpExpr);
+ if (failed(walkOperandsPostOrder(binOpExpr)))
+ return failure();
+ return self->visitMulExpr(binOpExpr);
}
case AffineExprKind::Mod: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
- return static_cast<SubClass *>(this)->visitModExpr(binOpExpr);
+ if (failed(walkOperandsPostOrder(binOpExpr)))
+ return failure();
+ return self->visitModExpr(binOpExpr);
}
case AffineExprKind::FloorDiv: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
- return static_cast<SubClass *>(this)->visitFloorDivExpr(binOpExpr);
+ if (failed(walkOperandsPostOrder(binOpExpr)))
+ return failure();
+ return self->visitFloorDivExpr(binOpExpr);
}
case AffineExprKind::CeilDiv: {
auto binOpExpr = cast<AffineBinaryOpExpr>(expr);
- return static_cast<SubClass *>(this)->visitCeilDivExpr(binOpExpr);
+ if (failed(walkOperandsPostOrder(binOpExpr)))
+ return failure();
+ return self->visitCeilDivExpr(binOpExpr);
}
case AffineExprKind::Constant:
- return static_cast<SubClass *>(this)->visitConstantExpr(
- cast<AffineConstantExpr>(expr));
+ return self->visitConstantExpr(cast<AffineConstantExpr>(expr));
case AffineExprKind::DimId:
- return static_cast<SubClass *>(this)->visitDimExpr(
- cast<AffineDimExpr>(expr));
+ return self->visitDimExpr(cast<AffineDimExpr>(expr));
case AffineExprKind::SymbolId:
- return static_cast<SubClass *>(this)->visitSymbolExpr(
- cast<AffineSymbolExpr>(expr));
+ return self->visitSymbolExpr(cast<AffineSymbolExpr>(expr));
}
llvm_unreachable("Unknown AffineExpr");
}
- //===--------------------------------------------------------------------===//
- // Visitation functions... these functions provide default fallbacks in case
- // the user does not specify what to do for a particular instruction type.
- // The default behavior is to generalize the instruction type to its subtype
- // and try visiting the subtype. All of this should be inlined perfectly,
- // because there are no virtual functions to get in the way.
- //
-
- // Default visit methods. Note that the default op-specific binary op visit
- // methods call the general visitAffineBinaryOpExpr visit method.
- RetTy visitAffineBinaryOpExpr(AffineBinaryOpExpr expr) { return RetTy(); }
- RetTy visitAddExpr(AffineBinaryOpExpr expr) {
- return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
- }
- RetTy visitMulExpr(AffineBinaryOpExpr expr) {
- return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
- }
- RetTy visitModExpr(AffineBinaryOpExpr expr) {
- return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
- }
- RetTy visitFloorDivExpr(AffineBinaryOpExpr expr) {
- return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
- }
- RetTy visitCeilDivExpr(AffineBinaryOpExpr expr) {
- return static_cast<SubClass *>(this)->visitAffineBinaryOpExpr(expr);
- }
- RetTy visitConstantExpr(AffineConstantExpr expr) { return RetTy(); }
- RetTy visitDimExpr(AffineDimExpr expr) { return RetTy(); }
- RetTy visitSymbolExpr(AffineSymbolExpr expr) { return RetTy(); }
-
private:
// Walk the operands - each operand is itself walked in post order.
- RetTy walkOperandsPostOrder(AffineBinaryOpExpr expr) {
- walkPostOrder(expr.getLHS());
- walkPostOrder(expr.getRHS());
+ LogicalResult walkOperandsPostOrder(AffineBinaryOpExpr expr) {
+ if (failed(walkPostOrder(expr.getLHS())))
+ return failure();
+ if (failed(walkPostOrder(expr.getRHS())))
+ return failure();
+ return success();
}
};
@@ -246,7 +312,7 @@ class AffineExprVisitor {
// expressions are mapped to the same local identifier (same column position in
// 'localVarCst').
class SimpleAffineExprFlattener
- : public AffineExprVisitor<SimpleAffineExprFlattener> {
+ : public AffineExprVisitor<SimpleAffineExprFlattener, LogicalResult> {
public:
// Flattend expression layout: [dims, symbols, locals, constant]
// Stack that holds the LHS and RHS operands while visiting a binary op expr.
@@ -275,13 +341,13 @@ class SimpleAffineExprFlattener
virtual ~SimpleAffineExprFlattener() = default;
// Visitor method overrides.
- void visitMulExpr(AffineBinaryOpExpr expr);
- void visitAddExpr(AffineBinaryOpExpr expr);
- void visitDimExpr(AffineDimExpr expr);
- void visitSymbolExpr(AffineSymbolExpr expr);
- void visitConstantExpr(AffineConstantExpr expr);
- void visitCeilDivExpr(AffineBinaryOpExpr expr);
- void visitFloorDivExpr(AffineBinaryOpExpr expr);
+ LogicalResult visitMulExpr(AffineBinaryOpExpr expr);
+ LogicalResult visitAddExpr(AffineBinaryOpExpr expr);
+ LogicalResult visitDimExpr(AffineDimExpr expr);
+ LogicalResult visitSymbolExpr(AffineSymbolExpr expr);
+ LogicalResult visitConstantExpr(AffineConstantExpr expr);
+ LogicalResult visitCeilDivExpr(AffineBinaryOpExpr expr);
+ LogicalResult visitFloorDivExpr(AffineBinaryOpExpr expr);
//
// t = expr mod c <=> t = expr - c*q and c*q <= expr <= c*q + c - 1
@@ -289,7 +355,7 @@ class SimpleAffineExprFlattener
// A mod expression "expr mod c" is thus flattened by introducing a new local
// variable q (= expr floordiv c), such that expr mod c is replaced with
// 'expr - c * q' and c * q <= expr <= c * q + c - 1 are added to localVarCst.
- void visitModExpr(AffineBinaryOpExpr expr);
+ LogicalResult visitModExpr(AffineBinaryOpExpr expr);
protected:
// Add a local identifier (needed to flatten a mod, floordiv, ceildiv expr).
@@ -328,7 +394,7 @@ class SimpleAffineExprFlattener
//
// A ceildiv is similarly flattened:
// t = expr ceildiv c <=> t = (expr + c - 1) floordiv c
- void visitDivExpr(AffineBinaryOpExpr expr, bool isCeil);
+ LogicalResult visitDivExpr(AffineBinaryOpExpr expr, bool isCeil);
int findLocalId(AffineExpr localExpr);
diff --git a/mlir/include/mlir/IR/AffineMap.h b/mlir/include/mlir/IR/AffineMap.h
index 713aef767edf669..0e4a8d363946432 100644
--- a/mlir/include/mlir/IR/AffineMap.h
+++ b/mlir/include/mlir/IR/AffineMap.h
@@ -310,7 +310,8 @@ class AffineMap {
/// Folds the results of the application of an affine map on the provided
/// operands to a constant if possible.
LogicalResult constantFold(ArrayRef<Attribute> operandConstants,
- SmallVectorImpl<Attribute> &results) const;
+ SmallVectorImpl<Attribute> &results,
+ bool *hasPoison = nullptr) const;
/// Propagates the constant operands into this affine map. Operands are
/// allowed to be null, at which point they are treated as non-constant. This
@@ -318,9 +319,9 @@ class AffineMap {
/// which may be equal to the old map if no folding happened. If `results` is
/// provided and if all expressions in the map were folded to constants,
/// `results` will contain the values of these constants.
- AffineMap
- partialConstantFold(ArrayRef<Attribute> operandConstants,
- SmallVectorImpl<int64_t> *results = nullptr) const;
+ AffineMap partialConstantFold(ArrayRef<Attribute> operandConstants,
+ SmallVectorImpl<int64_t> *results = nullptr,
+ bool *hasPoison = nullptr) const;
/// Returns the AffineMap resulting from composing `this` with `map`.
/// The resulting AffineMap has as many AffineDimExpr as `map` and as many
diff --git a/mlir/lib/Analysis/FlatLinearValueConstraints.cpp b/mlir/lib/Analysis/FlatLinearValueConstraints.cpp
index ea123ea56025b2f..69846a356e0cc42 100644
--- a/mlir/lib/Analysis/FlatLinearValueConstraints.cpp
+++ b/mlir/lib/Analysis/FlatLinearValueConstraints.cpp
@@ -67,7 +67,9 @@ struct AffineExprFlattener : public SimpleAffineExprFlattener {
} // namespace
// Flattens the expressions in map. Returns failure if 'expr' was unable to be
-// flattened (i.e., semi-affine expressions not handled yet).
+// flattened. For example two specific cases:
+// 1. semi-affine expressions not handled yet.
+// 2. has poison expression (i.e., division by zero).
static LogicalResult
getFlattenedAffineExprs(ArrayRef<AffineExpr> exprs, unsigned numDims,
unsigned numSymbols,
@@ -85,8 +87,10 @@ getFlattenedAffineExprs(ArrayRef<AffineExpr> exprs, unsigned numDims,
for (auto expr : exprs) {
if (!expr.isPureAffine())
return failure();
-
- flattener.walkPostOrder(expr);
+ // has poison expression
+ auto flattenResult = flattener.walkPostOrder(expr);
+ if (failed(flattenResult))
+ return failure();
}
assert(flattener.operandExprStack.size() == exprs.size());
diff --git a/mlir/lib/Dialect/Affine/IR/AffineOps.cpp b/mlir/lib/Dialect/Affine/IR/AffineOps.cpp
index 05496e70716a2a1..d22a7539fb75018 100644
--- a/mlir/lib/Dialect/Affine/IR/AffineOps.cpp
+++ b/mlir/lib/Dialect/Affine/IR/AffineOps.cpp
@@ -9,6 +9,7 @@
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Affine/IR/AffineValueMap.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
+#include "mlir/Dialect/UB/IR/UBOps.h"
#include "mlir/IR/AffineExprVisitor.h"
#include "mlir/IR/IRMapping.h"
#include "mlir/IR/IntegerSet.h"
@@ -226,6 +227,8 @@ void AffineDialect::initialize() {
Operation *AffineDialect::materializeConstant(OpBuilder &builder,
Attribute value, Type type,
Location loc) {
+ if (auto poison = dyn_cast<ub::PoisonAttr>(value))
+ return builder.create<ub::PoisonOp>(loc, type, poison);
return arith::ConstantOp::materialize(builder, value, type, loc);
}
@@ -580,7 +583,12 @@ OpFoldResult AffineApplyOp::fold(FoldAdaptor adaptor) {
// Otherwise, default to folding the map.
SmallVector<Attribute, 1> result;
- if (failed(map.constantFold(adaptor.getMapOperands(), result)))
+ bool hasPoison = false;
+ auto foldResult =
+ map.constantFold(adaptor.getMapOperands(), result, &hasPoison);
+ if (hasPoison)
+ return ub::PoisonAttr::get(getContext());
+ if (failed(foldResult))
return {};
return result[0];
}
@@ -3379,7 +3387,9 @@ static LogicalResult canonicalizeMapExprAndTermOrder(AffineMap &map) {
return failure();
SimpleAffineExprFlattener flattener(map.getNumDims(), map.getNumSymbols());
- flattener.walkPostOrder(resultExpr);
+ auto flattenResult = flattener.walkPostOrder(resultExpr);
+ if (failed(flattenResult))
+ return failure();
// Fail if the flattened expression has local variables.
if (flattener.operandExprStack.back().size() !=
diff --git a/mlir/lib/Dialect/Affine/IR/CMakeLists.txt b/mlir/lib/Dialect/Affine/IR/CMakeLists.txt
index 89ea3128b0e743f..9e3c1161fd92a09 100644
--- a/mlir/lib/Dialect/Affine/IR/CMakeLists.txt
+++ b/mlir/lib/Dialect/Affine/IR/CMakeLists.txt
@@ -19,5 +19,6 @@ add_mlir_dialect_library(MLIRAffineDialect
MLIRMemRefDialect
MLIRShapedOpInterfaces
MLIRSideEffectInterfaces
+ MLIRUBDialect
MLIRValueBoundsOpInterface
)
diff --git a/mlir/lib/IR/AffineExpr.cpp b/mlir/lib/IR/AffineExpr.cpp
index cdceaac11069815..038ceea286a363f 100644
--- a/mlir/lib/IR/AffineExpr.cpp
+++ b/mlir/lib/IR/AffineExpr.cpp
@@ -1216,7 +1216,7 @@ SimpleAffineExprFlattener::SimpleAffineExprFlattener(unsigned numDims,
// In case of semi affine multiplication expressions, t = expr * symbolic_expr,
// introduce a local variable p (= expr * symbolic_expr), and the affine
// expression expr * symbolic_expr is added to `localExprs`.
-void SimpleAffineExprFlattener::visitMulExpr(AffineBinaryOpExpr expr) {
+LogicalResult SimpleAffineExprFlattener::visitMulExpr(AffineBinaryOpExpr expr) {
assert(operandExprStack.size() >= 2);
SmallVector<int64_t, 8> rhs = operandExprStack.back();
operandExprStack.pop_back();
@@ -1232,7 +1232,7 @@ void SimpleAffineExprFlattener::visitMulExpr(AffineBinaryOpExpr expr) {
AffineExpr b = getAffineExprFromFlatForm(rhs, numDims, numSymbols,
localExprs, context);
addLocalVariableSemiAffine(a * b, lhs, lhs.size());
- return;
+ return success();
}
// Get the RHS constant.
@@ -1240,9 +1240,10 @@ void SimpleAffineExprFlattener::visitMulExpr(AffineBinaryOpExpr expr) {
for (unsigned i = 0, e = lhs.size(); i < e; i++) {
lhs[i] *= rhsConst;
}
+ return success();
}
-void SimpleAffineExprFlattener::visitAddExpr(AffineBinaryOpExpr expr) {
+LogicalResult SimpleAffineExprFlattener::visitAddExpr(AffineBinaryOpExpr expr) {
assert(operandExprStack.size() >= 2);
const auto &rhs = operandExprStack.back();
auto &lhs = operandExprStack[operandExprStack.size() - 2];
@@ -1253,6 +1254,7 @@ void SimpleAffineExprFlattener::visitAddExpr(AffineBinaryOpExpr expr) {
}
// Pop off the RHS.
operandExprStack.pop_back();
+ return success();
}
//
@@ -1265,7 +1267,7 @@ void SimpleAffineExprFlattener::visitAddExpr(AffineBinaryOpExpr expr) {
// In case of semi-affine modulo expressions, t = expr mod symbolic_expr,
// introduce a local variable m (= expr mod symbolic_expr), and the affine
// expression expr mod symbolic_expr is added to `localExprs`.
-void SimpleAffineExprFlattener::visitModExpr(AffineBinaryOpExpr expr) {
+LogicalResult SimpleAffineExprFlattener::visitModExpr(AffineBinaryOpExpr expr) {
assert(operandExprStack.size() >= 2);
SmallVector<int64_t, 8> rhs = operandExprStack.back();
@@ -1283,13 +1285,12 @@ void SimpleAffineExprFlattener::visitModExpr(AffineBinaryOpExpr expr) {
localExprs, context);
AffineExpr modExpr = dividendExpr % divisorExpr;
addLocalVariableSemiAffine(modExpr, lhs, lhs.size());
- return;
+ return success();
}
int64_t rhsConst = rhs[getConstantIndex()];
- // TODO: handle modulo by zero case when this issue is fixed
- // at the other places in the IR.
- assert(rhsConst > 0 && "RHS constant has to be positive");
+ if (rhsConst <= 0)
+ return failure();
// Check if the LHS expression is a multiple of modulo factor.
unsigned i, e;
@@ -1299,7 +1300,7 @@ void SimpleAffineExprFlattener::visitModExpr(AffineBinaryOpExpr expr) {
// If yes, modulo expression here simplifies to zero.
if (i == lhs.size()) {
std::fill(lhs.begin(), lhs.end(), 0);
- return;
+ return success();
}
// Add a local variable for the quotient, i.e., expr % c is replaced by
@@ -1331,33 +1332,41 @@ void SimpleAffineExprFlattener::visitModExpr(AffineBinaryOpExpr expr) {
// Reuse the existing local id.
lhs[getLocalVarStartIndex() + loc] = -rhsConst;
}
+ return success();
}
-void SimpleAffineExprFlattener::visitCeilDivExpr(AffineBinaryOpExpr expr) {
- visitDivExpr(expr, /*isCeil=*/true);
+LogicalResult
+SimpleAffineExprFlattener::visitCeilDivExpr(AffineBinaryOpExpr expr) {
+ return visitDivExpr(expr, /*isCeil=*/true);
}
-void SimpleAffineExprFlattener::visitFloorDivExpr(AffineBinaryOpExpr expr) {
- visitDivExpr(expr, /*isCeil=*/false);
+LogicalResult
+SimpleAffineExprFlattener::visitFloorDivExpr(AffineBinaryOpExpr expr) {
+ return visitDivExpr(expr, /*isCeil=*/false);
}
-void SimpleAffineExprFlattener::visitDimExpr(AffineDimExpr expr) {
+LogicalResult SimpleAffineExprFlattener::visitDimExpr(AffineDimExpr expr) {
operandExprStack.emplace_back(SmallVector<int64_t, 32>(getNumCols(), 0));
auto &eq = operandExprStack.back();
assert(expr.getPosition() < numDims && "Inconsistent number of dims");
eq[getDimStartIndex() + expr.getPosition()] = 1;
+ return success();
}
-void SimpleAffineExprFlattener::visitSymbolExpr(AffineSymbolExpr expr) {
+LogicalResult
+SimpleAffineExprFlattener::visitSymbolExpr(AffineSymbolExpr expr) {
operandExprStack.emplace_back(SmallVector<int64_t, 32>(getNumCols(), 0));
auto &eq = operandExprStack.back();
assert(expr.getPosition() < numSymbols && "inconsistent number of symbols");
eq[getSymbolStartIndex() + expr.getPosition()] = 1;
+ return success();
}
-void SimpleAffineExprFlattener::visitConstantExpr(AffineConstantExpr expr) {
+LogicalResult
+SimpleAffineExprFlattener::visitConstantExpr(AffineConstantExpr expr) {
operandExprStack.emplace_back(SmallVector<int64_t, 32>(getNumCols(), 0));
auto &eq = operandExprStack.back();
eq[getConstantIndex()] = expr.getValue();
+ return success();
}
void SimpleAffineExprFlattener::addLocalVariableSemiAffine(
@@ -1388,8 +1397,8 @@ void SimpleAffineExprFlattener::addLocalVariableSemiAffine(
// or t = expr ceildiv symbolic_expr, introduce a local variable q (= expr
// floordiv/ceildiv symbolic_expr), and the affine floordiv/ceildiv is added to
// `localExprs`.
-void SimpleAffineExprFlattener::visitDivExpr(AffineBinaryOpExpr expr,
- bool isCeil) {
+LogicalResult SimpleAffineExprFlattener::visitDivExpr(AffineBinaryOpExpr expr,
+ bool isCeil) {
assert(operandExprStack.size() >= 2);
MLIRContext *context = expr.getContext();
@@ -1407,14 +1416,13 @@ void SimpleAffineExprFlattener::visitDivExpr(AffineBinaryOpExpr expr,
localExprs, context);
AffineExpr divExpr = isCeil ? a.ceilDiv(b) : a.floorDiv(b);
addLocalVariableSemiAffine(divExpr, lhs, lhs.size());
- return;
+ return success();
}
// This is a pure affine expr; the RHS is a positive constant.
int64_t rhsConst = rhs[getConstantIndex()];
- // TODO: handle division by zero at the same time the issue is
- // fixed at other places.
- assert(rhsConst > 0 && "RHS constant has to be positive");
+ if (rhsConst <= 0)
+ return failure();
// Simplify the floordiv, ceildiv if possible by canceling out the greatest
// common divisors of the numerator and denominator.
@@ -1430,7 +1438,7 @@ void SimpleAffineExprFlattener::visitDivExpr(AffineBinaryOpExpr expr,
// If the divisor becomes 1, the updated LHS is the result. (The
// divisor can't be negative since rhsConst is positive).
if (divisor == 1)
- return;
+ return success();
// If the divisor cannot be simplified to one, we will have to retain
// the ceil/floor expr (simplified up until here). Add an existential
@@ -1460,6 +1468,7 @@ void SimpleAffineExprFlattener::visitDivExpr(AffineBinaryOpExpr expr,
lhs[getLocalVarStartIndex() + numLocals - 1] = 1;
else
lhs[getLocalVarStartIndex() + loc] = 1;
+ return success();
}
// Add a local identifier (needed to flatten a mod, floordiv, ceildiv expr).
@@ -1500,7 +1509,9 @@ AffineExpr mlir::simplifyAffineExpr(AffineExpr expr, unsigned numDims,
expr = simplifySemiAffine(expr, numDims, numSymbols);
SimpleAffineExprFlattener flattener(numDims, numSymbols);
- flattener.walkPostOrder(expr);
+ // has poison expression
+ if (failed(flattener.walkPostOrder(expr)))
+ return expr;
ArrayRef<int64_t> flattenedExpr = flattener.operandExprStack.back();
if (!expr.isPureAffine() &&
expr == getAffineExprFromFlatForm(flattenedExpr, numDims, numSymbols,
@@ -1573,7 +1584,10 @@ std::optional<int64_t> mlir::getBoundForAffineExpr(
}
// Flatten the expression.
SimpleAffineExprFlattener flattener(numDims, numSymbols);
- flattener.walkPostOrder(expr);
+ auto simpleResult = flattener.walkPostOrder(expr);
+ // has poison expression
+ if (failed(simpleResult))
+ return std::nullopt;
ArrayRef<int64_t> flattenedExpr = flattener.operandExprStack.back();
// TODO: Handle local variables. We can get hold of flattener.localExprs and
// get bound on the local expr recursively.
diff --git a/mlir/lib/IR/AffineMap.cpp b/mlir/lib/IR/AffineMap.cpp
index 93a8d048e0a61d5..e0293812277a276 100644
--- a/mlir/lib/IR/AffineMap.cpp
+++ b/mlir/lib/IR/AffineMap.cpp
@@ -8,6 +8,7 @@
#include "mlir/IR/AffineMap.h"
#include "AffineMapDetail.h"
+#include "mlir/Dialect/UB/IR/UBOps.h"
#include "mlir/IR/AffineExpr.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/BuiltinAttributes.h"
@@ -59,13 +60,34 @@ class AffineExprConstantFolder {
expr, [](int64_t lhs, int64_t rhs) { return lhs * rhs; });
case AffineExprKind::Mod:
return constantFoldBinExpr(
- expr, [](int64_t lhs, int64_t rhs) { return mod(lhs, rhs); });
+ expr,
+ [expr, this](int64_t lhs, int64_t rhs) -> std::optional<int64_t> {
+ if (rhs < 1) {
+ hasPoison_ = true;
+ return std::nullopt;
+ }
+ return mod(lhs, rhs);
+ });
case AffineExprKind::FloorDiv:
return constantFoldBinExpr(
- expr, [](int64_t lhs, int64_t rhs) { return floorDiv(lhs, rhs); });
+ expr,
+ [expr, this](int64_t lhs, int64_t rhs) -> std::optional<int64_t> {
+ if (rhs == 0) {
+ hasPoison_ = true;
+ return std::nullopt;
+ }
+ return floorDiv(lhs, rhs);
+ });
case AffineExprKind::CeilDiv:
return constantFoldBinExpr(
- expr, [](int64_t lhs, int64_t rhs) { return ceilDiv(lhs, rhs); });
+ expr,
+ [expr, this](int64_t lhs, int64_t rhs) -> std::optional<int64_t> {
+ if (rhs == 0) {
+ hasPoison_ = true;
+ return std::nullopt;
+ }
+ return ceilDiv(lhs, rhs);
+ });
case AffineExprKind::Constant:
return cast<AffineConstantExpr>(expr).getValue();
case AffineExprKind::DimId:
@@ -387,12 +409,12 @@ std::optional<unsigned> AffineMap::getResultPosition(AffineExpr input) const {
/// Folds the results of the application of an affine map on the provided
/// operands to a constant if possible. Returns false if the folding happens,
/// true otherwise.
-LogicalResult
-AffineMap::constantFold(ArrayRef<Attribute> operandConstants,
- SmallVectorImpl<Attribute> &results) const {
+LogicalResult AffineMap::constantFold(ArrayRef<Attribute> operandConstants,
+ SmallVectorImpl<Attribute> &results,
+ bool *hasPoison) const {
// Attempt partial folding.
SmallVector<int64_t, 2> integers;
- partialConstantFold(operandConstants, &integers);
+ partialConstantFold(operandConstants, &integers, hasPoison);
// If all expressions folded to a constant, populate results with attributes
// containing those constants.
@@ -406,9 +428,9 @@ AffineMap::constantFold(ArrayRef<Attribute> operandConstants,
return success();
}
-AffineMap
-AffineMap::partialConstantFold(ArrayRef<Attribute> operandConstants,
- SmallVectorImpl<int64_t> *results) const {
+AffineMap AffineMap::partialConstantFold(ArrayRef<Attribute> operandConstants,
+ SmallVectorImpl<int64_t> *results,
+ bool *hasPoison) const {
assert(getNumInputs() == operandConstants.size());
// Fold each of the result expressions.
@@ -418,6 +440,10 @@ AffineMap::partialConstantFold(ArrayRef<Attribute> operandConstants,
for (auto expr : getResults()) {
auto folded = exprFolder.constantFold(expr);
+ if (exprFolder.hasPoison() && hasPoison) {
+ *hasPoison = true;
+ return {};
+ }
// If did not fold to a constant, keep the original expression, and clear
// the integer results vector.
if (folded) {
diff --git a/mlir/test/Dialect/Affine/constant-fold.mlir b/mlir/test/Dialect/Affine/constant-fold.mlir
index cdce39855acdff4..5236b44ddfed967 100644
--- a/mlir/test/Dialect/Affine/constant-fold.mlir
+++ b/mlir/test/Dialect/Affine/constant-fold.mlir
@@ -60,3 +60,24 @@ func.func @affine_min(%variable: index) -> (index, index) {
// CHECK: return %[[r]], %[[C44]]
return %0, %1 : index, index
}
+
+// -----
+
+func.func @affine_apply_poison_division_zero() {
+ // This is just for mlir::context to load ub dailect
+ %ub = ub.poison : index
+ %c16 = arith.constant 16 : index
+ %0 = affine.apply affine_map<(d0)[s0] -> (d0 mod (s0 - s0))>(%c16)[%c16]
+ %1 = affine.apply affine_map<(d0)[s0] -> (d0 floordiv (s0 - s0))>(%c16)[%c16]
+ %2 = affine.apply affine_map<(d0)[s0] -> (d0 ceildiv (s0 - s0))>(%c16)[%c16]
+ %alloc = memref.alloc(%0, %1, %2) : memref<?x?x?xi1>
+ %3 = affine.load %alloc[%0, %1, %2] : memref<?x?x?xi1>
+ affine.store %3, %alloc[%0, %1, %2] : memref<?x?x?xi1>
+ return
+}
+
+// CHECK-NOT: affine.apply
+// CHECK: %[[poison:.*]] = ub.poison : index
+// CHECK-NEXT: %[[alloc:.*]] = memref.alloc(%[[poison]], %[[poison]], %[[poison]])
+// CHECK-NEXT: %[[load:.*]] = affine.load %[[alloc]][%[[poison]], %[[poison]], %[[poison]]] : memref<?x?x?xi1>
+// CHECK-NEXT: affine.store %[[load]], %alloc[%[[poison]], %[[poison]], %[[poison]]] : memref<?x?x?xi1>
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