Scop::makeIslAffFromStmtExpr: construct affine expression in parameter space

This is a further step towards allowing makeIslAffBoundsFromExpr
to only work in terms of parameters.
In particular, it removes a reliance on the names of set dimensions.

Since the parameter space is taken from the iteration domain,
the parameter space argument to Scop::makeIslAffFromStmtExpr
is no longer needed.

Author: Sven Verdoolaege

tc/core/polyhedral/codegen_llvm.cc

@@ -648,8 +648,7 @@ isl::ast_node collectIteratorMaps(
       scop.halide.statements.at(stmtId).as<Halide::Internal::Provide>();
   for (auto e : provide->args) {
     const auto& map = iteratorMap;
-    auto space = map.get_space().params();
-    auto aff = scop.makeIslAffFromStmtExpr(stmtId, space, e);
+    auto aff = scop.makeIslAffFromStmtExpr(stmtId, e);
     auto pulled = isl::pw_aff(aff).pullback(map);
     TC_CHECK_EQ(pulled.n_piece(), 1);
     subscripts.push_back(build.expr_from(pulled));

tc/core/polyhedral/cuda/codegen.h

@@ -136,8 +136,7 @@ struct CodegenStatementContext : CodegenContext {
   // of the variables does not correspond to a parameter or
   // an instance identifier of the statement.
   isl::aff makeIslAffFromExpr(const Halide::Expr& e) const {
-    auto space = iteratorMap().get_space().params();
-    return scop().makeIslAffFromStmtExpr(statementId(), space, e);
+    return scop().makeIslAffFromStmtExpr(statementId(), e);
   }
 
   isl::id astNodeId;

tc/core/polyhedral/scop.cc

@@ -503,18 +503,12 @@ const Halide::OutputImageParam& Scop::findArgument(isl::id id) const {
   return *halide.inputs.begin();
 }
 
-isl::aff Scop::makeIslAffFromStmtExpr(
-    isl::id stmtId,
-    isl::space paramSpace,
-    const Halide::Expr& e) const {
-  auto tuple = halide.domains.at(stmtId).tuple;
-  auto space = paramSpace.named_set_from_params_id(stmtId, tuple.size());
-  // Set the names of the set dimensions of "space" for use
-  // by halide2isl::makeIslAffFromExpr.
-  for (int i = 0; i < tuple.size(); ++i) {
-    space = space.set_dim_id(isl::dim_type::set, i, tuple.get_id(i));
-  }
-  return halide2isl::makeIslAffFromExpr(space, e);
+isl::aff Scop::makeIslAffFromStmtExpr(isl::id stmtId, const Halide::Expr& e)
+    const {
+  auto domain = halide.domains.at(stmtId);
+  auto aff = halide2isl::makeIslAffFromExpr(domain.paramSpace, e);
+  aff = aff.unbind_params_insert_domain(domain.tuple);
+  return aff;
 }
 
 } // namespace polyhedral

tc/core/polyhedral/scop.h

@@ -411,15 +411,11 @@ struct Scop {
   const Halide::OutputImageParam& findArgument(isl::id id) const;
 
   // Make an affine function from a Halide Expr that is defined
-  // over the instance set of the statement with identifier "stmtId" and
-  // with parameters specified by "paramSpace".  Return a
-  // null isl::aff if the expression is not affine.  Fail if any
+  // over the instance set of the statement with identifier "stmtId".
+  // Return a null isl::aff if the expression is not affine.  Fail if any
   // of the variables does not correspond to a parameter or
   // an instance identifier of the statement.
-  isl::aff makeIslAffFromStmtExpr(
-      isl::id stmtId,
-      isl::space paramSpace,
-      const Halide::Expr& e) const;
+  isl::aff makeIslAffFromStmtExpr(isl::id stmtId, const Halide::Expr& e) const;
 
   // Promote a tensor reference group to a storage of a given "kind",
   // inserting the copy