EDSC: support multi-expression loop bounds

MLIR supports 'for' loops with lower(upper) bound defined by taking a
maximum(minimum) of a list of expressions, but does not have first-class affine
constructs for the maximum(minimum).  All these expressions must have affine
provenance, similarly to a single-expression bound.  Add support for
constructing such loops using EDSC.  The expression factory function is called
`edsc::MaxMinFor` to (1) highlight that the maximum(minimum) operation is
applied to the lower(upper) bound expressions and (2) differentiate it from a
`edsc::For` that creates multiple perfectly nested loops (and should arguably
be called `edsc::ForNest`).

PiperOrigin-RevId: 234785996

1 files changed, 11 insertions, 4 deletions

diff --git a/mlir/include/mlir-c/Core.h b/mlir/include/mlir-c/Core.h
index c8967860f47..8505cdc0ae6 100644
--- a/mlir/include/mlir-c/Core.h
+++ b/mlir/include/mlir-c/Core.h
@@ -227,17 +227,24 @@ edsc_stmt_t Return(edsc_expr_list_t values);
 /// given list of statements.  Block arguments are not currently supported.
 edsc_block_t Block(edsc_stmt_list_t enclosedStmts);
 
-/// Returns an opaque statement for an mlir::ForInst with `enclosedStmts` nested
-/// below it.
+/// Returns an opaque statement for an mlir::AffineForOp with `enclosedStmts`
+/// nested below it.
 edsc_stmt_t For(edsc_expr_t iv, edsc_expr_t lb, edsc_expr_t ub,
                 edsc_expr_t step, edsc_stmt_list_t enclosedStmts);
 
-/// Returns an opaque statement for a perfectly nested set of mlir::ForInst with
-/// `enclosedStmts` nested below it.
+/// Returns an opaque statement for a perfectly nested set of mlir::AffineForOp
+/// with `enclosedStmts` nested below it.
 edsc_stmt_t ForNest(edsc_expr_list_t iv, edsc_expr_list_t lb,
                     edsc_expr_list_t ub, edsc_expr_list_t step,
                     edsc_stmt_list_t enclosedStmts);
 
+/// Returns an opaque statement for an mlir::AffineForOp with the lower bound
+/// `max(lbs)` and the upper bound `min(ubs)`, and with `enclosedStmts` nested
+/// below it.
+edsc_stmt_t MaxMinFor(edsc_expr_t iv, edsc_expr_list_t lbs,
+                      edsc_expr_list_t ubs, edsc_expr_t step,
+                      edsc_stmt_list_t enclosedStmts);
+
 /// Returns an opaque expression for the corresponding Binary operation.
 edsc_expr_t Add(edsc_expr_t e1, edsc_expr_t e2);
 edsc_expr_t Sub(edsc_expr_t e1, edsc_expr_t e2);