Don't require inlining for shape refinement (#2631)

Currently we require MLIR function inlining before refining shapes.
Refining shapes in order and following call operations (enforcing no
recursive calls) should allow for `refine(dynamic_export, static_args)
== static_export` to be true

docs/generated/stablehlo_passes.md

@@ -272,28 +272,47 @@ type of every argument to the `main` method being refined.
 
 _Refines shapes across a StableHLO program._
 
-Walks through a StableHLO program refining shapes within ops.
+  Walks through a StableHLO program refining shapes within ops.
 
-The flagship use case for this pass is specializing dynamically-shaped
-programs to static shapes. If a dynamically-shaped StableHLO program has the
-right structure, then updating its argument types from dynamic shapes to
-static shapes and running this pass will propagate static shapes across
-the program.
+  The flagship use case for this pass is specializing dynamically-shaped
+  programs to static shapes. If a dynamically-shaped StableHLO program has the
+  right structure, then updating its argument types from dynamic shapes to
+  static shapes and running this pass will propagate static shapes across
+  the program.
 
-This pass removes `custom_call @shape_refinement_operand_wrapper` by
-replacing uses of the result with the operand directly, and propagates
-static shapes throughout the program.
+  This pass removes `custom_call @shape_refinement_operand_wrapper` by
+  replacing uses of the result with the operand directly, and propagates
+  static shapes throughout the program.
 
-```
-%c = stablehlo.constant dense<16> : tensor<1xi64>
-%0 = stablehlo.custom_call @stablehlo.shape_refinement_operand_wrapper(%arg0, %c) {...}
-    : (tensor<16xf32>, tensor<1xi64>) -> tensor<?xf32>
-%1 = stablehlo.add %0, %0 : tensor<?xf32>
+  ```
+  %c = stablehlo.constant dense<16> : tensor<1xi64>
+  %0 = stablehlo.custom_call @stablehlo.shape_refinement_operand_wrapper(%arg0, %c) {...}
+      : (tensor<16xf32>, tensor<1xi64>) -> tensor<?xf32>
+  %1 = stablehlo.add %0, %0 : tensor<?xf32>
 
-==>
+  ==>
 
-%1 = stablehlo.add %arg0, %arg0 : tensor<16xf32>
-```
+  %1 = stablehlo.add %arg0, %arg0 : tensor<16xf32>
+  ```
+
+Modules valid for shape refinement must have the following properties:
+
+  * All the dynamic shapes depend only on the input shapes (no shape
+    dependency on the input array contents). We refer to the operations that
+    depend transitively only on the input shapes (e.g., as given by
+    `stablehlo.get_dimension_size`) or global constants like the resolved
+    values of symbolic integers (i.e. tensor<Axf32> : A = 5), as `dimension`
+    operations. All dimension values can be resolved to constants through
+    inter-procedural constant folding.
+  * Intermediate functions may take a number of token arguments (of type
+    !stablehlo.token) at the start of the argument list, followed by some
+    global constant arguments which are constant integer scalars, such as the
+    resolved values of symbolic integers (i.e. tensor<Axf32> : A = 5).
+  * Some intermediate functions may return computations on global constants,
+    i.e. `floordiv` on symint values. These functions are indicated by only
+    returning constant values after refinement. These functions are inlined.
+  * All calls to a single function resolve to the same argument shapes, and no
+    recursive / co-recursive function calls are made.
 ### `-vhlo-legalize-to-stablehlo`
 
 _Legalize VHLO to StableHLO._