fuzzgen: Always generate reachable blocks (#5034)

* fuzzgen: Always reachable blocks

* fuzzgen: Rename BlockTerminator

* fuzzgen: Rename `finalize_block`

* fuzzgen: Use `cloned` instead of map clone

Thanks @jameysharp!

Co-authored-by: Jamey Sharp <jamey@minilop.net>

* fuzzgen: `rustfmt`

* fuzzgen: Document paramless targets

* fuzzgen:  Add `BlockTerminatorKind`

* fuzzen: Update BrTable/Switch comment

* fuzzgen: Minor cleanup

Co-authored-by: Jamey Sharp <jamey@minilop.net>

cranelift/codegen/src/ir/jumptable.rs

@@ -33,6 +33,10 @@ impl JumpTableData {
             table: Vec::with_capacity(capacity),
         }
     }
+    /// Create a new jump table with the provided blocks
+    pub fn with_blocks(table: Vec<Block>) -> Self {
+        Self { table }
+    }
 
     /// Get the number of table entries.
     pub fn len(&self) -> usize {

cranelift/fuzzgen/src/config.rs

@@ -16,10 +16,7 @@ pub struct Config {
     /// This value does not apply to block0 which takes the function params
     /// and is thus governed by `signature_params`
     pub block_signature_params: RangeInclusive<usize>,
-    /// Max number of jump tables generated per function
-    /// Note, the actual number of jump tables may be larger if the Switch interface
-    /// decides to insert more.
-    pub jump_tables_per_function: RangeInclusive<usize>,
+    /// Max number of jump tables entries to generate
     pub jump_table_entries: RangeInclusive<usize>,
 
     /// The Switch API specializes either individual blocks or contiguous ranges.
@@ -66,7 +63,6 @@ impl Default for Config {
             vars_per_function: 0..=16,
             blocks_per_function: 0..=16,
             block_signature_params: 0..=16,
-            jump_tables_per_function: 0..=4,
             jump_table_entries: 0..=16,
             switch_cases: 0..=64,
             // Ranges smaller than 2 don't make sense.