Mass rename Ebb and relatives to Block (#1365)

* Manually rename BasicBlock to BlockPredecessor

BasicBlock is a pair of (Ebb, Inst) that is used to represent the
basic block subcomponent of an Ebb that is a predecessor to an Ebb.

Eventually we will be able to remove this struct, but for now it
makes sense to give it a non-conflicting name so that we can start
to transition Ebb to represent a basic block.

I have not updated any comments that refer to BasicBlock, as
eventually we will remove BlockPredecessor and replace with Block,
which is a basic block, so the comments will become correct.

* Manually rename SSABuilder block types to avoid conflict

SSABuilder has its own Block and BlockData types. These along with
associated identifier will cause conflicts in a later commit, so
they are renamed to be more verbose here.

* Automatically rename 'Ebb' to 'Block' in *.rs

* Automatically rename 'EBB' to 'block' in *.rs

* Automatically rename 'ebb' to 'block' in *.rs

* Automatically rename 'extended basic block' to 'basic block' in *.rs

* Automatically rename 'an basic block' to 'a basic block' in *.rs

* Manually update comment for `Block`

`Block`'s wikipedia article required an update.

* Automatically rename 'an `Block`' to 'a `Block`' in *.rs

* Automatically rename 'extended_basic_block' to 'basic_block' in *.rs

* Automatically rename 'ebb' to 'block' in *.clif

* Manually rename clif constant that contains 'ebb' as substring to avoid conflict

* Automatically rename filecheck uses of 'EBB' to 'BB'

'regex: EBB' -> 'regex: BB'
'$EBB' -> '$BB'

* Automatically rename 'EBB' 'Ebb' to 'block' in *.clif

* Automatically rename 'an block' to 'a block' in *.clif

* Fix broken testcase when function name length increases

Test function names are limited to 16 characters. This causes
the new longer name to be truncated and fail a filecheck test. An
outdated comment was also fixed.

cranelift/entity/src/lib.rs

@@ -104,7 +104,7 @@ macro_rules! entity_impl {
     };
 
     // Include basic `Display` impl using the given display prefix.
-    // Display an `Ebb` reference as "ebb12".
+    // Display a `Block` reference as "block12".
     ($entity:ident, $display_prefix:expr) => {
         entity_impl!($entity);
 

cranelift/entity/src/set.rs

@@ -216,7 +216,7 @@ mod tests {
 
     #[test]
     fn pop_unordered() {
-        let mut ebbs = [
+        let mut blocks = [
             E(0),
             E(1),
             E(6),
@@ -231,14 +231,14 @@ mod tests {
         ];
 
         let mut m = EntitySet::new();
-        for &ebb in &ebbs {
-            m.insert(ebb);
+        for &block in &blocks {
+            m.insert(block);
         }
         assert_eq!(m.len, 13);
-        ebbs.sort();
+        blocks.sort();
 
-        for &ebb in ebbs.iter().rev() {
-            assert_eq!(ebb, m.pop().unwrap());
+        for &block in blocks.iter().rev() {
+            assert_eq!(block, m.pop().unwrap());
         }
 
         assert!(m.is_empty());