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outdated comment was also fixed.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/filetests/filetests/safepoint/basic.clif

@@ -3,69 +3,69 @@ set enable_safepoints=true
 target x86_64
 
 function %test(i32, r64, r64) -> r64 {
-    ebb0(v0: i32, v1:r64, v2:r64):
-        jump ebb1(v0)
-    ebb1(v3: i32):
+    block0(v0: i32, v1:r64, v2:r64):
+        jump block1(v0)
+    block1(v3: i32):
         v4 = irsub_imm v3, 1
-        jump ebb2(v4)
-    ebb2(v5: i32):
+        jump block2(v4)
+    block2(v5: i32):
         resumable_trap interrupt
-        brz v5, ebb1(v5)
-        jump ebb3
-    ebb3:
+        brz v5, block1(v5)
+        jump block3
+    block3:
         v6 = null.r64
         v7 = is_null v6
-        brnz v7, ebb2(v0)
-        jump ebb4
-    ebb4:
-        brnz v0, ebb5
-        jump ebb6
-    ebb5:
+        brnz v7, block2(v0)
+        jump block4
+    block4:
+        brnz v0, block5
+        jump block6
+    block5:
         return v1
-    ebb6:
+    block6:
         return v2
 }
 
 ; sameln: function %test(i32 [%rdi], r64 [%rsi], r64 [%rdx]) -> r64 [%rax] fast {
-; nextln: ebb0(v0: i32 [%rdi], v1: r64 [%rsi], v2: r64 [%rdx]):
+; nextln: block0(v0: i32 [%rdi], v1: r64 [%rsi], v2: r64 [%rdx]):
 ; nextln:   v10 = copy v0
-; nextln:   jump ebb1(v10)
+; nextln:   jump block1(v10)
 ; nextln: 
-; nextln: ebb7:
+; nextln: block7:
 ; nextln:   regmove.i32 v5, %rcx -> %rax
-; nextln:   jump ebb1(v5)
+; nextln:   jump block1(v5)
 ; nextln: 
-; nextln: ebb1(v3: i32 [%rax]):
+; nextln: block1(v3: i32 [%rax]):
 ; nextln:   v8 = iconst.i32 1
 ; nextln:   v4 = isub v8, v3
-; nextln:   jump ebb2(v4)
+; nextln:   jump block2(v4)
 ; nextln: 
-; nextln: ebb8:
+; nextln: block8:
 ; nextln:   v9 = copy.i32 v0
 ; nextln:   regmove v9, %rax -> %rcx
-; nextln:   jump ebb2(v9)
+; nextln:   jump block2(v9)
 ; nextln: 
-; nextln: ebb2(v5: i32 [%rcx]):
+; nextln: block2(v5: i32 [%rcx]):
 ; nextln:   safepoint v1, v2
 ; nextln:   resumable_trap interrupt
-; nextln:   brz v5, ebb7
-; nextln:   jump ebb3
+; nextln:   brz v5, block7
+; nextln:   jump block3
 ; nextln: 
-; nextln: ebb3:
+; nextln: block3:
 ; nextln:   v6 = null.r64 
 ; nextln:   v7 = is_null v6
-; nextln:   brnz v7, ebb8
-; nextln:   jump ebb4
+; nextln:   brnz v7, block8
+; nextln:   jump block4
 ; nextln: 
-; nextln: ebb4:
-; nextln:   brnz.i32 v0, ebb5
-; nextln:   jump ebb6
+; nextln: block4:
+; nextln:   brnz.i32 v0, block5
+; nextln:   jump block6
 ; nextln: 
-; nextln: ebb5:
+; nextln: block5:
 ; nextln:   regmove.r64 v1, %rsi -> %rax
 ; nextln:   return v1
 ; nextln: 
-; nextln: ebb6:
+; nextln: block6:
 ; nextln:   regmove.r64 v2, %rdx -> %rax
 ; nextln:   return v2
 ; nextln: }

cranelift/filetests/filetests/safepoint/call.clif

@@ -7,15 +7,15 @@ function %direct() -> r64 {
     fn1 = %one() -> r64
     fn2 = %two() -> i32, r64
 
-ebb0:
+block0:
     call fn0()
     v1 = call fn1()
     v2, v3 = call fn2()
-    brz v2, ebb2
-    jump ebb1
-ebb1:
+    brz v2, block2
+    jump block1
+block1:
     return v1
-ebb2:
+block2:
     v4 = call fn1()
     return v3
 }
@@ -30,7 +30,7 @@ ebb2:
 ; nextln: fn1 = %one sig1
 ; nextln: fn2 = %two sig2
 ; nextln: 
-; nextln: ebb0:
+; nextln: block0:
 ; nextln:   v5 = func_addr.i64 fn0
 ; nextln:   call_indirect sig0, v5()
 ; nextln:   v6 = func_addr.i64 fn1
@@ -40,15 +40,15 @@ ebb2:
 ; nextln:   safepoint v1
 ; nextln:   v2, v10 = call_indirect sig2, v7()
 ; nextln:   v3 = spill v10
-; nextln:   brz v2, ebb2
-; nextln:   jump ebb1
+; nextln:   brz v2, block2
+; nextln:   jump block1
 ; nextln: 
-; nextln: ebb1:
+; nextln: block1:
 ; nextln:   v11 = fill.r64 v1
 ; nextln:   regmove v11, %r15 -> %rax
 ; nextln:   return v11
 ; nextln: 
-; nextln: ebb2:
+; nextln: block2:
 ; nextln:   v8 = func_addr.i64 fn1
 ; nextln:   safepoint v3
 ; nextln:   v4 = call_indirect sig1, v8()