cranelift: Remove brz and brnz (#5630)

Remove the brz and brnz instructions, as their behavior is now redundant with brif.

cranelift/docs/ir.md

@@ -49,8 +49,7 @@ function %average(i32, i32) -> f32 system_v {
 block1(v0: i32, v1: i32):
     v2 = f64const 0x0.0
     stack_store v2, ss0
-    brz v1, block5                  ; Handle count == 0.
-    jump block2
+    brif v1, block2, block5                  ; Handle count == 0.
 
 block2:
     v3 = iconst.i32 0
@@ -66,8 +65,7 @@ block3(v4: i32):
     stack_store v10, ss0
     v11 = iadd_imm v4, 1
     v12 = icmp ult v11, v1
-    brnz v12, block3(v11)           ; Loop backedge.
-    jump block4
+    brif v12, block3(v11), block4 ; Loop backedge.
 
 block4:
     v13 = stack_load.f64 ss0
@@ -414,8 +412,7 @@ function %gcd(i32 uext, i32 uext) -> i32 uext system_v {
     fn0 = %divmod(i32 uext, i32 uext) -> i32 uext, i32 uext
 
 block1(v0: i32, v1: i32):
-    brz v1, block3
-    jump block2
+    brif v1, block2, block3
 
 block2:
     v2, v3 = call fn0(v0, v1)

cranelift/docs/testing.md

@@ -169,12 +169,12 @@ command:
     function %nonsense(i32, i32) -> f32 {
     ; check: digraph %nonsense {
     ; regex: I=\binst\d+\b
-    ; check: label="{block0 | <$(BRZ=$I)>brz block2 | <$(JUMP=$I)>jump block1}"]
+    ; check: label="{block0 | <$(BRIF=$I)>brif v1, block1(v2), block2 }"]
 
     block0(v0: i32, v1: i32):
-        brz v1, block2            ; unordered: block0:$BRZ -> block2
         v2 = iconst.i32 0
-        jump block1(v2)           ; unordered: block0:$JUMP -> block1
+        brif v1, block1(v2), block2  ; unordered: block0:$BRIF -> block1
+                                     ; unordered: block0:$BRIF -> block2
 
     block1(v5: i32):
         return v0
@@ -195,10 +195,9 @@ Compute the dominator tree of each function and validate it against the
 
     function %test(i32) {
         block0(v0: i32):
-            jump block1     ; dominates: block1
+            jump block1              ; dominates: block1
         block1:
-            brz v0, block3  ; dominates: block3
-            jump block2     ; dominates: block2
+            brif v0, block2, block3  ; dominates: block2, block3
         block2:
             jump block3
         block3: