Remove trapif and trapff (#5162)

This branch removes the trapif and trapff instructions, in favor of using an explicit comparison and trapnz. This moves us closer to removing iflags and fflags, but introduces the need to implement instructions like iadd_cout in the x64 and aarch64 backends.

cranelift/filetests/filetests/isa/aarch64/traps.clif

@@ -11,13 +11,12 @@ block0:
 
 function %trap_iadd_ifcout(i64, i64) {
 block0(v0: i64, v1: i64):
-  v2, v3 = iadd_ifcout v0, v1
-  trapif ult v3, user0
+  v2 = uadd_overflow_trap v0, v1, user0
   return
 }
 
 ; block0:
 ;   adds x3, x0, x1
-;   b.hs 8 ; udf
+;   b.lo 8 ; udf
 ;   ret
 

cranelift/filetests/filetests/isa/riscv64/traps.clif

@@ -13,16 +13,19 @@ block0:
 function %g(i64) {
 block0(v0: i64):
   v1 = iconst.i64 42
-  v2 = ifcmp v0, v1
-  trapif eq v2, user0
+  v2 = icmp eq v0, v1
+  trapnz v2, user0
   return
 }
 
 ; block0:
 ;   li t2,42
-;   eq a1,a0,t2##ty=i64
-;   trap_if a1,user0
+;   ne a1,a0,t2##ty=i64
+;   bne a1,zero,taken(label1),not_taken(label2)
+; block1:
 ;   ret
+; block2:
+;   udf##trap_code=user0
 
 function %h() {
 block0:

cranelift/filetests/filetests/isa/x64/traps.clif

@@ -14,8 +14,7 @@ block0:
 
 function %trap_iadd_ifcout(i64, i64) {
 block0(v0: i64, v1: i64):
-  v2, v3 = iadd_ifcout v0, v1
-  trapif ult v3, user0
+  v2 = uadd_overflow_trap v0, v1, user0
   return
 }