cranelift: Add support for bswap.i128 (#5186)

* fuzzgen: Request only one variable for bswap

This was included by accident. Bswap only has one input, instead of two.

* cranelift: Add `bswap.i128` support

Adds support only for x86, AArch64, S390X.

RISCV does not yet have bswap.

cranelift/codegen/src/isa/aarch64/lower.isle

@@ -1528,6 +1528,11 @@
 (rule (lower (has_type $I64 (bswap x)))
       (a64_rev64 $I64 x))
 
+(rule (lower (has_type $I128 (bswap x)))
+      (value_regs
+       (a64_rev64 $I64 (value_regs_get x 1))
+       (a64_rev64 $I64 (value_regs_get x 0))))
+
 ;;;; Rules for `bmask` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;; Bmask tests the value against zero, and uses `csetm` to assert the result.

cranelift/codegen/src/isa/s390x/lower.isle

@@ -1190,15 +1190,8 @@
 
 ;;;; Rules for `bswap` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(rule (lower (has_type $I16 (bswap x)))
-      (lshr_imm $I32 (bswap_reg $I32 x) 16))
-
-(rule (lower (has_type $I32 (bswap x)))
-      (bswap_reg $I32 x))
-
-(rule (lower (has_type $I64 (bswap x)))
-      (bswap_reg $I64 x))
-
+(rule (lower (has_type ty (bswap x)))
+      (bitrev_bytes ty x))
 
 ;;;; Rules for `clz` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 

cranelift/codegen/src/isa/x64/lower.isle

@@ -2060,6 +2060,11 @@
 (rule (lower (has_type $I64 (bswap src)))
       (x64_bswap $I64 src))
 
+(rule (lower (has_type $I128 (bswap src)))
+      (value_regs
+       (x64_bswap $I64 (value_regs_get_gpr src 1))
+       (x64_bswap $I64 (value_regs_get_gpr src 0))))
+
 ;; Rules for `is_null` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;; Null references are represented by the constant value `0`.