Adds a new drbbdup option max_case_encoding. When the value is small, we can avoid a 2nd scratch register for aarchxx, since we can fit all encodings in immediates inside compare instructions.
Adds a sanity check. Confirmed visually in the debug logs that the 2nd scratch is gone: Before:
--------------------------------------------------
after instrumentation:
TAG 0x0000ffff868340c0
+0 m4 @0x0000fffd428950e8 f900b781 str %x1 -> +0x0168(%x28)[8byte]
+4 m4 @0x0000fffd42894da0 d53b4200 mrs %nzcv -> %x0
+8 m4 @0x0000fffd42894cd8 f900af80 str %x0 -> +0x0158(%x28)[8byte]
+12 m4 @0x0000fffd42894c58 d28c1000 movz $0x6080 lsl $0x00 -> %x0
+16 m4 @0x0000fffd42894bd8 f2a85000 movk %x0 $0x4280 lsl $0x10 -> %x0
+20 m4 @0x0000fffd42894b10 f2dfffe0 movk %x0 $0xffff lsl $0x20 -> %x0
+24 m4 @0x0000fffd42894a48 f9400000 ldr (%x0)[8byte] -> %x0
+28 m4 @0x0000fffd42894e20 f9400000 <label>
+28 m4 @0x0000fffd42894980 f100041f subs %x0 $0x0000000000000001 lsl $0x0000000000000000 -> %xzr
+32 m4 @0x0000fffd42894900 54000001 b.ne @0x0000fffd42894fa0[8byte]
--------------------------------------------------After:
--------------------------------------------------
after instrumentation:
TAG 0x0000ffff9aedf0c0
+0 m4 @0x0000fffd56f400e8 d53b4200 mrs %nzcv -> %x0
+4 m4 @0x0000fffd56f3fda0 f900af80 str %x0 -> +0x0158(%x28)[8byte]
+8 m4 @0x0000fffd56f3fcd8 d2821000 movz $0x1080 lsl $0x00 -> %x0
+12 m4 @0x0000fffd56f3fc58 f2aadd60 movk %x0 $0x56eb lsl $0x10 -> %x0
+16 m4 @0x0000fffd56f3fbd8 f2dfffe0 movk %x0 $0xffff lsl $0x20 -> %x0
+20 m4 @0x0000fffd56f3fb10 f9400000 ldr (%x0)[8byte] -> %x0
+24 m4 @0x0000fffd56f3fe20 f9400000 <label>
+24 m4 @0x0000fffd56f3fa48 f100041f subs %x0 $0x0000000000000001 lsl $0x0000000000000000 -> %xzr
+28 m4 @0x0000fffd56f3f980 54000001 b.ne @0x0000fffd56f3ffa0[8byte]
--------------------------------------------------Issue: #4134 (closed)