Clang12 performance comparison

[chfast]

Comparing clang-12 against clang-11, without LTO. An improvement is visible. Hopefully, not because of the code layout.

fizzy/parse/blake2b_mean                                           +0.0103         +0.0103            25            25            25            25
fizzy/instantiate/blake2b_mean                                     -0.0129         -0.0129            31            31            31            31
fizzy/execute/blake2b/512_bytes_rounds_1_mean                      -0.0361         -0.0361            81            78            81            78
fizzy/execute/blake2b/512_bytes_rounds_16_mean                     -0.0603         -0.0603          1212          1139          1212          1139
fizzy/parse/ecpairing_mean                                         +0.0061         +0.0061          1450          1459          1450          1459
fizzy/instantiate/ecpairing_mean                                   +0.0073         +0.0073          1507          1518          1507          1518
fizzy/execute/ecpairing/onepoint_mean                              -0.0359         -0.0359        408026        393370        408002        393373
fizzy/parse/keccak256_mean                                         -0.0002         -0.0002            46            46            46            46
fizzy/instantiate/keccak256_mean                                   +0.0028         +0.0028            50            50            50            50
fizzy/execute/keccak256/512_bytes_rounds_1_mean                    -0.0854         -0.0854           102            93           102            93
fizzy/execute/keccak256/512_bytes_rounds_16_mean                   -0.0907         -0.0907          1487          1352          1487          1352
fizzy/parse/memset_mean                                            +0.0022         +0.0022             6             6             6             6
fizzy/instantiate/memset_mean                                      +0.0056         +0.0056            10            10            10            10
fizzy/execute/memset/256_bytes_mean                                -0.0452         -0.0452             7             6             7             6
fizzy/execute/memset/60000_bytes_mean                              -0.0460         -0.0460          1497          1428          1497          1428
fizzy/parse/mul256_opt0_mean                                       +0.0004         +0.0004             8             8             8             8
fizzy/instantiate/mul256_opt0_mean                                 +0.0019         +0.0019            12            12            12            12
fizzy/execute/mul256_opt0/input1_mean                              -0.0561         -0.0561            28            27            28            27
fizzy/parse/ramanujan_pi_mean                                      +0.0110         +0.0110            26            26            26            26
fizzy/instantiate/ramanujan_pi_mean                                +0.0137         +0.0137            30            30            30            30
fizzy/execute/ramanujan_pi/33_runs_mean                            -0.0159         -0.0159           110           108           110           108
fizzy/parse/sha1_mean                                              +0.0003         +0.0003            42            42            42            42
fizzy/instantiate/sha1_mean                                        +0.0033         +0.0033            45            46            45            46
fizzy/execute/sha1/512_bytes_rounds_1_mean                         -0.0025         -0.0025            88            88            88            88
fizzy/execute/sha1/512_bytes_rounds_16_mean                        -0.0080         -0.0080          1224          1215          1224          1215
fizzy/parse/sha256_mean                                            +0.0029         +0.0029            70            70            70            70
fizzy/instantiate/sha256_mean                                      +0.0064         +0.0064            74            75            74            75
fizzy/execute/sha256/512_bytes_rounds_1_mean                       -0.0026         -0.0026            81            81            81            81
fizzy/execute/sha256/512_bytes_rounds_16_mean                      -0.0026         -0.0026          1115          1112          1115          1112
fizzy/parse/taylor_pi_mean                                         +0.0015         +0.0015             3             3             3             3
fizzy/instantiate/taylor_pi_mean                                   +0.0045         +0.0045             6             6             6             6
fizzy/execute/taylor_pi/pi_1000000_runs_mean                       -0.0051         -0.0051         40718         40511         40718         40511
fizzy/parse/micro/eli_interpreter_mean                             -0.0065         -0.0065             4             4             4             4
fizzy/instantiate/micro/eli_interpreter_mean                       -0.0047         -0.0046             8             8             8             8
fizzy/execute/micro/eli_interpreter/exec105_mean                   -0.0580         -0.0579             4             4             4             4
fizzy/parse/micro/factorial_mean                                   +0.0091         +0.0092             1             1             1             1
fizzy/instantiate/micro/factorial_mean                             +0.0018         +0.0018             1             1             1             1
fizzy/execute/micro/factorial/20_mean                              -0.0611         -0.0611             1             1             1             1
fizzy/parse/micro/fibonacci_mean                                   +0.0189         +0.0189             1             1             1             1
fizzy/instantiate/micro/fibonacci_mean                             +0.0157         +0.0157             1             1             1             1
fizzy/execute/micro/fibonacci/24_mean                              -0.0024         -0.0024          5171          5159          5171          5159
fizzy/parse/micro/host_adler32_mean                                +0.0012         +0.0012             2             2             2             2
fizzy/instantiate/micro/host_adler32_mean                          -0.0148         -0.0148             4             4             4             4
fizzy/execute/micro/host_adler32/1_mean                            -0.0374         -0.0374             0             0             0             0
fizzy/execute/micro/host_adler32/1000_mean                         -0.0260         -0.0260            31            31            31            31
fizzy/parse/micro/icall_hash_mean                                  +0.0017         +0.0017             3             3             3             3
fizzy/instantiate/micro/icall_hash_mean                            -0.0014         -0.0014             7             7             7             7
fizzy/execute/micro/icall_hash/1000_steps_mean                     -0.0511         -0.0511            69            66            69            66
fizzy/parse/micro/spinner_mean                                     -0.0233         -0.0233             1             1             1             1
fizzy/instantiate/micro/spinner_mean                               -0.0056         -0.0057             1             1             1             1
fizzy/execute/micro/spinner/1_mean                                 -0.0854         -0.0855             0             0             0             0
fizzy/execute/micro/spinner/1000_mean                              -0.0276         -0.0276             9             9             9             9
fizzy/parse/stress/guido-fuzzer-find-1_mean                        +0.0022         +0.0022           146           146           146           146
fizzy/instantiate/stress/guido-fuzzer-find-1_mean                  -0.0017         -0.0017           176           175           176           175