Mind all-zeroes IPv6 netmask tetras in gen_hostop6().

Produce as few comparison blocks as possible: skip all zero 32-bit
parts, generate one always-true comparison only if it is the only
comparison block.

Now the unoptimized filter program for "ip6 dst net ::/0" has only one
always-true comparison, longer IPv6 netmasks have none and are the same
as the optimized version.

diff --git a/gencode.c b/gencode.c
index 74780cdc085215e0e80baa9522d31d0c7b858f0f..0f6866f84acf403602868c2d1eb6c0b58ab01bcf 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -4472,14 +4472,19 @@ gen_hostop6(compiler_state_t *cstate, struct in6_addr *addr,
        /* this order is important */
        memcpy(a, addr, sizeof(a));
        memcpy(m, mask, sizeof(m));
-       b1 = gen_mcmp(cstate, OR_LINKPL, offset + 12, BPF_W, ntohl(a[3]), ntohl(m[3]));
-       b0 = gen_mcmp(cstate, OR_LINKPL, offset + 8, BPF_W, ntohl(a[2]), ntohl(m[2]));
-       gen_and(b0, b1);
-       b0 = gen_mcmp(cstate, OR_LINKPL, offset + 4, BPF_W, ntohl(a[1]), ntohl(m[1]));
-       gen_and(b0, b1);
-       b0 = gen_mcmp(cstate, OR_LINKPL, offset + 0, BPF_W, ntohl(a[0]), ntohl(m[0]));
-       gen_and(b0, b1);
-       return b1;
+       b1 = NULL;
+       for (int i = 3; i >= 0; i--) {
+               // Same as the Q_IP case in gen_host().
+               if (m[i] == 0 && a[i] == 0)
+                       continue;
+               b0 = gen_mcmp(cstate, OR_LINKPL, offset + 4 * i, BPF_W,
+                   ntohl(a[i]), ntohl(m[i]));
+               if (b1)
+                       gen_and(b0, b1);
+               else
+                       b1 = b0;
+       }
+       return b1 ? b1 : gen_true(cstate);
 }
 #endif
 

diff --git a/testprogs/TESTrun b/testprogs/TESTrun
index 12704fc151b71d209d99f616c1836229fabe8a95..d671042f699b6cd23b9480e6693bf6fc637f7446 100755 (executable)
--- a/testprogs/TESTrun
+++ b/testprogs/TESTrun
@@ -11625,17 +11625,11 @@ my @accept_blocks = (
                unopt => '
                        (000) ldb      [0]
                        (001) and      #0xf0
-                       (002) jeq      #0x60            jt 3    jf 12
+                       (002) jeq      #0x60            jt 3    jf 6
                        (003) ld       #0x0
-                       (004) jeq      #0x0             jt 5    jf 12
-                       (005) ld       #0x0
-                       (006) jeq      #0x0             jt 7    jf 12
-                       (007) ld       #0x0
-                       (008) jeq      #0x0             jt 9    jf 12
-                       (009) ld       #0x0
-                       (010) jeq      #0x0             jt 11   jf 12
-                       (011) ret      #262144
-                       (012) ret      #0
+                       (004) jeq      #0x0             jt 5    jf 6
+                       (005) ret      #262144
+                       (006) ret      #0
                        ',
        }, # ip6_dst_net_0
        {
@@ -11643,7 +11637,7 @@ my @accept_blocks = (
                skip => skip_config_undef ('INET6'),
                DLT => 'RAW',
                aliases => ['ip6 dst net ff00::/8'],
-               opt => '
+               unopt => '
                        (000) ldb      [0]
                        (001) and      #0xf0
                        (002) jeq      #0x60            jt 3    jf 7
@@ -11653,29 +11647,13 @@ my @accept_blocks = (
                        (006) ret      #262144
                        (007) ret      #0
                        ',
-               unopt => '
-                       (000) ldb      [0]
-                       (001) and      #0xf0
-                       (002) jeq      #0x60            jt 3    jf 13
-                       (003) ld       [24]
-                       (004) and      #0xff000000
-                       (005) jeq      #0xff000000      jt 6    jf 13
-                       (006) ld       #0x0
-                       (007) jeq      #0x0             jt 8    jf 13
-                       (008) ld       #0x0
-                       (009) jeq      #0x0             jt 10   jf 13
-                       (010) ld       #0x0
-                       (011) jeq      #0x0             jt 12   jf 13
-                       (012) ret      #262144
-                       (013) ret      #0
-                       ',
        }, # ip6_dst_net_8
        {
                name => 'ip6_dst_net_40',
                skip => skip_config_undef ('INET6'),
                DLT => 'RAW',
                aliases => ['ip6 dst net ff11:2233:4400::/40'],
-               opt => '
+               unopt => '
                        (000) ldb      [0]
                        (001) and      #0xf0
                        (002) jeq      #0x60            jt 3    jf 9
@@ -11687,29 +11665,13 @@ my @accept_blocks = (
                        (008) ret      #262144
                        (009) ret      #0
                        ',
-               unopt => '
-                       (000) ldb      [0]
-                       (001) and      #0xf0
-                       (002) jeq      #0x60            jt 3    jf 13
-                       (003) ld       [24]
-                       (004) jeq      #0xff112233      jt 5    jf 13
-                       (005) ld       [28]
-                       (006) and      #0xff000000
-                       (007) jeq      #0x44000000      jt 8    jf 13
-                       (008) ld       #0x0
-                       (009) jeq      #0x0             jt 10   jf 13
-                       (010) ld       #0x0
-                       (011) jeq      #0x0             jt 12   jf 13
-                       (012) ret      #262144
-                       (013) ret      #0
-                       ',
        }, # ip6_dst_net_40
        {
                name => 'ip6_dst_net_80',
                skip => skip_config_undef ('INET6'),
                DLT => 'RAW',
                aliases => ['ip6 dst net ff11:2233:4455:6677:8899::/80'],
-               opt => '
+               unopt => '
                        (000) ldb      [0]
                        (001) and      #0xf0
                        (002) jeq      #0x60            jt 3    jf 11
@@ -11723,22 +11685,6 @@ my @accept_blocks = (
                        (010) ret      #262144
                        (011) ret      #0
                        ',
-               unopt => '
-                       (000) ldb      [0]
-                       (001) and      #0xf0
-                       (002) jeq      #0x60            jt 3    jf 13
-                       (003) ld       [24]
-                       (004) jeq      #0xff112233      jt 5    jf 13
-                       (005) ld       [28]
-                       (006) jeq      #0x44556677      jt 7    jf 13
-                       (007) ld       [32]
-                       (008) and      #0xffff0000
-                       (009) jeq      #0x88990000      jt 10   jf 13
-                       (010) ld       #0x0
-                       (011) jeq      #0x0             jt 12   jf 13
-                       (012) ret      #262144
-                       (013) ret      #0
-                       ',
        }, # ip6_dst_net_80
        {
                name => 'ip6_dst_net_120',