Fix icount accounting.

Replace bitrev8 with revbit8.
 Fixes for set but not used warnings.
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Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20210726' into staging

Fix icount accounting.
Replace bitrev8 with revbit8.
Fixes for set but not used warnings.

# gpg: Signature made Mon 26 Jul 2021 22:45:37 BST
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth-gitlab/tags/pull-tcg-20210726:
  tests/unit: Remove unused variable from test_io
  linux-user/syscall: Remove unused variable from execve
  hw/pci-hist/pnv_phb4: Fix typo in pnv_phb4_ioda_write
  hw/ppc/spapr_events: Remove unused variable from check_exception
  hw/audio/adlib: Remove unused variable in adlib_callback
  net/checksum: Remove unused variable in net_checksum_add_iov
  util/selfmap: Discard mapping on error
  accel/tcg: Remove unused variable in cpu_exec
  nbd/server: Mark variable unused in nbd_negotiate_meta_queries
  bitops.h: revert db1ffc32dd ("qemu/bitops.h: add bitrev8 implementation")
  accel/tcg: Remove unnecessary check on icount_extra in cpu_loop_exec_tb()
  accel/tcg: Don't use CF_COUNT_MASK as the max value of icount_decr.u16.low

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

accel/tcg/cpu-exec.c

@@ -834,7 +834,7 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
     /* Ensure global icount has gone forward */
     icount_update(cpu);
     /* Refill decrementer and continue execution.  */
-    insns_left = MIN(CF_COUNT_MASK, cpu->icount_budget);
+    insns_left = MIN(0xffff, cpu->icount_budget);
     cpu_neg(cpu)->icount_decr.u16.low = insns_left;
     cpu->icount_extra = cpu->icount_budget - insns_left;
 
@@ -843,7 +843,9 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
      * execute we need to ensure we find/generate a TB with exactly
      * insns_left instructions in it.
      */
-    if (!cpu->icount_extra && insns_left > 0 && insns_left < tb->icount)  {
+    if (insns_left > 0 && insns_left < tb->icount)  {
+        assert(insns_left <= CF_COUNT_MASK);
+        assert(cpu->icount_extra == 0);
         cpu->cflags_next_tb = (tb->cflags & ~CF_COUNT_MASK) | insns_left;
     }
 #endif
@@ -853,7 +855,6 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
 
 int cpu_exec(CPUState *cpu)
 {
-    CPUClass *cc = CPU_GET_CLASS(cpu);
     int ret;
     SyncClocks sc = { 0 };
 
@@ -887,19 +888,14 @@ int cpu_exec(CPUState *cpu)
          * that we support, but is still unfixed in clang:
          *   https://bugs.llvm.org/show_bug.cgi?id=21183
          *
-         * Reload essential local variables here for those compilers.
+         * Reload an essential local variable here for those compilers.
          * Newer versions of gcc would complain about this code (-Wclobbered),
          * so we only perform the workaround for clang.
          */
         cpu = current_cpu;
-        cc = CPU_GET_CLASS(cpu);
 #else
-        /*
+        /* Non-buggy compilers preserve this; assert the correct value. */
-         * Non-buggy compilers preserve these locals; assert that
-         * they have the correct value.
-         */
         g_assert(cpu == current_cpu);
-        g_assert(cc == CPU_GET_CLASS(cpu));
 #endif
 
 #ifndef CONFIG_SOFTMMU

hw/audio/adlib.c

@@ -186,7 +186,7 @@ static int write_audio (AdlibState *s, int samples)
 static void adlib_callback (void *opaque, int free)
 {
     AdlibState *s = opaque;
-    int samples, net = 0, to_play, written;
+    int samples, to_play, written;
 
     samples = free >> SHIFT;
     if (!(s->active && s->enabled) || !samples) {
@@ -219,7 +219,6 @@ static void adlib_callback (void *opaque, int free)
         written = write_audio (s, samples);
 
         if (written) {
-            net += written;
             samples -= written;
             s->pos = (s->pos + written) % s->samples;
         }

hw/m68k/q800.c

@@ -334,7 +334,7 @@ static void q800_init(MachineState *machine)
     prom = memory_region_get_ram_ptr(dp8393x_prom);
     checksum = 0;
     for (i = 0; i < 6; i++) {
-        prom[i] = bitrev8(nd_table[0].macaddr.a[i]);
+        prom[i] = revbit8(nd_table[0].macaddr.a[i]);
         checksum ^= prom[i];
     }
     prom[7] = 0xff - checksum;

hw/pci-host/pnv_phb4.c

@@ -392,7 +392,7 @@ static void pnv_phb4_ioda_write(PnvPHB4 *phb, uint64_t val)
             v &= 0xffffffffffff0000ull;
             v |= 0x000000000000cfffull & val;
         }
-        *tptr = val;
+        *tptr = v;
         break;
     }
     case IODA3_TBL_MBT:

hw/ppc/spapr_events.c

@@ -934,7 +934,6 @@ static void check_exception(PowerPCCPU *cpu, SpaprMachineState *spapr,
                             uint32_t nret, target_ulong rets)
 {
     uint32_t mask, buf, len, event_len;
-    uint64_t xinfo;
     SpaprEventLogEntry *event;
     struct rtas_error_log header;
     int i;
@@ -944,13 +943,9 @@ static void check_exception(PowerPCCPU *cpu, SpaprMachineState *spapr,
         return;
     }
 
-    xinfo = rtas_ld(args, 1);
     mask = rtas_ld(args, 2);
     buf = rtas_ld(args, 4);
     len = rtas_ld(args, 5);
-    if (nargs == 7) {
-        xinfo |= (uint64_t)rtas_ld(args, 6) << 32;
-    }
 
     event = rtas_event_log_dequeue(spapr, mask);
     if (!event) {

include/qemu/bitops.h

@@ -618,26 +618,4 @@ static inline uint64_t half_unshuffle64(uint64_t x)
     return x;
 }
 
-/**
- * bitrev8:
- * @x: 8-bit value to be reversed
- *
- * Given an input value with bits::
- *
- *   ABCDEFGH
- *
- * return the value with its bits reversed from left to right::
- *
- *   HGFEDCBA
- *
- * Returns: the bit-reversed value.
- */
-static inline uint8_t bitrev8(uint8_t x)
-{
-    x = ((x >> 1) & 0x55) | ((x << 1) & 0xaa);
-    x = ((x >> 2) & 0x33) | ((x << 2) & 0xcc);
-    x = (x >> 4) | (x << 4) ;
-    return x;
-}
-
 #endif

linux-user/syscall.c

@@ -8364,7 +8364,6 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
             abi_ulong guest_envp;
             abi_ulong addr;
             char **q;
-            int total_size = 0;
 
             argc = 0;
             guest_argp = arg2;
@@ -8396,7 +8395,6 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
                     break;
                 if (!(*q = lock_user_string(addr)))
                     goto execve_efault;
-                total_size += strlen(*q) + 1;
             }
             *q = NULL;
 
@@ -8408,7 +8406,6 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
                     break;
                 if (!(*q = lock_user_string(addr)))
                     goto execve_efault;
-                total_size += strlen(*q) + 1;
             }
             *q = NULL;
 

nbd/server.c

@@ -973,7 +973,8 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
 {
     int ret;
     g_autofree char *export_name = NULL;
-    g_autofree bool *bitmaps = NULL;
+    /* Mark unused to work around https://bugs.llvm.org/show_bug.cgi?id=3888 */
+    g_autofree G_GNUC_UNUSED bool *bitmaps = NULL;
     NBDExportMetaContexts local_meta = {0};
     uint32_t nb_queries;
     size_t i;

net/checksum.c

@@ -186,12 +186,11 @@ uint32_t
 net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt,
                      uint32_t iov_off, uint32_t size, uint32_t csum_offset)
 {
-    size_t iovec_off, buf_off;
+    size_t iovec_off;
     unsigned int i;
     uint32_t res = 0;
 
     iovec_off = 0;
-    buf_off = 0;
     for (i = 0; i < iov_cnt && size; i++) {
         if (iov_off < (iovec_off + iov[i].iov_len)) {
             size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
@@ -200,7 +199,6 @@ net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt,
             res += net_checksum_add_cont(len, chunk_buf, csum_offset);
             csum_offset += len;
 
-            buf_off += len;
             iov_off += len;
             size -= len;
         }

tests/unit/test-iov.c

@@ -158,7 +158,7 @@ static void test_io(void)
 
     int sv[2];
     int r;
-    unsigned i, j, k, s, t;
+    unsigned i, j, k, s;
     fd_set fds;
     unsigned niov;
     struct iovec *iov, *siov;
@@ -182,7 +182,6 @@ static void test_io(void)
 
     FD_ZERO(&fds);
 
-    t = 0;
     if (fork() == 0) {
        /* writer */
 
@@ -201,7 +200,6 @@ static void test_io(void)
                    g_assert(memcmp(iov, siov, sizeof(*iov)*niov) == 0);
                    if (r >= 0) {
                        k += r;
-                       t += r;
                        usleep(g_test_rand_int_range(0, 30));
                    } else if (errno == EAGAIN) {
                        select(sv[1]+1, NULL, &fds, NULL, NULL);
@@ -238,7 +236,6 @@ static void test_io(void)
                    g_assert(memcmp(iov, siov, sizeof(*iov)*niov) == 0);
                    if (r > 0) {
                        k += r;
-                       t += r;
                    } else if (!r) {
                        if (s) {
                            break;

util/selfmap.c

@@ -23,21 +23,22 @@ GSList *read_self_maps(void)
             gchar **fields = g_strsplit(lines[i], " ", 6);
             if (g_strv_length(fields) > 4) {
                 MapInfo *e = g_new0(MapInfo, 1);
-                int errors;
+                int errors = 0;
                 const char *end;
 
-                errors  = qemu_strtoul(fields[0], &end, 16, &e->start);
+                errors |= qemu_strtoul(fields[0], &end, 16, &e->start);
-                errors += qemu_strtoul(end + 1, NULL, 16, &e->end);
+                errors |= qemu_strtoul(end + 1, NULL, 16, &e->end);
 
                 e->is_read  = fields[1][0] == 'r';
                 e->is_write = fields[1][1] == 'w';
                 e->is_exec  = fields[1][2] == 'x';
                 e->is_priv  = fields[1][3] == 'p';
 
-                errors += qemu_strtoul(fields[2], NULL, 16, &e->offset);
+                errors |= qemu_strtoul(fields[2], NULL, 16, &e->offset);
                 e->dev = g_strdup(fields[3]);
-                errors += qemu_strtou64(fields[4], NULL, 10, &e->inode);
+                errors |= qemu_strtou64(fields[4], NULL, 10, &e->inode);
 
+                if (!errors) {
                     /*
                      * The last field may have leading spaces which we
                      * need to strip.
@@ -46,6 +47,10 @@ GSList *read_self_maps(void)
                         e->path = g_strdup(g_strchug(fields[5]));
                     }
                     map_info = g_slist_prepend(map_info, e);
+                } else {
+                    g_free(e->dev);
+                    g_free(e);
+                }
             }
 
             g_strfreev(fields);