[v4,03/19] tcg: Introduce TYPE_CONST temporaries

Message ID 20200508182616.18318-4-richard.henderson@linaro.org
State New
Headers show
Series
  • tcg: Better handling of constants
Related show

Commit Message

Richard Henderson May 8, 2020, 6:26 p.m.
These will hold a single constant for the duration of the TB.
They are hashed, so that each value has one temp across the TB.

Not used yet, this is all infrastructure.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 include/tcg/tcg.h |  27 +++++++-
 tcg/optimize.c    |  13 +++-
 tcg/tcg-op-vec.c  |  17 +++++
 tcg/tcg.c         | 170 ++++++++++++++++++++++++++++++++++------------
 4 files changed, 182 insertions(+), 45 deletions(-)

-- 
2.20.1

Patch

diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h
index 0d09ea7822..57d6b0216c 100644
--- a/include/tcg/tcg.h
+++ b/include/tcg/tcg.h
@@ -492,6 +492,8 @@  typedef enum TCGTempKind {
     TEMP_GLOBAL,
     /* Temp is in a fixed register. */
     TEMP_FIXED,
+    /* Temp is a fixed constant. */
+    TEMP_CONST,
 } TCGTempKind;
 
 typedef struct TCGTemp {
@@ -667,6 +669,7 @@  struct TCGContext {
     QSIMPLEQ_HEAD(, TCGOp) plugin_ops;
 #endif
 
+    GHashTable *const_table[TCG_TYPE_COUNT];
     TCGTempSet free_temps[TCG_TYPE_COUNT * 2];
     TCGTemp temps[TCG_MAX_TEMPS]; /* globals first, temps after */
 
@@ -683,7 +686,7 @@  struct TCGContext {
 
 static inline bool temp_readonly(TCGTemp *ts)
 {
-    return ts->kind == TEMP_FIXED;
+    return ts->kind >= TEMP_FIXED;
 }
 
 extern TCGContext tcg_init_ctx;
@@ -1041,6 +1044,7 @@  TCGOp *tcg_op_insert_after(TCGContext *s, TCGOp *op, TCGOpcode opc);
 
 void tcg_optimize(TCGContext *s);
 
+/* Allocate a new temporary and initialize it with a constant. */
 TCGv_i32 tcg_const_i32(int32_t val);
 TCGv_i64 tcg_const_i64(int64_t val);
 TCGv_i32 tcg_const_local_i32(int32_t val);
@@ -1050,6 +1054,27 @@  TCGv_vec tcg_const_ones_vec(TCGType);
 TCGv_vec tcg_const_zeros_vec_matching(TCGv_vec);
 TCGv_vec tcg_const_ones_vec_matching(TCGv_vec);
 
+/*
+ * Locate or create a read-only temporary that is a constant.
+ * This kind of temporary need not and should not be freed.
+ */
+TCGTemp *tcg_constant_internal(TCGType type, tcg_target_long val);
+
+static inline TCGv_i32 tcg_constant_i32(int32_t val)
+{
+    return temp_tcgv_i32(tcg_constant_internal(TCG_TYPE_I32, val));
+}
+
+static inline TCGv_i64 tcg_constant_i64(int64_t val)
+{
+    if (TCG_TARGET_REG_BITS == 32) {
+        qemu_build_not_reached();
+    }
+    return temp_tcgv_i64(tcg_constant_internal(TCG_TYPE_I64, val));
+}
+
+TCGv_vec tcg_constant_vec(TCGType type, unsigned vece, int64_t val);
+
 #if UINTPTR_MAX == UINT32_MAX
 # define tcg_const_ptr(x)        ((TCGv_ptr)tcg_const_i32((intptr_t)(x)))
 # define tcg_const_local_ptr(x)  ((TCGv_ptr)tcg_const_local_i32((intptr_t)(x)))
diff --git a/tcg/optimize.c b/tcg/optimize.c
index afb4a9a5a9..8f3bd99ff4 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -99,8 +99,17 @@  static void init_ts_info(struct tcg_temp_info *infos,
         ts->state_ptr = ti;
         ti->next_copy = ts;
         ti->prev_copy = ts;
-        ti->is_const = false;
-        ti->mask = -1;
+        if (ts->kind == TEMP_CONST) {
+            ti->is_const = true;
+            ti->val = ti->mask = ts->val;
+            if (TCG_TARGET_REG_BITS > 32 && ts->type == TCG_TYPE_I32) {
+                /* High bits of a 32-bit quantity are garbage.  */
+                ti->mask |= ~0xffffffffull;
+            }
+        } else {
+            ti->is_const = false;
+            ti->mask = -1;
+        }
         set_bit(idx, temps_used->l);
     }
 }
diff --git a/tcg/tcg-op-vec.c b/tcg/tcg-op-vec.c
index f784517d84..43101defe4 100644
--- a/tcg/tcg-op-vec.c
+++ b/tcg/tcg-op-vec.c
@@ -209,6 +209,23 @@  static void vec_gen_op3(TCGOpcode opc, unsigned vece,
     vec_gen_3(opc, type, vece, temp_arg(rt), temp_arg(at), temp_arg(bt));
 }
 
+TCGv_vec tcg_constant_vec(TCGType type, unsigned vece, int64_t val)
+{
+    val = dup_const(vece, val);
+
+    /*
+     * For MO_64 constants that can't be represented in tcg_target_long,
+     * we must use INDEX_op_dup2_vec, which requires a non-const temporary.
+     */
+    if (TCG_TARGET_REG_BITS == 32 &&
+        val != deposit64(val, 32, 32, val) &&
+        val != (uint64_t)(int32_t)val) {
+        g_assert_not_reached();
+    }
+
+    return temp_tcgv_vec(tcg_constant_internal(type, val));
+}
+
 void tcg_gen_mov_vec(TCGv_vec r, TCGv_vec a)
 {
     if (r != a) {
diff --git a/tcg/tcg.c b/tcg/tcg.c
index a529166026..94f7898317 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1127,6 +1127,7 @@  void tcg_func_start(TCGContext *s)
 
     /* No temps have been previously allocated for size or locality.  */
     memset(s->free_temps, 0, sizeof(s->free_temps));
+    memset(s->const_table, 0, sizeof(s->const_table));
 
     s->nb_ops = 0;
     s->nb_labels = 0;
@@ -1199,13 +1200,19 @@  TCGTemp *tcg_global_mem_new_internal(TCGType type, TCGv_ptr base,
     bigendian = 1;
 #endif
 
-    if (base_ts->kind != TEMP_FIXED) {
+    switch (base_ts->kind) {
+    case TEMP_FIXED:
+        break;
+    case TEMP_GLOBAL:
         /* We do not support double-indirect registers.  */
         tcg_debug_assert(!base_ts->indirect_reg);
         base_ts->indirect_base = 1;
         s->nb_indirects += (TCG_TARGET_REG_BITS == 32 && type == TCG_TYPE_I64
                             ? 2 : 1);
         indirect_reg = 1;
+        break;
+    default:
+        g_assert_not_reached();
     }
 
     if (TCG_TARGET_REG_BITS == 32 && type == TCG_TYPE_I64) {
@@ -1346,6 +1353,37 @@  void tcg_temp_free_internal(TCGTemp *ts)
     set_bit(idx, s->free_temps[k].l);
 }
 
+TCGTemp *tcg_constant_internal(TCGType type, tcg_target_long val)
+{
+    TCGContext *s = tcg_ctx;
+    GHashTable *h = s->const_table[type];
+    TCGTemp *ts;
+
+    if (h == NULL) {
+        if (sizeof(tcg_target_long) == sizeof(gint64)) {
+            h = g_hash_table_new(g_int64_hash, g_int64_equal);
+        } else if (sizeof(tcg_target_long) == sizeof(gint)) {
+            h = g_hash_table_new(g_int_hash, g_int_equal);
+        } else {
+            qemu_build_not_reached();
+        }
+        s->const_table[type] = h;
+    }
+
+    ts = g_hash_table_lookup(h, &val);
+    if (ts == NULL) {
+        ts = tcg_temp_alloc(s);
+        ts->base_type = type;
+        ts->type = type;
+        ts->kind = TEMP_CONST;
+        ts->temp_allocated = 1;
+        ts->val = val;
+        g_hash_table_insert(h, &ts->val, ts);
+    }
+
+    return ts;
+}
+
 TCGv_i32 tcg_const_i32(int32_t val)
 {
     TCGv_i32 t0;
@@ -1878,6 +1916,9 @@  static void tcg_reg_alloc_start(TCGContext *s)
         TCGTempVal val = TEMP_VAL_MEM;
 
         switch (ts->kind) {
+        case TEMP_CONST:
+            val = TEMP_VAL_CONST;
+            break;
         case TEMP_FIXED:
             val = TEMP_VAL_REG;
             break;
@@ -1914,6 +1955,26 @@  static char *tcg_get_arg_str_ptr(TCGContext *s, char *buf, int buf_size,
     case TEMP_NORMAL:
         snprintf(buf, buf_size, "tmp%d", idx - s->nb_globals);
         break;
+    case TEMP_CONST:
+        switch (ts->type) {
+        case TCG_TYPE_I32:
+            snprintf(buf, buf_size, "$0x%x", (int32_t)ts->val);
+            break;
+#if TCG_TARGET_REG_BITS > 32
+        case TCG_TYPE_I64:
+            snprintf(buf, buf_size, "$0x%" TCG_PRIlx, ts->val);
+            break;
+#endif
+        case TCG_TYPE_V64:
+        case TCG_TYPE_V128:
+        case TCG_TYPE_V256:
+            snprintf(buf, buf_size, "v%d$0x%" TCG_PRIlx,
+                     64 << (ts->type - TCG_TYPE_V64), ts->val);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+        break;
     }
     return buf;
 }
@@ -2520,6 +2581,7 @@  static void la_bb_end(TCGContext *s, int ng, int nt)
             state = TS_DEAD | TS_MEM;
             break;
         case TEMP_NORMAL:
+        case TEMP_CONST:
             state = TS_DEAD;
             break;
         default:
@@ -3173,15 +3235,28 @@  static void temp_load(TCGContext *, TCGTemp *, TCGRegSet, TCGRegSet, TCGRegSet);
    mark it free; otherwise mark it dead.  */
 static void temp_free_or_dead(TCGContext *s, TCGTemp *ts, int free_or_dead)
 {
-    if (temp_readonly(ts)) {
+    TCGTempVal new_type;
+
+    switch (ts->kind) {
+    case TEMP_FIXED:
         return;
+    case TEMP_GLOBAL:
+    case TEMP_LOCAL:
+        new_type = TEMP_VAL_MEM;
+        break;
+    case TEMP_NORMAL:
+        new_type = free_or_dead < 0 ? TEMP_VAL_MEM : TEMP_VAL_DEAD;
+        break;
+    case TEMP_CONST:
+        new_type = TEMP_VAL_CONST;
+        break;
+    default:
+        g_assert_not_reached();
     }
     if (ts->val_type == TEMP_VAL_REG) {
         s->reg_to_temp[ts->reg] = NULL;
     }
-    ts->val_type = (free_or_dead < 0
-                    || ts->kind != TEMP_NORMAL
-                    ? TEMP_VAL_MEM : TEMP_VAL_DEAD);
+    ts->val_type = new_type;
 }
 
 /* Mark a temporary as dead.  */
@@ -3197,10 +3272,7 @@  static inline void temp_dead(TCGContext *s, TCGTemp *ts)
 static void temp_sync(TCGContext *s, TCGTemp *ts, TCGRegSet allocated_regs,
                       TCGRegSet preferred_regs, int free_or_dead)
 {
-    if (temp_readonly(ts)) {
-        return;
-    }
-    if (!ts->mem_coherent) {
+    if (!temp_readonly(ts) && !ts->mem_coherent) {
         if (!ts->mem_allocated) {
             temp_allocate_frame(s, ts);
         }
@@ -3393,12 +3465,22 @@  static void tcg_reg_alloc_bb_end(TCGContext *s, TCGRegSet allocated_regs)
 
     for (i = s->nb_globals; i < s->nb_temps; i++) {
         TCGTemp *ts = &s->temps[i];
-        if (ts->kind == TEMP_LOCAL) {
+
+        switch (ts->kind) {
+        case TEMP_LOCAL:
             temp_save(s, ts, allocated_regs);
-        } else {
+            break;
+        case TEMP_NORMAL:
             /* The liveness analysis already ensures that temps are dead.
                Keep an tcg_debug_assert for safety. */
             tcg_debug_assert(ts->val_type == TEMP_VAL_DEAD);
+            break;
+        case TEMP_CONST:
+            /* Similarly, we should have freed any allocated register. */
+            tcg_debug_assert(ts->val_type == TEMP_VAL_CONST);
+            break;
+        default:
+            g_assert_not_reached();
         }
     }
 
@@ -3691,46 +3773,43 @@  static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op)
         i_preferred_regs = o_preferred_regs = 0;
         if (arg_ct->ct & TCG_CT_IALIAS) {
             o_preferred_regs = op->output_pref[arg_ct->alias_index];
-            if (ts->kind == TEMP_FIXED) {
-                /* if fixed register, we must allocate a new register
-                   if the alias is not the same register */
-                if (arg != op->args[arg_ct->alias_index]) {
-                    goto allocate_in_reg;
-                }
-            } else {
-                /* if the input is aliased to an output and if it is
-                   not dead after the instruction, we must allocate
-                   a new register and move it */
-                if (!IS_DEAD_ARG(i)) {
-                    goto allocate_in_reg;
-                }
 
-                /* check if the current register has already been allocated
-                   for another input aliased to an output */
-                if (ts->val_type == TEMP_VAL_REG) {
-                    int k2, i2;
-                    reg = ts->reg;
-                    for (k2 = 0 ; k2 < k ; k2++) {
-                        i2 = def->sorted_args[nb_oargs + k2];
-                        if ((def->args_ct[i2].ct & TCG_CT_IALIAS) &&
-                            reg == new_args[i2]) {
-                            goto allocate_in_reg;
-                        }
+            /*
+             * If the input is readonly, then it cannot also be an
+             * output and aliased to itself.  If the input is not
+             * dead after the instruction, we must allocate a new
+             * register and move it.
+             */
+            if (temp_readonly(ts) || !IS_DEAD_ARG(i)) {
+                goto allocate_in_reg;
+            }
+
+            /*
+             * Check if the current register has already been allocated
+             * for another input aliased to an output.
+             */
+            if (ts->val_type == TEMP_VAL_REG) {
+                reg = ts->reg;
+                for (int k2 = 0; k2 < k; k2++) {
+                    int i2 = def->sorted_args[nb_oargs + k2];
+                    if ((def->args_ct[i2].ct & TCG_CT_IALIAS) &&
+                        reg == new_args[i2]) {
+                        goto allocate_in_reg;
                     }
                 }
-                i_preferred_regs = o_preferred_regs;
             }
+            i_preferred_regs = o_preferred_regs;
         }
 
         temp_load(s, ts, arg_ct->u.regs, i_allocated_regs, i_preferred_regs);
         reg = ts->reg;
 
-        if (tcg_regset_test_reg(arg_ct->u.regs, reg)) {
-            /* nothing to do : the constraint is satisfied */
-        } else {
-        allocate_in_reg:
-            /* allocate a new register matching the constraint 
-               and move the temporary register into it */
+        if (!tcg_regset_test_reg(arg_ct->u.regs, reg)) {
+ allocate_in_reg:
+            /*
+             * Allocate a new register matching the constraint
+             * and move the temporary register into it.
+             */
             temp_load(s, ts, tcg_target_available_regs[ts->type],
                       i_allocated_regs, 0);
             reg = tcg_reg_alloc(s, arg_ct->u.regs, i_allocated_regs,
@@ -4189,6 +4268,13 @@  int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
     }
 #endif
 
+    for (i = 0; i < TCG_TYPE_COUNT; ++i) {
+        if (s->const_table[i]) {
+            g_hash_table_destroy(s->const_table[i]);
+            s->const_table[i] = NULL;
+        }
+    }
+
     tcg_reg_alloc_start(s);
 
     s->code_buf = tb->tc.ptr;