tcg: Optimize qemu_ld/st by generating slow paths at the end of a block

Add optimized TCG qemu_ld/st generation which locates the code of TLB miss
cases at the end of a block after generating the other IRs.
Currently, this optimization supports only i386 and x86_64 hosts.

Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

1 files changed, 278 insertions, 126 deletions

diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
index e45a5a0426..6f3ad3ceab 100644
--- a/tcg/i386/tcg-target.c
+++ b/tcg/i386/tcg-target.c
@@ -1002,6 +1002,17 @@ static const void *qemu_st_helpers[4] = {
     helper_stq_mmu,
 };
 
+static void add_qemu_ldst_label(TCGContext *s,
+                                int is_ld,
+                                int opc,
+                                int data_reg,
+                                int data_reg2,
+                                int addrlo_reg,
+                                int addrhi_reg,
+                                int mem_index,
+                                uint8_t *raddr,
+                                uint8_t **label_ptr);
+
 /* Perform the TLB load and compare.
 
    Inputs:
@@ -1060,19 +1071,19 @@ static inline void tcg_out_tlb_load(TCGContext *s, int addrlo_idx,
 
     tcg_out_mov(s, type, r1, addrlo);
 
-    /* jne label1 */
-    tcg_out8(s, OPC_JCC_short + JCC_JNE);
+    /* jne slow_path */
+    tcg_out_opc(s, OPC_JCC_long + JCC_JNE, 0, 0, 0);
     label_ptr[0] = s->code_ptr;
-    s->code_ptr++;
+    s->code_ptr += 4;
 
     if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
         /* cmp 4(r0), addrhi */
         tcg_out_modrm_offset(s, OPC_CMP_GvEv, args[addrlo_idx+1], r0, 4);
 
-        /* jne label1 */
-        tcg_out8(s, OPC_JCC_short + JCC_JNE);
+        /* jne slow_path */
+        tcg_out_opc(s, OPC_JCC_long + JCC_JNE, 0, 0, 0);
         label_ptr[1] = s->code_ptr;
-        s->code_ptr++;
+        s->code_ptr += 4;
     }
 
     /* TLB Hit.  */
@@ -1193,10 +1204,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args,
     int addrlo_idx;
 #if defined(CONFIG_SOFTMMU)
     int mem_index, s_bits;
-#if TCG_TARGET_REG_BITS == 32
-    int stack_adjust;
-#endif
-    uint8_t *label_ptr[3];
+    uint8_t *label_ptr[2];
 #endif
 
     data_reg = args[0];
@@ -1216,87 +1224,17 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args,
     /* TLB Hit.  */
     tcg_out_qemu_ld_direct(s, data_reg, data_reg2, TCG_REG_L1, 0, 0, opc);
 
-    /* jmp label2 */
-    tcg_out8(s, OPC_JMP_short);
-    label_ptr[2] = s->code_ptr;
-    s->code_ptr++;
-
-    /* TLB Miss.  */
-
-    /* label1: */
-    *label_ptr[0] = s->code_ptr - label_ptr[0] - 1;
-    if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
-        *label_ptr[1] = s->code_ptr - label_ptr[1] - 1;
-    }
-
-    /* XXX: move that code at the end of the TB */
-#if TCG_TARGET_REG_BITS == 32
-    tcg_out_pushi(s, mem_index);
-    stack_adjust = 4;
-    if (TARGET_LONG_BITS == 64) {
-        tcg_out_push(s, args[addrlo_idx + 1]);
-        stack_adjust += 4;
-    }
-    tcg_out_push(s, args[addrlo_idx]);
-    stack_adjust += 4;
-    tcg_out_push(s, TCG_AREG0);
-    stack_adjust += 4;
-#else
-    tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
-    /* The second argument is already loaded with addrlo.  */
-    tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[2], mem_index);
-#endif
-
-    tcg_out_calli(s, (tcg_target_long)qemu_ld_helpers[s_bits]);
-
-#if TCG_TARGET_REG_BITS == 32
-    if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
-        /* Pop and discard.  This is 2 bytes smaller than the add.  */
-        tcg_out_pop(s, TCG_REG_ECX);
-    } else if (stack_adjust != 0) {
-        tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
-    }
-#endif
-
-    switch(opc) {
-    case 0 | 4:
-        tcg_out_ext8s(s, data_reg, TCG_REG_EAX, P_REXW);
-        break;
-    case 1 | 4:
-        tcg_out_ext16s(s, data_reg, TCG_REG_EAX, P_REXW);
-        break;
-    case 0:
-        tcg_out_ext8u(s, data_reg, TCG_REG_EAX);
-        break;
-    case 1:
-        tcg_out_ext16u(s, data_reg, TCG_REG_EAX);
-        break;
-    case 2:
-        tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
-        break;
-#if TCG_TARGET_REG_BITS == 64
-    case 2 | 4:
-        tcg_out_ext32s(s, data_reg, TCG_REG_EAX);
-        break;
-#endif
-    case 3:
-        if (TCG_TARGET_REG_BITS == 64) {
-            tcg_out_mov(s, TCG_TYPE_I64, data_reg, TCG_REG_RAX);
-        } else if (data_reg == TCG_REG_EDX) {
-            /* xchg %edx, %eax */
-            tcg_out_opc(s, OPC_XCHG_ax_r32 + TCG_REG_EDX, 0, 0, 0);
-            tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EAX);
-        } else {
-            tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
-            tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EDX);
-        }
-        break;
-    default:
-        tcg_abort();
-    }
-
-    /* label2: */
-    *label_ptr[2] = s->code_ptr - label_ptr[2] - 1;
+    /* Record the current context of a load into ldst label */
+    add_qemu_ldst_label(s,
+                        1,
+                        opc,
+                        data_reg,
+                        data_reg2,
+                        args[addrlo_idx],
+                        args[addrlo_idx + 1],
+                        mem_index,
+                        s->code_ptr,
+                        label_ptr);
 #else
     {
         int32_t offset = GUEST_BASE;
@@ -1393,8 +1331,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
     int addrlo_idx;
 #if defined(CONFIG_SOFTMMU)
     int mem_index, s_bits;
-    int stack_adjust;
-    uint8_t *label_ptr[3];
+    uint8_t *label_ptr[2];
 #endif
 
     data_reg = args[0];
@@ -1414,20 +1351,221 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
     /* TLB Hit.  */
     tcg_out_qemu_st_direct(s, data_reg, data_reg2, TCG_REG_L1, 0, 0, opc);
 
-    /* jmp label2 */
+    /* Record the current context of a store into ldst label */
+    add_qemu_ldst_label(s,
+                        0,
+                        opc,
+                        data_reg,
+                        data_reg2,
+                        args[addrlo_idx],
+                        args[addrlo_idx + 1],
+                        mem_index,
+                        s->code_ptr,
+                        label_ptr);
+#else
+    {
+        int32_t offset = GUEST_BASE;
+        int base = args[addrlo_idx];
+        int seg = 0;
+
+        /* ??? We assume all operations have left us with register contents
+           that are zero extended.  So far this appears to be true.  If we
+           want to enforce this, we can either do an explicit zero-extension
+           here, or (if GUEST_BASE == 0, or a segment register is in use)
+           use the ADDR32 prefix.  For now, do nothing.  */
+        if (GUEST_BASE && guest_base_flags) {
+            seg = guest_base_flags;
+            offset = 0;
+        } else if (TCG_TARGET_REG_BITS == 64 && offset != GUEST_BASE) {
+            tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_L1, GUEST_BASE);
+            tgen_arithr(s, ARITH_ADD + P_REXW, TCG_REG_L1, base);
+            base = TCG_REG_L1;
+            offset = 0;
+        }
+
+        tcg_out_qemu_st_direct(s, data_reg, data_reg2, base, offset, seg, opc);
+    }
+#endif
+}
+
+#if defined(CONFIG_SOFTMMU)
+/*
+ * Record the context of a call to the out of line helper code for the slow path
+ * for a load or store, so that we can later generate the correct helper code
+ */
+static void add_qemu_ldst_label(TCGContext *s,
+                                int is_ld,
+                                int opc,
+                                int data_reg,
+                                int data_reg2,
+                                int addrlo_reg,
+                                int addrhi_reg,
+                                int mem_index,
+                                uint8_t *raddr,
+                                uint8_t **label_ptr)
+{
+    int idx;
+    TCGLabelQemuLdst *label;
+
+    if (s->nb_qemu_ldst_labels >= TCG_MAX_QEMU_LDST) {
+        tcg_abort();
+    }
+
+    idx = s->nb_qemu_ldst_labels++;
+    label = (TCGLabelQemuLdst *)&s->qemu_ldst_labels[idx];
+    label->is_ld = is_ld;
+    label->opc = opc;
+    label->datalo_reg = data_reg;
+    label->datahi_reg = data_reg2;
+    label->addrlo_reg = addrlo_reg;
+    label->addrhi_reg = addrhi_reg;
+    label->mem_index = mem_index;
+    label->raddr = raddr;
+    label->label_ptr[0] = label_ptr[0];
+    if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
+        label->label_ptr[1] = label_ptr[1];
+    }
+}
+
+/*
+ * Generate code for the slow path for a load at the end of block
+ */
+static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *label)
+{
+    int s_bits;
+    int opc = label->opc;
+    int mem_index = label->mem_index;
+#if TCG_TARGET_REG_BITS == 32
+    int stack_adjust;
+    int addrlo_reg = label->addrlo_reg;
+    int addrhi_reg = label->addrhi_reg;
+#endif
+    int data_reg = label->datalo_reg;
+    int data_reg2 = label->datahi_reg;
+    uint8_t *raddr = label->raddr;
+    uint8_t **label_ptr = &label->label_ptr[0];
+
+    s_bits = opc & 3;
+
+    /* resolve label address */
+    *(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4);
+    if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
+        *(uint32_t *)label_ptr[1] = (uint32_t)(s->code_ptr - label_ptr[1] - 4);
+    }
+
+#if TCG_TARGET_REG_BITS == 32
+    tcg_out_pushi(s, mem_index);
+    stack_adjust = 4;
+    if (TARGET_LONG_BITS == 64) {
+        tcg_out_push(s, addrhi_reg);
+        stack_adjust += 4;
+    }
+    tcg_out_push(s, addrlo_reg);
+    stack_adjust += 4;
+    tcg_out_push(s, TCG_AREG0);
+    stack_adjust += 4;
+#else
+    tcg_out_mov(s, TCG_TYPE_I64, tcg_target_call_iarg_regs[0], TCG_AREG0);
+    /* The second argument is already loaded with addrlo.  */
+    tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[2], mem_index);
+#endif
+
+    /* Code generation of qemu_ld/st's slow path calling MMU helper
+
+       PRE_PROC ...
+       call MMU helper
+       jmp POST_PROC (2b) : short forward jump <- GETRA()
+       jmp next_code (5b) : dummy long backward jump which is never executed
+       POST_PROC ... : do post-processing <- GETRA() + 7
+       jmp next_code : jump to the code corresponding to next IR of qemu_ld/st
+    */
+
+    tcg_out_calli(s, (tcg_target_long)qemu_ld_helpers[s_bits]);
+
+    /* Jump to post-processing code */
     tcg_out8(s, OPC_JMP_short);
-    label_ptr[2] = s->code_ptr;
-    s->code_ptr++;
+    tcg_out8(s, 5);
+    /* Dummy backward jump having information of fast path'pc for MMU helpers */
+    tcg_out8(s, OPC_JMP_long);
+    *(int32_t *)s->code_ptr = (int32_t)(raddr - s->code_ptr - 4);
+    s->code_ptr += 4;
 
-    /* TLB Miss.  */
+#if TCG_TARGET_REG_BITS == 32
+    if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
+        /* Pop and discard.  This is 2 bytes smaller than the add.  */
+        tcg_out_pop(s, TCG_REG_ECX);
+    } else if (stack_adjust != 0) {
+        tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
+    }
+#endif
 
-    /* label1: */
-    *label_ptr[0] = s->code_ptr - label_ptr[0] - 1;
+    switch(opc) {
+    case 0 | 4:
+        tcg_out_ext8s(s, data_reg, TCG_REG_EAX, P_REXW);
+        break;
+    case 1 | 4:
+        tcg_out_ext16s(s, data_reg, TCG_REG_EAX, P_REXW);
+        break;
+    case 0:
+        tcg_out_ext8u(s, data_reg, TCG_REG_EAX);
+        break;
+    case 1:
+        tcg_out_ext16u(s, data_reg, TCG_REG_EAX);
+        break;
+    case 2:
+        tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
+        break;
+#if TCG_TARGET_REG_BITS == 64
+    case 2 | 4:
+        tcg_out_ext32s(s, data_reg, TCG_REG_EAX);
+        break;
+#endif
+    case 3:
+        if (TCG_TARGET_REG_BITS == 64) {
+            tcg_out_mov(s, TCG_TYPE_I64, data_reg, TCG_REG_RAX);
+        } else if (data_reg == TCG_REG_EDX) {
+            /* xchg %edx, %eax */
+            tcg_out_opc(s, OPC_XCHG_ax_r32 + TCG_REG_EDX, 0, 0, 0);
+            tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EAX);
+        } else {
+            tcg_out_mov(s, TCG_TYPE_I32, data_reg, TCG_REG_EAX);
+            tcg_out_mov(s, TCG_TYPE_I32, data_reg2, TCG_REG_EDX);
+        }
+        break;
+    default:
+        tcg_abort();
+    }
+
+    /* Jump to the code corresponding to next IR of qemu_st */
+    tcg_out_jmp(s, (tcg_target_long)raddr);
+}
+
+/*
+ * Generate code for the slow path for a store at the end of block
+ */
+static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *label)
+{
+    int s_bits;
+    int stack_adjust;
+    int opc = label->opc;
+    int mem_index = label->mem_index;
+    int data_reg = label->datalo_reg;
+#if TCG_TARGET_REG_BITS == 32
+    int data_reg2 = label->datahi_reg;
+    int addrlo_reg = label->addrlo_reg;
+    int addrhi_reg = label->addrhi_reg;
+#endif
+    uint8_t *raddr = label->raddr;
+    uint8_t **label_ptr = &label->label_ptr[0];
+
+    s_bits = opc & 3;
+
+    /* resolve label address */
+    *(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4);
     if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) {
-        *label_ptr[1] = s->code_ptr - label_ptr[1] - 1;
+        *(uint32_t *)label_ptr[1] = (uint32_t)(s->code_ptr - label_ptr[1] - 4);
     }
 
-    /* XXX: move that code at the end of the TB */
 #if TCG_TARGET_REG_BITS == 32
     tcg_out_pushi(s, mem_index);
     stack_adjust = 4;
@@ -1438,10 +1576,10 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
     tcg_out_push(s, data_reg);
     stack_adjust += 4;
     if (TARGET_LONG_BITS == 64) {
-        tcg_out_push(s, args[addrlo_idx + 1]);
+        tcg_out_push(s, addrhi_reg);
         stack_adjust += 4;
     }
-    tcg_out_push(s, args[addrlo_idx]);
+    tcg_out_push(s, addrlo_reg);
     stack_adjust += 4;
     tcg_out_push(s, TCG_AREG0);
     stack_adjust += 4;
@@ -1454,8 +1592,26 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
     stack_adjust = 0;
 #endif
 
+    /* Code generation of qemu_ld/st's slow path calling MMU helper
+
+       PRE_PROC ...
+       call MMU helper
+       jmp POST_PROC (2b) : short forward jump <- GETRA()
+       jmp next_code (5b) : dummy long backward jump which is never executed
+       POST_PROC ... : do post-processing <- GETRA() + 7
+       jmp next_code : jump to the code corresponding to next IR of qemu_ld/st
+    */
+
     tcg_out_calli(s, (tcg_target_long)qemu_st_helpers[s_bits]);
 
+    /* Jump to post-processing code */
+    tcg_out8(s, OPC_JMP_short);
+    tcg_out8(s, 5);
+    /* Dummy backward jump having information of fast path'pc for MMU helpers */
+    tcg_out8(s, OPC_JMP_long);
+    *(int32_t *)s->code_ptr = (int32_t)(raddr - s->code_ptr - 4);
+    s->code_ptr += 4;
+
     if (stack_adjust == (TCG_TARGET_REG_BITS / 8)) {
         /* Pop and discard.  This is 2 bytes smaller than the add.  */
         tcg_out_pop(s, TCG_REG_ECX);
@@ -1463,33 +1619,29 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
         tcg_out_addi(s, TCG_REG_CALL_STACK, stack_adjust);
     }
 
-    /* label2: */
-    *label_ptr[2] = s->code_ptr - label_ptr[2] - 1;
-#else
-    {
-        int32_t offset = GUEST_BASE;
-        int base = args[addrlo_idx];
-        int seg = 0;
+    /* Jump to the code corresponding to next IR of qemu_st */
+    tcg_out_jmp(s, (tcg_target_long)raddr);
+}
 
-        /* ??? We assume all operations have left us with register contents
-           that are zero extended.  So far this appears to be true.  If we
-           want to enforce this, we can either do an explicit zero-extension
-           here, or (if GUEST_BASE == 0, or a segment register is in use)
-           use the ADDR32 prefix.  For now, do nothing.  */
-        if (GUEST_BASE && guest_base_flags) {
-            seg = guest_base_flags;
-            offset = 0;
-        } else if (TCG_TARGET_REG_BITS == 64 && offset != GUEST_BASE) {
-            tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_L1, GUEST_BASE);
-            tgen_arithr(s, ARITH_ADD + P_REXW, TCG_REG_L1, base);
-            base = TCG_REG_L1;
-            offset = 0;
+/*
+ * Generate TB finalization at the end of block
+ */
+void tcg_out_tb_finalize(TCGContext *s)
+{
+    int i;
+    TCGLabelQemuLdst *label;
+
+    /* qemu_ld/st slow paths */
+    for (i = 0; i < s->nb_qemu_ldst_labels; i++) {
+        label = (TCGLabelQemuLdst *)&s->qemu_ldst_labels[i];
+        if (label->is_ld) {
+            tcg_out_qemu_ld_slow_path(s, label);
+        } else {
+            tcg_out_qemu_st_slow_path(s, label);
         }
-
-        tcg_out_qemu_st_direct(s, data_reg, data_reg2, base, offset, seg, opc);
     }
-#endif
 }
+#endif  /* CONFIG_SOFTMMU */
 
 static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
                               const TCGArg *args, const int *const_args)