target-xtensa: implement loop option

See ISA, 4.3.2 for details.

Operations that change LEND SR value invalidate TBs at the old and at
the new LEND. LEND value at TB compilation time is considered constant
and loop instruction is generated based on this value.

Invalidation may be avoided for the TB at the old LEND address, since
looping code verifies actual LEND value.

Invalidation may be avoided for the TB at the new LEND address if
there's a way to associate LEND address with TB at compilation time and
later verify that it doesn't change.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

diff --git a/target-xtensa/cpu.h b/target-xtensa/cpu.h
index 7e662f5402fe4dea08153ac0871ae10f242bd6d3..97badf26c87c98b70c61b10ae262683c57ddd7c4 100644 (file)
--- a/target-xtensa/cpu.h
+++ b/target-xtensa/cpu.h
@@ -106,6 +106,9 @@ enum {
 };
 
 enum {
+    LBEG = 0,
+    LEND = 1,
+    LCOUNT = 2,
     SAR = 3,
     SCOMPARE1 = 12,
     WINDOW_BASE = 72,

diff --git a/target-xtensa/helpers.h b/target-xtensa/helpers.h
index 0971fde8da4792a707d0416c5dffde2d2c3ddc5f..b318c5a82c6541d610212ebadeb84fde0d27bbc3 100644 (file)
--- a/target-xtensa/helpers.h
+++ b/target-xtensa/helpers.h
@@ -12,6 +12,8 @@ DEF_HELPER_1(rotw, void, i32)
 DEF_HELPER_2(window_check, void, i32, i32)
 DEF_HELPER_0(restore_owb, void)
 DEF_HELPER_1(movsp, void, i32)
+DEF_HELPER_1(wsr_lbeg, void, i32)
+DEF_HELPER_1(wsr_lend, void, i32)
 DEF_HELPER_0(dump_state, void)
 
 #include "def-helper.h"

diff --git a/target-xtensa/op_helper.c b/target-xtensa/op_helper.c
index 7c3fb88a96047345093896e125dd75698b8febc1..5e0f56f6da841c2155e1d57738fee0f9b6a6be2e 100644 (file)
--- a/target-xtensa/op_helper.c
+++ b/target-xtensa/op_helper.c
@@ -288,6 +288,26 @@ void HELPER(movsp)(uint32_t pc)
     }
 }
 
+void HELPER(wsr_lbeg)(uint32_t v)
+{
+    if (env->sregs[LBEG] != v) {
+        tb_invalidate_phys_page_range(
+                env->sregs[LEND] - 1, env->sregs[LEND], 0);
+        env->sregs[LBEG] = v;
+    }
+}
+
+void HELPER(wsr_lend)(uint32_t v)
+{
+    if (env->sregs[LEND] != v) {
+        tb_invalidate_phys_page_range(
+                env->sregs[LEND] - 1, env->sregs[LEND], 0);
+        env->sregs[LEND] = v;
+        tb_invalidate_phys_page_range(
+                env->sregs[LEND] - 1, env->sregs[LEND], 0);
+    }
+}
+
 void HELPER(dump_state)(void)
 {
     cpu_dump_state(env, stderr, fprintf, 0);

diff --git a/target-xtensa/translate.c b/target-xtensa/translate.c
index 7a2e07ff6080578e39c93846ae257895876f065c..8f4500750c35d6ecd7743b3834d71cf3cbb4b051 100644 (file)
--- a/target-xtensa/translate.c
+++ b/target-xtensa/translate.c
@@ -47,6 +47,8 @@ typedef struct DisasContext {
     uint32_t next_pc;
     int cring;
     int ring;
+    uint32_t lbeg;
+    uint32_t lend;
     int is_jmp;
     int singlestep_enabled;
 
@@ -65,6 +67,9 @@ static TCGv_i32 cpu_UR[256];
 #include "gen-icount.h"
 
 static const char * const sregnames[256] = {
+    [LBEG] = "LBEG",
+    [LEND] = "LEND",
+    [LCOUNT] = "LCOUNT",
     [SAR] = "SAR",
     [SCOMPARE1] = "SCOMPARE1",
     [WINDOW_BASE] = "WINDOW_BASE",
@@ -247,13 +252,37 @@ static void gen_callwi(DisasContext *dc, int callinc, uint32_t dest, int slot)
     tcg_temp_free(tmp);
 }
 
+static bool gen_check_loop_end(DisasContext *dc, int slot)
+{
+    if (option_enabled(dc, XTENSA_OPTION_LOOP) &&
+            !(dc->tb->flags & XTENSA_TBFLAG_EXCM) &&
+            dc->next_pc == dc->lend) {
+        int label = gen_new_label();
+
+        tcg_gen_brcondi_i32(TCG_COND_EQ, cpu_SR[LCOUNT], 0, label);
+        tcg_gen_subi_i32(cpu_SR[LCOUNT], cpu_SR[LCOUNT], 1);
+        gen_jumpi(dc, dc->lbeg, slot);
+        gen_set_label(label);
+        gen_jumpi(dc, dc->next_pc, -1);
+        return true;
+    }
+    return false;
+}
+
+static void gen_jumpi_check_loop_end(DisasContext *dc, int slot)
+{
+    if (!gen_check_loop_end(dc, slot)) {
+        gen_jumpi(dc, dc->next_pc, slot);
+    }
+}
+
 static void gen_brcond(DisasContext *dc, TCGCond cond,
         TCGv_i32 t0, TCGv_i32 t1, uint32_t offset)
 {
     int label = gen_new_label();
 
     tcg_gen_brcond_i32(cond, t0, t1, label);
-    gen_jumpi(dc, dc->next_pc, 0);
+    gen_jumpi_check_loop_end(dc, 0);
     gen_set_label(label);
     gen_jumpi(dc, dc->pc + offset, 1);
 }
@@ -283,6 +312,16 @@ static void gen_rsr(DisasContext *dc, TCGv_i32 d, uint32_t sr)
     }
 }
 
+static void gen_wsr_lbeg(DisasContext *dc, uint32_t sr, TCGv_i32 s)
+{
+    gen_helper_wsr_lbeg(s);
+}
+
+static void gen_wsr_lend(DisasContext *dc, uint32_t sr, TCGv_i32 s)
+{
+    gen_helper_wsr_lend(s);
+}
+
 static void gen_wsr_sar(DisasContext *dc, uint32_t sr, TCGv_i32 s)
 {
     tcg_gen_andi_i32(cpu_SR[sr], s, 0x3f);
@@ -308,13 +347,15 @@ static void gen_wsr_ps(DisasContext *dc, uint32_t sr, TCGv_i32 v)
     }
     tcg_gen_andi_i32(cpu_SR[sr], v, mask);
     /* This can change mmu index, so exit tb */
-    gen_jumpi(dc, dc->next_pc, -1);
+    gen_jumpi_check_loop_end(dc, -1);
 }
 
 static void gen_wsr(DisasContext *dc, uint32_t sr, TCGv_i32 s)
 {
     static void (* const wsr_handler[256])(DisasContext *dc,
             uint32_t sr, TCGv_i32 v) = {
+        [LBEG] = gen_wsr_lbeg,
+        [LEND] = gen_wsr_lend,
         [SAR] = gen_wsr_sar,
         [WINDOW_BASE] = gen_wsr_windowbase,
         [PS] = gen_wsr_ps,
@@ -1542,15 +1583,29 @@ static void disas_xtensa_insn(DisasContext *dc)
                     break;
 
                 case 8: /*LOOP*/
-                    TBD();
-                    break;
-
                 case 9: /*LOOPNEZ*/
-                    TBD();
-                    break;
-
                 case 10: /*LOOPGTZ*/
-                    TBD();
+                    HAS_OPTION(XTENSA_OPTION_LOOP);
+                    {
+                        uint32_t lend = dc->pc + RRI8_IMM8 + 4;
+                        TCGv_i32 tmp = tcg_const_i32(lend);
+
+                        tcg_gen_subi_i32(cpu_SR[LCOUNT], cpu_R[RRI8_S], 1);
+                        tcg_gen_movi_i32(cpu_SR[LBEG], dc->next_pc);
+                        gen_wsr_lend(dc, LEND, tmp);
+                        tcg_temp_free(tmp);
+
+                        if (BRI8_R > 8) {
+                            int label = gen_new_label();
+                            tcg_gen_brcondi_i32(
+                                    BRI8_R == 9 ? TCG_COND_NE : TCG_COND_GT,
+                                    cpu_R[RRI8_S], 0, label);
+                            gen_jumpi(dc, lend, 1);
+                            gen_set_label(label);
+                        }
+
+                        gen_jumpi(dc, dc->next_pc, 0);
+                    }
                     break;
 
                 default: /*reserved*/
@@ -1727,7 +1782,9 @@ static void disas_xtensa_insn(DisasContext *dc)
         break;
     }
 
+    gen_check_loop_end(dc, 0);
     dc->pc = dc->next_pc;
+
     return;
 
 invalid_opcode:
@@ -1773,6 +1830,8 @@ static void gen_intermediate_code_internal(
     dc.pc = pc_start;
     dc.ring = tb->flags & XTENSA_TBFLAG_RING_MASK;
     dc.cring = (tb->flags & XTENSA_TBFLAG_EXCM) ? 0 : dc.ring;
+    dc.lbeg = env->sregs[LBEG];
+    dc.lend = env->sregs[LEND];
     dc.is_jmp = DISAS_NEXT;
 
     init_sar_tracker(&dc);