target/xtensa: prioritize load/store in FLIX bundles

Load/store opcodes may raise MMU exceptions. Normally exceptions should
be checked in priority order before any actual operations, but since MMU
exceptions are tightly coupled with actual memory access, there's
currently no way to do it.

Approximate this behavior by executing all load, then all store, and
then all other opcodes in the FLIX bundles. Use opcode dependency
mechanism to express ordering. Mark load/store opcodes with
XTENSA_OP_{LOAD,STORE} flags. Newer libisa has classifier functions that
can tell whether opcode is a load or store, but this information is not
available in the existing overlays.

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

2 files changed, 36 insertions, 5 deletions

diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h
index bf021f7..a01a94e 100644
--- a/target/xtensa/cpu.h
+++ b/target/xtensa/cpu.h
@@ -390,6 +390,10 @@ enum {
     XTENSA_OP_NAME_ARRAY = 0x8000,
 
     XTENSA_OP_CONTROL_FLOW = 0x10000,
+    XTENSA_OP_STORE = 0x20000,
+    XTENSA_OP_LOAD = 0x40000,
+    XTENSA_OP_LOAD_STORE =
+        XTENSA_OP_LOAD | XTENSA_OP_STORE,
 };
 
 typedef struct XtensaOpcodeOps {
diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index 5502b5c..338e6ca 100644
--- a/target/xtensa/translate.c
+++ b/target/xtensa/translate.c
@@ -986,6 +986,10 @@ static bool op_depends_on(const struct slot_prop *a,
     if (a->op_flags & XTENSA_OP_CONTROL_FLOW) {
         return true;
     }
+    if ((a->op_flags & XTENSA_OP_LOAD_STORE) <
+        (b->op_flags & XTENSA_OP_LOAD_STORE)) {
+        return true;
+    }
     while (i < a->n_out && j < b->n_in) {
         if (a->out[i].resource < b->in[j].resource) {
             ++i;
@@ -1017,6 +1021,10 @@ static bool break_dependency(struct slot_prop *a,
     if (a->op_flags & XTENSA_OP_CONTROL_FLOW) {
         return false;
     }
+    if ((a->op_flags & XTENSA_OP_LOAD_STORE) <
+        (b->op_flags & XTENSA_OP_LOAD_STORE)) {
+        return false;
+    }
     while (i < a->n_out && j < b->n_in) {
         if (a->out[i].resource < b->in[j].resource) {
             ++i;
@@ -1293,7 +1301,7 @@ static void disas_xtensa_insn(CPUXtensaState *env, DisasContext *dc)
         if (slots > 1) {
             slot_prop[slot].n_in = 0;
             slot_prop[slot].n_out = 0;
-            slot_prop[slot].op_flags = 0;
+            slot_prop[slot].op_flags = ops->op_flags & XTENSA_OP_LOAD_STORE;
 
             opnds = xtensa_opcode_num_operands(isa, opc);
 
@@ -3223,40 +3231,47 @@ static const XtensaOpcodeOps core_ops[] = {
         .name = "l16si",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TESW, false, false},
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "l16ui",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TEUW, false, false},
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "l32ai",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TEUL, true, false},
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "l32e",
         .translate = translate_l32e,
-        .op_flags = XTENSA_OP_PRIVILEGED,
+        .op_flags = XTENSA_OP_PRIVILEGED | XTENSA_OP_LOAD,
     }, {
         .name = (const char * const[]) {
             "l32i", "l32i.n", NULL,
         },
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TEUL, false, false},
-        .op_flags = XTENSA_OP_NAME_ARRAY,
+        .op_flags = XTENSA_OP_NAME_ARRAY | XTENSA_OP_LOAD,
     }, {
         .name = "l32r",
         .translate = translate_l32r,
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "l8ui",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_UB, false, false},
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "lddec",
         .translate = translate_mac16,
         .par = (const uint32_t[]){MAC16_NONE, 0, -4},
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "ldinc",
         .translate = translate_mac16,
         .par = (const uint32_t[]){MAC16_NONE, 0, 4},
+        .op_flags = XTENSA_OP_LOAD,
     }, {
         .name = "ldpte",
         .op_flags = XTENSA_OP_ILL,
@@ -4214,28 +4229,32 @@ static const XtensaOpcodeOps core_ops[] = {
         .name = "s16i",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TEUW, false, true},
+        .op_flags = XTENSA_OP_STORE,
     }, {
         .name = "s32c1i",
         .translate = translate_s32c1i,
+        .op_flags = XTENSA_OP_LOAD | XTENSA_OP_STORE,
     }, {
         .name = "s32e",
         .translate = translate_s32e,
-        .op_flags = XTENSA_OP_PRIVILEGED,
+        .op_flags = XTENSA_OP_PRIVILEGED | XTENSA_OP_STORE,
     }, {
         .name = (const char * const[]) {
             "s32i", "s32i.n", "s32nb", NULL,
         },
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TEUL, false, true},
-        .op_flags = XTENSA_OP_NAME_ARRAY,
+        .op_flags = XTENSA_OP_NAME_ARRAY | XTENSA_OP_STORE,
     }, {
         .name = "s32ri",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_TEUL, true, true},
+        .op_flags = XTENSA_OP_STORE,
     }, {
         .name = "s8i",
         .translate = translate_ldst,
         .par = (const uint32_t[]){MO_UB, false, true},
+        .op_flags = XTENSA_OP_STORE,
     }, {
         .name = "salt",
         .translate = translate_salt,
@@ -5525,21 +5544,25 @@ static const XtensaOpcodeOps fpu2000_ops[] = {
         .name = "lsi",
         .translate = translate_ldsti,
         .par = (const uint32_t[]){false, false},
+        .op_flags = XTENSA_OP_LOAD,
         .coprocessor = 0x1,
     }, {
         .name = "lsiu",
         .translate = translate_ldsti,
         .par = (const uint32_t[]){false, true},
+        .op_flags = XTENSA_OP_LOAD,
         .coprocessor = 0x1,
     }, {
         .name = "lsx",
         .translate = translate_ldstx,
         .par = (const uint32_t[]){false, false},
+        .op_flags = XTENSA_OP_LOAD,
         .coprocessor = 0x1,
     }, {
         .name = "lsxu",
         .translate = translate_ldstx,
         .par = (const uint32_t[]){false, true},
+        .op_flags = XTENSA_OP_LOAD,
         .coprocessor = 0x1,
     }, {
         .name = "madd.s",
@@ -5619,21 +5642,25 @@ static const XtensaOpcodeOps fpu2000_ops[] = {
         .name = "ssi",
         .translate = translate_ldsti,
         .par = (const uint32_t[]){true, false},
+        .op_flags = XTENSA_OP_STORE,
         .coprocessor = 0x1,
     }, {
         .name = "ssiu",
         .translate = translate_ldsti,
         .par = (const uint32_t[]){true, true},
+        .op_flags = XTENSA_OP_STORE,
         .coprocessor = 0x1,
     }, {
         .name = "ssx",
         .translate = translate_ldstx,
         .par = (const uint32_t[]){true, false},
+        .op_flags = XTENSA_OP_STORE,
         .coprocessor = 0x1,
     }, {
         .name = "ssxu",
         .translate = translate_ldstx,
         .par = (const uint32_t[]){true, true},
+        .op_flags = XTENSA_OP_STORE,
         .coprocessor = 0x1,
     }, {
         .name = "sub.s",