[interp] Skip NOPs when checking previous instruction

When emitting stloc.np, which looks for stloc/ldloc pair.

Commit migrated from https://github.com/mono/mono/commit/fc100ae04315a8954881169eee5cdf156a43b48c

diff --git a/src/mono/mono/mini/interp/transform.c b/src/mono/mono/mini/interp/transform.c
index 3b28402..c1de2a6 100644 (file)
--- a/src/mono/mono/mini/interp/transform.c
+++ b/src/mono/mono/mini/interp/transform.c
@@ -379,6 +379,15 @@ interp_clear_ins (TransformData *td, InterpInst *ins)
        ins->opcode = MINT_NOP;
 }
 
+static InterpInst*
+interp_prev_ins (InterpInst *ins)
+{
+       ins = ins->prev;
+       while (ins && ins->opcode == MINT_NOP)
+               ins = ins->prev;
+       return ins;
+}
+
 #define CHECK_STACK(td, n) \
        do { \
                int stack_size = (td)->sp - (td)->stack; \
@@ -1034,6 +1043,10 @@ interp_is_bb_start (TransformData *td, InterpInst *start, InterpInst *end)
                }
                ins = ins->next;
        }
+
+       // Also check if end is bb start
+       if (ins != NULL && ins->il_offset != -1 && td->is_bb_start [ins->il_offset])
+               return TRUE;
        return FALSE;
 }
 
@@ -6410,8 +6423,9 @@ interp_cprop (TransformData *td)
                        int replace_op = 0;
                        int loaded_local = ins->data [0];
                        local_ref_count [loaded_local]++;
-                       if (!is_bb_start && MINT_IS_STLOC (ins->prev->opcode) && ins->prev->data [0] == loaded_local) {
-                               int mt = ins->prev->opcode - MINT_STLOC_I1;
+                       InterpInst *prev_ins = interp_prev_ins (ins);
+                       if (MINT_IS_STLOC (prev_ins->opcode) && !interp_is_bb_start (td, prev_ins, ins) && prev_ins->data [0] == loaded_local) {
+                               int mt = prev_ins->opcode - MINT_STLOC_I1;
                                if (ins->opcode - MINT_LDLOC_I1 == mt) {
                                        if (mt == MINT_TYPE_I4)
                                                replace_op = MINT_STLOC_NP_I4;
@@ -6419,14 +6433,14 @@ interp_cprop (TransformData *td)
                                                replace_op = MINT_STLOC_NP_O;
                                        if (replace_op) {
                                                if (td->verbose_level)
-                                                       g_print ("Add stloc.np : ldloc (off %p), stloc (off %p)\n", ins->il_offset, ins->prev->il_offset);
+                                                       g_print ("Add stloc.np : ldloc (off %p), stloc (off %p)\n", ins->il_offset, prev_ins->il_offset);
                                                // We know what local is on the stack now. Track it
                                                sp->ins = NULL;
                                                sp->val.opcode = ins->opcode;
                                                sp->val.data = loaded_local;
 
                                                // Clear the previous stloc instruction
-                                               interp_clear_ins (td, ins->prev);
+                                               interp_clear_ins (td, prev_ins);
                                                ins->opcode = replace_op;
                                                mono_interp_stats.stloc_nps++;
                                                local_ref_count [loaded_local]--;