[Qemu-devel] [PULL 6/8] tcg: Remove opcodes instead of noping them out

[Richard Henderson <rth@twiddle.net>]

With the linked list scheme we need not leave nops in the stream
that we need to process later.

Reviewed-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 tcg/optimize.c | 14 +++++++-------
 tcg/tcg.c      | 28 ++++++++++++++++++++++++----
 tcg/tcg.h      |  1 +
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index f2b8acf..973fbb4 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -758,7 +758,7 @@ static void tcg_constant_folding(TCGContext *s)
             break;
         do_mov3:
             if (temps_are_copies(args[0], args[1])) {
-                op->opc = INDEX_op_nop;
+                tcg_op_remove(s, op);
             } else {
                 tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
             }
@@ -916,7 +916,7 @@ static void tcg_constant_folding(TCGContext *s)
         if (affected == 0) {
             assert(nb_oargs == 1);
             if (temps_are_copies(args[0], args[1])) {
-                op->opc = INDEX_op_nop;
+                tcg_op_remove(s, op);
             } else if (temps[args[1]].state != TCG_TEMP_CONST) {
                 tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
             } else {
@@ -948,7 +948,7 @@ static void tcg_constant_folding(TCGContext *s)
         CASE_OP_32_64(and):
             if (temps_are_copies(args[1], args[2])) {
                 if (temps_are_copies(args[0], args[1])) {
-                    op->opc = INDEX_op_nop;
+                    tcg_op_remove(s, op);
                 } else {
                     tcg_opt_gen_mov(s, op, args, opc, args[0], args[1]);
                 }
@@ -979,7 +979,7 @@ static void tcg_constant_folding(TCGContext *s)
         switch (opc) {
         CASE_OP_32_64(mov):
             if (temps_are_copies(args[0], args[1])) {
-                op->opc = INDEX_op_nop;
+                tcg_op_remove(s, op);
                 break;
             }
             if (temps[args[1]].state != TCG_TEMP_CONST) {
@@ -1074,7 +1074,7 @@ static void tcg_constant_folding(TCGContext *s)
                     op->opc = INDEX_op_br;
                     args[0] = args[3];
                 } else {
-                    op->opc = INDEX_op_nop;
+                    tcg_op_remove(s, op);
                 }
                 break;
             }
@@ -1084,7 +1084,7 @@ static void tcg_constant_folding(TCGContext *s)
             tmp = do_constant_folding_cond(opc, args[1], args[2], args[5]);
             if (tmp != 2) {
                 if (temps_are_copies(args[0], args[4-tmp])) {
-                    op->opc = INDEX_op_nop;
+                    tcg_op_remove(s, op);
                 } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {
                     tcg_opt_gen_movi(s, op, args, opc,
                                      args[0], temps[args[4-tmp]].val);
@@ -1177,7 +1177,7 @@ static void tcg_constant_folding(TCGContext *s)
                     args[0] = args[5];
                 } else {
             do_brcond_false:
-                    op->opc = INDEX_op_nop;
+                    tcg_op_remove(s, op);
                 }
             } else if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
                        && temps[args[2]].state == TCG_TEMP_CONST
diff --git a/tcg/tcg.c b/tcg/tcg.c
index ee041b9..4115e8b 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1244,6 +1244,29 @@ void tcg_add_target_add_op_defs(const TCGTargetOpDef *tdefs)
 #endif
 }
 
+void tcg_op_remove(TCGContext *s, TCGOp *op)
+{
+    int next = op->next;
+    int prev = op->prev;
+
+    if (next >= 0) {
+        s->gen_op_buf[next].prev = prev;
+    } else {
+        s->gen_last_op_idx = prev;
+    }
+    if (prev >= 0) {
+        s->gen_op_buf[prev].next = next;
+    } else {
+        s->gen_first_op_idx = next;
+    }
+
+    *op = (TCGOp){ .opc = INDEX_op_nop, .next = -1, .prev = -1 };
+
+#ifdef CONFIG_PROFILER
+    s->del_op_count++;
+#endif
+}
+
 #ifdef USE_LIVENESS_ANALYSIS
 /* liveness analysis: end of function: all temps are dead, and globals
    should be in memory. */
@@ -1466,10 +1489,7 @@ static void tcg_liveness_analysis(TCGContext *s)
                     }
                 }
             do_remove:
-                op->opc = INDEX_op_nop;
-#ifdef CONFIG_PROFILER
-                s->del_op_count++;
-#endif
+                tcg_op_remove(s, op);
             } else {
             do_not_remove:
                 /* output args are dead */
diff --git a/tcg/tcg.h b/tcg/tcg.h
index 596e30a..f941965 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -743,6 +743,7 @@ void tcg_add_target_add_op_defs(const TCGTargetOpDef *tdefs);
 void tcg_gen_callN(TCGContext *s, void *func,
                    TCGArg ret, int nargs, TCGArg *args);
 
+void tcg_op_remove(TCGContext *s, TCGOp *op);
 void tcg_optimize(TCGContext *s);
 
 /* only used for debugging purposes */
-- 
2.1.0