Hexagon (target/hexagon) Make special new_value for USR

Precursor to moving new_value from the global state to DisasContext

USR will need to stay in the global state because some helpers will
set it's value

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230427230012.3800327-17-tsimpson@quicinc.com>

target/hexagon/README

@@ -186,7 +186,7 @@ We also generate an analyze_<tag> function for each instruction.  Currently,
 these functions record the writes to registers by calling ctx_log_*.  During
 gen_start_packet, we invoke the analyze_<tag> function for each instruction in
 the packet, and we mark the implicit writes.  After the analysis is performed,
-we initialize hex_new_value for each of the predicated assignments.
+we initialize the result register for each of the predicated assignments.
 
 In addition to instruction semantics, we use a generator to create the decode
 tree.  This generation is also a two step process.  The first step is to run

target/hexagon/cpu.h

@@ -90,6 +90,7 @@ typedef struct CPUArchState {
 
     uint8_t slot_cancelled;
     target_ulong new_value[TOTAL_PER_THREAD_REGS];
+    target_ulong new_value_usr;
 
     /*
      * Only used when HEX_DEBUG is on, but unconditionally included

target/hexagon/gen_tcg_funcs.py

@@ -190,7 +190,7 @@ def genptr_decl_new(f, tag, regtype, regid, regno):
         if regid in {"s", "t"}:
             f.write(
                 f"    TCGv {regtype}{regid}N = "
-                f"hex_new_value[insn->regno[{regno}]];\n"
+                f"get_result_gpr(ctx, insn->regno[{regno}]);\n"
             )
         else:
             print("Bad register parse: ", regtype, regid)

target/hexagon/genptr.c

@@ -68,10 +68,14 @@ static inline void gen_masked_reg_write(TCGv new_val, TCGv cur_val,
     }
 }
 
-static TCGv get_result_gpr(DisasContext *ctx, int rnum)
+TCGv get_result_gpr(DisasContext *ctx, int rnum)
 {
     if (ctx->need_commit) {
-        return hex_new_value[rnum];
+        if (rnum == HEX_REG_USR) {
+            return hex_new_value_usr;
+        } else {
+            return hex_new_value[rnum];
+        }
     } else {
         return hex_gpr[rnum];
     }

target/hexagon/genptr.h

@@ -35,6 +35,7 @@ void gen_store4i(TCGv_env cpu_env, TCGv vaddr, int32_t src, uint32_t slot);
 void gen_store8i(TCGv_env cpu_env, TCGv vaddr, int64_t src, uint32_t slot);
 TCGv gen_read_reg(TCGv result, int num);
 TCGv gen_read_preg(TCGv pred, uint8_t num);
+TCGv get_result_gpr(DisasContext *ctx, int rnum);
 TCGv get_result_pred(DisasContext *ctx, int pnum);
 void gen_log_reg_write(DisasContext *ctx, int rnum, TCGv val);
 void gen_log_pred_write(DisasContext *ctx, int pnum, TCGv val);

target/hexagon/macros.h

@@ -46,7 +46,7 @@
 #define SET_USR_FIELD(FIELD, VAL) \
     do { \
         if (pkt_need_commit) { \
-            fINSERT_BITS(env->new_value[HEX_REG_USR], \
+            fINSERT_BITS(env->new_value_usr, \
                         reg_field_info[FIELD].width, \
                         reg_field_info[FIELD].offset, (VAL)); \
         } else { \

target/hexagon/translate.c

@@ -45,6 +45,7 @@ TCGv hex_this_PC;
 TCGv hex_slot_cancelled;
 TCGv hex_branch_taken;
 TCGv hex_new_value[TOTAL_PER_THREAD_REGS];
+TCGv hex_new_value_usr;
 TCGv hex_reg_written[TOTAL_PER_THREAD_REGS];
 TCGv hex_new_pred_value[NUM_PREGS];
 TCGv hex_pred_written;
@@ -547,12 +548,12 @@ static void gen_start_packet(DisasContext *ctx)
         tcg_gen_movi_tl(hex_pred_written, 0);
     }
 
-    /* Preload the predicated registers into hex_new_value[i] */
+    /* Preload the predicated registers into get_result_gpr(ctx, i) */
     if (ctx->need_commit &&
         !bitmap_empty(ctx->predicated_regs, TOTAL_PER_THREAD_REGS)) {
         int i = find_first_bit(ctx->predicated_regs, TOTAL_PER_THREAD_REGS);
         while (i < TOTAL_PER_THREAD_REGS) {
-            tcg_gen_mov_tl(hex_new_value[i], hex_gpr[i]);
+            tcg_gen_mov_tl(get_result_gpr(ctx, i), hex_gpr[i]);
             i = find_next_bit(ctx->predicated_regs, TOTAL_PER_THREAD_REGS,
                               i + 1);
         }
@@ -667,7 +668,7 @@ static void gen_reg_writes(DisasContext *ctx)
     for (i = 0; i < ctx->reg_log_idx; i++) {
         int reg_num = ctx->reg_log[i];
 
-        tcg_gen_mov_tl(hex_gpr[reg_num], hex_new_value[reg_num]);
+        tcg_gen_mov_tl(hex_gpr[reg_num], get_result_gpr(ctx, reg_num));
 
         /*
          * ctx->is_tight_loop is set when SA0 points to the beginning of the TB.
@@ -1180,10 +1181,14 @@ void hexagon_translate_init(void)
             offsetof(CPUHexagonState, gpr[i]),
             hexagon_regnames[i]);
 
-        snprintf(new_value_names[i], NAME_LEN, "new_%s", hexagon_regnames[i]);
-        hex_new_value[i] = tcg_global_mem_new(cpu_env,
-            offsetof(CPUHexagonState, new_value[i]),
-            new_value_names[i]);
+        if (i == HEX_REG_USR) {
+            hex_new_value[i] = NULL;
+        } else {
+            snprintf(new_value_names[i], NAME_LEN, "new_%s", hexagon_regnames[i]);
+            hex_new_value[i] = tcg_global_mem_new(cpu_env,
+                offsetof(CPUHexagonState, new_value[i]),
+                new_value_names[i]);
+        }
 
         if (HEX_DEBUG) {
             snprintf(reg_written_names[i], NAME_LEN, "reg_written_%s",
@@ -1193,6 +1198,9 @@ void hexagon_translate_init(void)
                 reg_written_names[i]);
         }
     }
+    hex_new_value_usr = tcg_global_mem_new(cpu_env,
+        offsetof(CPUHexagonState, new_value_usr), "new_value_usr");
+
     for (i = 0; i < NUM_PREGS; i++) {
         hex_pred[i] = tcg_global_mem_new(cpu_env,
             offsetof(CPUHexagonState, pred[i]),

target/hexagon/translate.h

@@ -191,6 +191,7 @@ extern TCGv hex_this_PC;
 extern TCGv hex_slot_cancelled;
 extern TCGv hex_branch_taken;
 extern TCGv hex_new_value[TOTAL_PER_THREAD_REGS];
+extern TCGv hex_new_value_usr;
 extern TCGv hex_reg_written[TOTAL_PER_THREAD_REGS];
 extern TCGv hex_new_pred_value[NUM_PREGS];
 extern TCGv hex_pred_written;