target/hexagon: rename aliased register HEX_REG_P3_0

The patch renames the identifier of the 32bit register
HEX_REG_P3_0 to HEX_REG_P3_0_ALIASED.

This change is to intended to provide some warning that
HEX_REG_P3_0 is an aliased register which has multiple
representations in CPU state and therefore might require
special handling in some contexts. The hope is to prevent
accidental misuse of this register e.g the issue reported
for the signals tests failure [here][1].

[1]: https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg01102.html

Signed-off-by: Mukilan Thiyagarajan <quic_mthiyaga@quicinc.com>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221229092006.10709-3-quic_mthiyaga@quicinc.com>

diff --git a/target/hexagon/cpu.c b/target/hexagon/cpu.c
index 658ca4ff783aa952c12b074761a9c076b43468a5..807037c586248004c047a47c332d173ed9da6a6b 100644 (file)
--- a/target/hexagon/cpu.c
+++ b/target/hexagon/cpu.c
@@ -86,7 +86,7 @@ static target_ulong adjust_stack_ptrs(CPUHexagonState *env, target_ulong addr)
     return addr;
 }
 
-/* HEX_REG_P3_0 (aka C4) is an alias for the predicate registers */
+/* HEX_REG_P3_0_ALIASED (aka C4) is an alias for the predicate registers */
 static target_ulong read_p3_0(CPUHexagonState *env)
 {
     int32_t control_reg = 0;
@@ -102,7 +102,7 @@ static void print_reg(FILE *f, CPUHexagonState *env, int regnum)
 {
     target_ulong value;
 
-    if (regnum == HEX_REG_P3_0) {
+    if (regnum == HEX_REG_P3_0_ALIASED) {
         value = read_p3_0(env);
     } else {
         value = regnum < 32 ? adjust_stack_ptrs(env, env->gpr[regnum])
@@ -198,7 +198,7 @@ static void hexagon_dump(CPUHexagonState *env, FILE *f, int flags)
     print_reg(f, env, HEX_REG_M0);
     print_reg(f, env, HEX_REG_M1);
     print_reg(f, env, HEX_REG_USR);
-    print_reg(f, env, HEX_REG_P3_0);
+    print_reg(f, env, HEX_REG_P3_0_ALIASED);
     print_reg(f, env, HEX_REG_GP);
     print_reg(f, env, HEX_REG_UGP);
     print_reg(f, env, HEX_REG_PC);

diff --git a/target/hexagon/genptr.c b/target/hexagon/genptr.c
index 6cf2e0ed431fd143b471d7ec9368e9bed5ddc3eb..66a968c88429dd86e2aafe8ef9b24c6b52d02c14 100644 (file)
--- a/target/hexagon/genptr.c
+++ b/target/hexagon/genptr.c
@@ -163,7 +163,7 @@ static inline void gen_read_p3_0(TCGv control_reg)
 
 /*
  * Certain control registers require special handling on read
- *     HEX_REG_P3_0          aliased to the predicate registers
+ *     HEX_REG_P3_0_ALIASED  aliased to the predicate registers
  *                           -> concat the 4 predicate registers together
  *     HEX_REG_PC            actual value stored in DisasContext
  *                           -> assign from ctx->base.pc_next
@@ -173,7 +173,7 @@ static inline void gen_read_p3_0(TCGv control_reg)
 static inline void gen_read_ctrl_reg(DisasContext *ctx, const int reg_num,
                                      TCGv dest)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         gen_read_p3_0(dest);
     } else if (reg_num == HEX_REG_PC) {
         tcg_gen_movi_tl(dest, ctx->base.pc_next);
@@ -194,7 +194,7 @@ static inline void gen_read_ctrl_reg(DisasContext *ctx, const int reg_num,
 static inline void gen_read_ctrl_reg_pair(DisasContext *ctx, const int reg_num,
                                           TCGv_i64 dest)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         TCGv p3_0 = tcg_temp_new();
         gen_read_p3_0(p3_0);
         tcg_gen_concat_i32_i64(dest, p3_0, hex_gpr[reg_num + 1]);
@@ -238,7 +238,7 @@ static void gen_write_p3_0(DisasContext *ctx, TCGv control_reg)
 
 /*
  * Certain control registers require special handling on write
- *     HEX_REG_P3_0          aliased to the predicate registers
+ *     HEX_REG_P3_0_ALIASED  aliased to the predicate registers
  *                           -> break the value across 4 predicate registers
  *     HEX_REG_QEMU_*_CNT    changes in current TB in DisasContext
  *                            -> clear the changes
@@ -246,7 +246,7 @@ static void gen_write_p3_0(DisasContext *ctx, TCGv control_reg)
 static inline void gen_write_ctrl_reg(DisasContext *ctx, int reg_num,
                                       TCGv val)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         gen_write_p3_0(ctx, val);
     } else {
         gen_log_reg_write(reg_num, val);
@@ -266,7 +266,7 @@ static inline void gen_write_ctrl_reg(DisasContext *ctx, int reg_num,
 static inline void gen_write_ctrl_reg_pair(DisasContext *ctx, int reg_num,
                                            TCGv_i64 val)
 {
-    if (reg_num == HEX_REG_P3_0) {
+    if (reg_num == HEX_REG_P3_0_ALIASED) {
         TCGv val32 = tcg_temp_new();
         tcg_gen_extrl_i64_i32(val32, val);
         gen_write_p3_0(ctx, val32);

diff --git a/target/hexagon/hex_regs.h b/target/hexagon/hex_regs.h
index a63c2c0fd548e833409d10bd436fe2c876fbb449..bddfc28021c600ab59a5fae908e8f1715eba4c79 100644 (file)
--- a/target/hexagon/hex_regs.h
+++ b/target/hexagon/hex_regs.h
@@ -58,7 +58,7 @@ enum {
     HEX_REG_LC0              = 33,
     HEX_REG_SA1              = 34,
     HEX_REG_LC1              = 35,
-    HEX_REG_P3_0             = 36,
+    HEX_REG_P3_0_ALIASED     = 36,
     HEX_REG_M0               = 38,
     HEX_REG_M1               = 39,
     HEX_REG_USR              = 40,