Use explicit casts for ext16u opcodes, and allow truncation
to happen with the store for st16 opcodes, and with the call
for bswap16 opcodes.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/tci.c | 28 +++++++---------------------
 1 file changed, 7 insertions(+), 21 deletions(-)

diff --git a/tcg/tci.c b/tcg/tci.c
index 7325c8bfd0..2440da1746 100644
--- a/tcg/tci.c
+++ b/tcg/tci.c
@@ -71,11 +71,6 @@ static int32_t tci_read_reg32s(const tcg_target_ulong *regs, TCGReg index)
 }
 #endif
 
-static uint16_t tci_read_reg16(const tcg_target_ulong *regs, TCGReg index)
-{
-    return (uint16_t)tci_read_reg(regs, index);
-}
-
 static uint32_t tci_read_reg32(const tcg_target_ulong *regs, TCGReg index)
 {
     return (uint32_t)tci_read_reg(regs, index);
@@ -157,15 +152,6 @@ tci_read_r(const tcg_target_ulong *regs, const uint8_t **tb_ptr)
     return value;
 }
 
-/* Read indexed register (16 bit) from bytecode. */
-static uint16_t tci_read_r16(const tcg_target_ulong *regs,
-                             const uint8_t **tb_ptr)
-{
-    uint16_t value = tci_read_reg16(regs, **tb_ptr);
-    *tb_ptr += 1;
-    return value;
-}
-
 #if TCG_TARGET_HAS_ext16s_i32 || TCG_TARGET_HAS_ext16s_i64
 /* Read indexed register (16 bit signed) from bytecode. */
 static int16_t tci_read_r16s(const tcg_target_ulong *regs,
@@ -509,7 +495,7 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
             *(uint8_t *)(t1 + t2) = t0;
             break;
         CASE_32_64(st16)
-            t0 = tci_read_r16(regs, &tb_ptr);
+            t0 = tci_read_r(regs, &tb_ptr);
             t1 = tci_read_r(regs, &tb_ptr);
             t2 = tci_read_s32(&tb_ptr);
             *(uint16_t *)(t1 + t2) = t0;
@@ -699,14 +685,14 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
 #if TCG_TARGET_HAS_ext16u_i32
         case INDEX_op_ext16u_i32:
             t0 = *tb_ptr++;
-            t1 = tci_read_r16(regs, &tb_ptr);
-            tci_write_reg(regs, t0, t1);
+            t1 = tci_read_r(regs, &tb_ptr);
+            tci_write_reg(regs, t0, (uint16_t)t1);
             break;
 #endif
 #if TCG_TARGET_HAS_bswap16_i32
         case INDEX_op_bswap16_i32:
             t0 = *tb_ptr++;
-            t1 = tci_read_r16(regs, &tb_ptr);
+            t1 = tci_read_r(regs, &tb_ptr);
             tci_write_reg(regs, t0, bswap16(t1));
             break;
 #endif
@@ -907,8 +893,8 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
 #if TCG_TARGET_HAS_ext16u_i64
         case INDEX_op_ext16u_i64:
             t0 = *tb_ptr++;
-            t1 = tci_read_r16(regs, &tb_ptr);
-            tci_write_reg(regs, t0, t1);
+            t1 = tci_read_r(regs, &tb_ptr);
+            tci_write_reg(regs, t0, (uint16_t)t1);
             break;
 #endif
 #if TCG_TARGET_HAS_ext32s_i64
@@ -930,7 +916,7 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
 #if TCG_TARGET_HAS_bswap16_i64
         case INDEX_op_bswap16_i64:
             t0 = *tb_ptr++;
-            t1 = tci_read_r16(regs, &tb_ptr);
+            t1 = tci_read_r(regs, &tb_ptr);
             tci_write_reg(regs, t0, bswap16(t1));
             break;
 #endif
-- 
2.25.1

On 2/17/21 9:19 PM, Richard Henderson wrote:
> Use explicit casts for ext16u opcodes, and allow truncation
> to happen with the store for st16 opcodes, and with the call
> for bswap16 opcodes.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tcg/tci.c | 28 +++++++---------------------
>  1 file changed, 7 insertions(+), 21 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>