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tcg-i386: Introduce limited deposit support

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x86 cannot provide an optimized generic deposit implementation. But at
least for a few special cases, namely for writing bits 0..7, 8..15, and
0..15, versions using only a single instruction are feasible.
Introducing such limited support improves emulating 16-bit x86 code on
x86, but also rarer cases where 32-bit or 64-bit code accesses bytes or
words.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Jan Kiszka 2011-09-29 18:52:11 +02:00 • committed by Blue Swirl
parent 7e17a21706
commit a4773324b4
4 changed files with 40 additions and 4 deletions
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4
tcg/tcg-op.h
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@ -2045,7 +2045,7 @@ static inline void tcg_gen_deposit_i32(TCGv_i32 ret, TCGv_i32 arg1,
TCGv_i32 arg2, unsigned int ofs,
unsigned int len)
{
if (TCG_TARGET_HAS_deposit_i32) {
if (TCG_TARGET_HAS_deposit_i32 && TCG_TARGET_deposit_i32_valid(ofs, len)) {
tcg_gen_op5ii_i32(INDEX_op_deposit_i32, ret, arg1, arg2, ofs, len);
} else {
uint32_t mask = (1u << len) - 1;
@ -2064,7 +2064,7 @@ static inline void tcg_gen_deposit_i64(TCGv_i64 ret, TCGv_i64 arg1,
TCGv_i64 arg2, unsigned int ofs,
unsigned int len)
{
if (TCG_TARGET_HAS_deposit_i64) {
if (TCG_TARGET_HAS_deposit_i64 && TCG_TARGET_deposit_i64_valid(ofs, len)) {
tcg_gen_op5ii_i64(INDEX_op_deposit_i64, ret, arg1, arg2, ofs, len);
} else {
uint64_t mask = (1ull << len) - 1;