Hi,
On 15/10/24 11:16, Paolo Bonzini wrote:
The gen_cmpxchg8b and gen_cmpxchg16b functions even have the correct
prototype already; the only thing that needs to be done is removing the
gen_lea_modrm() call.
This moves the last LOCK-enabled instructions to the new decoder. It is
now possible to assume that gen_multi0F is called only after checking
that PREFIX_LOCK was not specified.
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
target/i386/tcg/decode-new.h | 2 +
target/i386/tcg/translate.c | 121 +------------------------------
target/i386/tcg/decode-new.c.inc | 34 ++++++---
target/i386/tcg/emit.c.inc | 96 ++++++++++++++++++++++++
4 files changed, 124 insertions(+), 129 deletions(-)
+static void gen_CMPXCHG8B(DisasContext *s, X86DecodedInsn *decode)
+{
+ TCGv_i64 cmp, val, old;
+ TCGv Z;
+
+ cmp = tcg_temp_new_i64();
+ val = tcg_temp_new_i64();
+ old = tcg_temp_new_i64();
+
+ /* Construct the comparison values from the register pair. */
+ tcg_gen_concat_tl_i64(cmp, cpu_regs[R_EAX], cpu_regs[R_EDX]);
+ tcg_gen_concat_tl_i64(val, cpu_regs[R_EBX], cpu_regs[R_ECX]);
+
+ /* Only require atomic with LOCK; non-parallel handled in generator. */
+ if (s->prefix & PREFIX_LOCK) {
+ tcg_gen_atomic_cmpxchg_i64(old, s->A0, cmp, val, s->mem_index,
MO_TEUQ);
+ } else {
+ tcg_gen_nonatomic_cmpxchg_i64(old, s->A0, cmp, val,
+ s->mem_index, MO_TEUQ);
+ }
+
+ /* Set tmp0 to match the required value of Z. */
+ tcg_gen_setcond_i64(TCG_COND_EQ, cmp, old, cmp);
+ Z = tcg_temp_new();
+ tcg_gen_trunc_i64_tl(Z, cmp);
+
+ /*
+ * Extract the result values for the register pair.
+ * For 32-bit, we may do this unconditionally, because on success (Z=1),
+ * the old value matches the previous value in EDX:EAX. For x86_64,
+ * the store must be conditional, because we must leave the source
+ * registers unchanged on success, and zero-extend the writeback
+ * on failure (Z=0).
+ */
+ if (TARGET_LONG_BITS == 32) {
+ tcg_gen_extr_i64_tl(cpu_regs[R_EAX], cpu_regs[R_EDX], old);
+ } else {
+ TCGv zero = tcg_constant_tl(0);
+
+ tcg_gen_extr_i64_tl(s->T0, s->T1, old);
+ tcg_gen_movcond_tl(TCG_COND_EQ, cpu_regs[R_EAX], Z, zero,
+ s->T0, cpu_regs[R_EAX]);
+ tcg_gen_movcond_tl(TCG_COND_EQ, cpu_regs[R_EDX], Z, zero,
+ s->T1, cpu_regs[R_EDX]);
+ }
+
+ /* Update Z. */
+ gen_compute_eflags(s);
+ tcg_gen_deposit_tl(cpu_cc_src, cpu_cc_src, Z, ctz32(CC_Z), 1);
+}
On s390x the cdrom-test generates:
tcg/s390x/tcg-target.c.inc:1284:tgen_cmp2: code should not be reached
