motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-07 09:43:56 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

tcg-i386: Perform cmov detection at runtime for 32-bit.

Browse source 
Existing compile-time detection is spotty at best.  Convert
it all to runtime detection instead.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Richard Henderson 2012-12-28 14:17:02 -08:00 • committed by Blue Swirl
parent afcb92beac
commit 76a347e1cd
3 changed files with 49 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

31
tcg/i386/tcg-target.c
View file

@ -97,6 +97,18 @@ static const int tcg_target_call_oarg_regs[] = {
# define TCG_REG_L1 TCG_REG_EDX
#endif
/* For 32-bit, we are going to attempt to determine at runtime whether cmov
is available. However, the host compiler must supply <cpuid.h>, as we're
not going to go so far as our own inline assembly. */
#if TCG_TARGET_REG_BITS == 64
# define have_cmov 1
#elif defined(CONFIG_CPUID_H)
#include <cpuid.h>
static bool have_cmov;
#else
# define have_cmov 0
#endif
static uint8_t *tb_ret_addr;
static void patch_reloc(uint8_t *code_ptr, int type,
@ -943,7 +955,14 @@ static void tcg_out_movcond32(TCGContext *s, TCGCond cond, TCGArg dest,
TCGArg v1)
{
tcg_out_cmp(s, c1, c2, const_c2, 0);
tcg_out_modrm(s, OPC_CMOVCC | tcg_cond_to_jcc[cond], dest, v1);
if (have_cmov) {
tcg_out_modrm(s, OPC_CMOVCC | tcg_cond_to_jcc[cond], dest, v1);
} else {
int over = gen_new_label();
tcg_out_jxx(s, tcg_cond_to_jcc[tcg_invert_cond(cond)], over, 1);
tcg_out_mov(s, TCG_TYPE_I32, dest, v1);
tcg_out_label(s, over, s->code_ptr);
}
}
#if TCG_TARGET_REG_BITS == 64
@ -2243,6 +2262,16 @@ static void tcg_target_qemu_prologue(TCGContext *s)
static void tcg_target_init(TCGContext *s)
{
/* For 32-bit, 99% certainty that we're running on hardware that supports
cmov, but we still need to check. In case cmov is not available, we'll
use a small forward branch. */
#ifndef have_cmov
{
unsigned a, b, c, d;
have_cmov = (__get_cpuid(1, &a, &b, &c, &d) && (d & bit_CMOV));
}
#endif
#if !defined(CONFIG_USER_ONLY)
/* fail safe */
if ((1 << CPU_TLB_ENTRY_BITS) != sizeof(CPUTLBEntry))