diff options
| author | Richard Henderson <rth@twiddle.net> | 2012-12-28 14:17:02 -0800 |
|---|---|---|
| committer | Blue Swirl <blauwirbel@gmail.com> | 2012-12-29 12:21:16 +0000 |
| commit | 76a347e1cd0c2d6959461c89dda15ef5c4140da6 (patch) | |
| tree | 6f409224cb177c5aaba1871e0c82b9b179329913 /tcg/i386 | |
| parent | afcb92beac9e477e5ae5c36bf38830e225e2235f (diff) | |
tcg-i386: Perform cmov detection at runtime for 32-bit.
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>
Diffstat (limited to 'tcg/i386')
| -rw-r--r-- | tcg/i386/tcg-target.c | 31 | ||||
| -rw-r--r-- | tcg/i386/tcg-target.h | 5 |
2 files changed, 30 insertions, 6 deletions
diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c index ae8274652a..e0838748a9 100644 --- a/tcg/i386/tcg-target.c +++ b/tcg/i386/tcg-target.c @@ -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)) diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h index 5352ac0254..e63db9cfe9 100644 --- a/tcg/i386/tcg-target.h +++ b/tcg/i386/tcg-target.h @@ -91,12 +91,7 @@ typedef enum { #define TCG_TARGET_HAS_nand_i32 0 #define TCG_TARGET_HAS_nor_i32 0 #define TCG_TARGET_HAS_deposit_i32 1 -#if defined(__x86_64__) || defined(__i686__) -/* Use cmov only if the compiler is already doing so. */ #define TCG_TARGET_HAS_movcond_i32 1 -#else -#define TCG_TARGET_HAS_movcond_i32 0 -#endif #if TCG_TARGET_REG_BITS == 64 #define TCG_TARGET_HAS_div2_i64 1 |