From 86c0cab11aabb0c2a5cc76825bc05dfe2b367412 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Tue, 3 Jul 2018 08:17:32 -0700 Subject: [PATCH] target/ppc: Use non-arithmetic conversions for fp load/store Memory operations have no side effects on fp state. The use of a "real" conversions between float64 and float32 would raise exceptions for SNaN and out-of-range inputs. Signed-off-by: Richard Henderson Signed-off-by: David Gibson --- target/ppc/fpu_helper.c | 61 ++++++++++++++++++++++++++++++-------- target/ppc/helper.h | 4 +-- target/ppc/translate/fp-impl.inc.c | 26 +++++++--------- 3 files changed, 61 insertions(+), 30 deletions(-) diff --git a/target/ppc/fpu_helper.c b/target/ppc/fpu_helper.c index 5af5241ab0..b9bb1b856e 100644 --- a/target/ppc/fpu_helper.c +++ b/target/ppc/fpu_helper.c @@ -47,24 +47,61 @@ static inline bool fp_exceptions_enabled(CPUPPCState *env) /*****************************************************************************/ /* Floating point operations helpers */ -uint64_t helper_float32_to_float64(CPUPPCState *env, uint32_t arg) + +/* + * This is the non-arithmatic conversion that happens e.g. on loads. + * In the Power ISA pseudocode, this is called DOUBLE. + */ +uint64_t helper_todouble(uint32_t arg) { - CPU_FloatU f; - CPU_DoubleU d; + uint32_t abs_arg = arg & 0x7fffffff; + uint64_t ret; - f.l = arg; - d.d = float32_to_float64(f.f, &env->fp_status); - return d.ll; + if (likely(abs_arg >= 0x00800000)) { + /* Normalized operand, or Inf, or NaN. */ + ret = (uint64_t)extract32(arg, 30, 2) << 62; + ret |= ((extract32(arg, 30, 1) ^ 1) * (uint64_t)7) << 59; + ret |= (uint64_t)extract32(arg, 0, 30) << 29; + } else { + /* Zero or Denormalized operand. */ + ret = (uint64_t)extract32(arg, 31, 1) << 63; + if (unlikely(abs_arg != 0)) { + /* Denormalized operand. */ + int shift = clz32(abs_arg) - 9; + int exp = -126 - shift + 1023; + ret |= (uint64_t)exp << 52; + ret |= abs_arg << (shift + 29); + } + } + return ret; } -uint32_t helper_float64_to_float32(CPUPPCState *env, uint64_t arg) +/* + * This is the non-arithmatic conversion that happens e.g. on stores. + * In the Power ISA pseudocode, this is called SINGLE. + */ +uint32_t helper_tosingle(uint64_t arg) { - CPU_FloatU f; - CPU_DoubleU d; + int exp = extract64(arg, 52, 11); + uint32_t ret; - d.ll = arg; - f.f = float64_to_float32(d.d, &env->fp_status); - return f.l; + if (likely(exp > 896)) { + /* No denormalization required (includes Inf, NaN). */ + ret = extract64(arg, 62, 2) << 30; + ret |= extract64(arg, 29, 30); + } else { + /* Zero or Denormal result. If the exponent is in bounds for + * a single-precision denormal result, extract the proper bits. + * If the input is not zero, and the exponent is out of bounds, + * then the result is undefined; this underflows to zero. + */ + ret = extract64(arg, 63, 1) << 31; + if (unlikely(exp >= 874)) { + /* Denormal result. */ + ret |= ((1ULL << 52) | extract64(arg, 0, 52)) >> (896 + 30 - exp); + } + } + return ret; } static inline int ppc_float32_get_unbiased_exp(float32 f) diff --git a/target/ppc/helper.h b/target/ppc/helper.h index 7ed72c2337..ef64248bc4 100644 --- a/target/ppc/helper.h +++ b/target/ppc/helper.h @@ -61,8 +61,8 @@ DEF_HELPER_2(compute_fprf_float64, void, env, i64) DEF_HELPER_3(store_fpscr, void, env, i64, i32) DEF_HELPER_2(fpscr_clrbit, void, env, i32) DEF_HELPER_2(fpscr_setbit, void, env, i32) -DEF_HELPER_2(float64_to_float32, i32, env, i64) -DEF_HELPER_2(float32_to_float64, i64, env, i32) +DEF_HELPER_FLAGS_1(todouble, TCG_CALL_NO_RWG_SE, i64, i32) +DEF_HELPER_FLAGS_1(tosingle, TCG_CALL_NO_RWG_SE, i32, i64) DEF_HELPER_4(fcmpo, void, env, i64, i64, i32) DEF_HELPER_4(fcmpu, void, env, i64, i64, i32) diff --git a/target/ppc/translate/fp-impl.inc.c b/target/ppc/translate/fp-impl.inc.c index 2fbd4d4f38..a6f522b85c 100644 --- a/target/ppc/translate/fp-impl.inc.c +++ b/target/ppc/translate/fp-impl.inc.c @@ -660,15 +660,12 @@ GEN_LDUF(name, ldop, op | 0x21, type); \ GEN_LDUXF(name, ldop, op | 0x01, type); \ GEN_LDXF(name, ldop, 0x17, op | 0x00, type) -static inline void gen_qemu_ld32fs(DisasContext *ctx, TCGv_i64 arg1, TCGv arg2) +static void gen_qemu_ld32fs(DisasContext *ctx, TCGv_i64 dest, TCGv addr) { - TCGv t0 = tcg_temp_new(); - TCGv_i32 t1 = tcg_temp_new_i32(); - gen_qemu_ld32u(ctx, t0, arg2); - tcg_gen_trunc_tl_i32(t1, t0); - tcg_temp_free(t0); - gen_helper_float32_to_float64(arg1, cpu_env, t1); - tcg_temp_free_i32(t1); + TCGv_i32 tmp = tcg_temp_new_i32(); + tcg_gen_qemu_ld_i32(tmp, addr, ctx->mem_idx, DEF_MEMOP(MO_UL)); + gen_helper_todouble(dest, tmp); + tcg_temp_free_i32(tmp); } /* lfd lfdu lfdux lfdx */ @@ -836,15 +833,12 @@ GEN_STUF(name, stop, op | 0x21, type); \ GEN_STUXF(name, stop, op | 0x01, type); \ GEN_STXF(name, stop, 0x17, op | 0x00, type) -static inline void gen_qemu_st32fs(DisasContext *ctx, TCGv_i64 arg1, TCGv arg2) +static void gen_qemu_st32fs(DisasContext *ctx, TCGv_i64 src, TCGv addr) { - TCGv_i32 t0 = tcg_temp_new_i32(); - TCGv t1 = tcg_temp_new(); - gen_helper_float64_to_float32(t0, cpu_env, arg1); - tcg_gen_extu_i32_tl(t1, t0); - tcg_temp_free_i32(t0); - gen_qemu_st32(ctx, t1, arg2); - tcg_temp_free(t1); + TCGv_i32 tmp = tcg_temp_new_i32(); + gen_helper_tosingle(tmp, src); + tcg_gen_qemu_st_i32(tmp, addr, ctx->mem_idx, DEF_MEMOP(MO_UL)); + tcg_temp_free_i32(tmp); } /* stfd stfdu stfdux stfdx */ -- 2.11.0