diff options
| author | Joseph Myers <joseph@codesourcery.com> | 2020-05-13 23:49:27 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-06-10 12:10:24 -0400 |
| commit | 80b4008c805ebcfd4c0d302ac31c1689e34571e0 (patch) | |
| tree | 1b9d77a23eb27cbd12dd9f1b8fe201b2c9486e33 /target | |
| parent | 5579b524b0d2e4b310157c0b7985d35c24238120 (diff) | |
| download | qemu-80b4008c805ebcfd4c0d302ac31c1689e34571e0.zip qemu-80b4008c805ebcfd4c0d302ac31c1689e34571e0.tar.gz qemu-80b4008c805ebcfd4c0d302ac31c1689e34571e0.tar.bz2 | |
target/i386: fix floating-point load-constant rounding
The implementations of the fldl2t, fldl2e, fldpi, fldlg2 and fldln2
instructions load fixed constants independent of the rounding mode.
Fix them to load a value correctly rounded for the current rounding
mode (but always rounded to 64-bit precision independent of the
precision control, and without setting "inexact") as specified.
Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <alpine.DEB.2.21.2005132348310.11687@digraph.polyomino.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'target')
| -rw-r--r-- | target/i386/fpu_helper.c | 54 |
1 files changed, 49 insertions, 5 deletions
diff --git a/target/i386/fpu_helper.c b/target/i386/fpu_helper.c index 4d14c1c..f0b9cb5 100644 --- a/target/i386/fpu_helper.c +++ b/target/i386/fpu_helper.c @@ -59,8 +59,13 @@ #define FPUC_EM 0x3f #define floatx80_lg2 make_floatx80(0x3ffd, 0x9a209a84fbcff799LL) +#define floatx80_lg2_d make_floatx80(0x3ffd, 0x9a209a84fbcff798LL) #define floatx80_l2e make_floatx80(0x3fff, 0xb8aa3b295c17f0bcLL) +#define floatx80_l2e_d make_floatx80(0x3fff, 0xb8aa3b295c17f0bbLL) #define floatx80_l2t make_floatx80(0x4000, 0xd49a784bcd1b8afeLL) +#define floatx80_l2t_u make_floatx80(0x4000, 0xd49a784bcd1b8affLL) +#define floatx80_ln2_d make_floatx80(0x3ffe, 0xb17217f7d1cf79abLL) +#define floatx80_pi_d make_floatx80(0x4000, 0xc90fdaa22168c234LL) #if !defined(CONFIG_USER_ONLY) static qemu_irq ferr_irq; @@ -544,27 +549,66 @@ void helper_fld1_ST0(CPUX86State *env) void helper_fldl2t_ST0(CPUX86State *env) { - ST0 = floatx80_l2t; + switch (env->fpuc & FPU_RC_MASK) { + case FPU_RC_UP: + ST0 = floatx80_l2t_u; + break; + default: + ST0 = floatx80_l2t; + break; + } } void helper_fldl2e_ST0(CPUX86State *env) { - ST0 = floatx80_l2e; + switch (env->fpuc & FPU_RC_MASK) { + case FPU_RC_DOWN: + case FPU_RC_CHOP: + ST0 = floatx80_l2e_d; + break; + default: + ST0 = floatx80_l2e; + break; + } } void helper_fldpi_ST0(CPUX86State *env) { - ST0 = floatx80_pi; + switch (env->fpuc & FPU_RC_MASK) { + case FPU_RC_DOWN: + case FPU_RC_CHOP: + ST0 = floatx80_pi_d; + break; + default: + ST0 = floatx80_pi; + break; + } } void helper_fldlg2_ST0(CPUX86State *env) { - ST0 = floatx80_lg2; + switch (env->fpuc & FPU_RC_MASK) { + case FPU_RC_DOWN: + case FPU_RC_CHOP: + ST0 = floatx80_lg2_d; + break; + default: + ST0 = floatx80_lg2; + break; + } } void helper_fldln2_ST0(CPUX86State *env) { - ST0 = floatx80_ln2; + switch (env->fpuc & FPU_RC_MASK) { + case FPU_RC_DOWN: + case FPU_RC_CHOP: + ST0 = floatx80_ln2_d; + break; + default: + ST0 = floatx80_ln2; + break; + } } void helper_fldz_ST0(CPUX86State *env) |