diff options
Diffstat (limited to 'gcc/libgcc2.c')
| -rw-r--r-- | gcc/libgcc2.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/gcc/libgcc2.c b/gcc/libgcc2.c index ad0dc16fe11..fc2e1ac64b4 100644 --- a/gcc/libgcc2.c +++ b/gcc/libgcc2.c @@ -1021,6 +1021,25 @@ __floatdidf (u) #define WORD_SIZE (sizeof (SItype) * BITS_PER_UNIT) #define HIGH_HALFWORD_COEFF (((UDItype) 1) << (WORD_SIZE / 2)) #define HIGH_WORD_COEFF (((UDItype) 1) << WORD_SIZE) +#define DI_SIZE (sizeof (DItype) * BITS_PER_UNIT) +#if TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT +#define DF_SIZE 53 +#define SF_SIZE 24 +#else +#if TARGET_FLOAT_FORMAT == IBM_FLOAT_FORMAT +#define DF_SIZE 56 +#define SF_SIZE 24 +#else +#if TARGET_FLOAT_FORMAT == VAX_FLOAT_FORMAT +#define DF_SIZE 56 +#define SF_SIZE 24 +#else +#define DF_SIZE 0 +#define SF_SIZE 0 +#endif +#endif +#endif + SFtype __floatdisf (u) @@ -1035,6 +1054,22 @@ __floatdisf (u) if (u < 0) u = -u, negate = 1; + /* Protect against double-rounding error. + Represent any low-order bits, that might be truncated in DFmode, + by a bit that won't be lost. The bit can go in anywhere below the + rounding position of the SFmode. A fixed mask and bit position + handles all usual configurations. It doesn't handle the case + of 128-bit DImode, however. */ + if (DF_SIZE < DI_SIZE + && DF_SIZE > (DI_SIZE - DF_SIZE + SF_SIZE)) + { +#define REP_BIT ((USItype) 1 << (DI_SIZE - DF_SIZE)) + if (u >= ((UDItype) 1 << DF_SIZE)) + { + if ((USItype) u & (REP_BIT - 1)) + u |= REP_BIT; + } + } f = (USItype) (u >> WORD_SIZE); f *= HIGH_HALFWORD_COEFF; f *= HIGH_HALFWORD_COEFF; |