From e0c1476d5d7c450b1b16a40364cea4e91237ea93 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Fri, 10 Nov 2023 16:41:19 -0700 Subject: [PATCH] libgcc/m68k: Fixes for soft float Check for non-zero denorm in __adddf3. Need to check both the upper and lower 32-bit chunks of a 64-bit float for a non-zero value when checking to see if the value is -0. Fix __addsf3 when the sum exponent is exactly 0xff to ensure that produces infinity and not nan. Handle converting NaN/inf values between formats. Handle underflow and overflow when truncating. Write a replacement for __fixxfsi so that it does not raise extra exceptions during an extra conversion from long double to double. libgcc/ * config/m68k/lb1sf68.S (__adddf3): Properly check for non-zero denorm. (__divdf3): Restore sign bit properly. (__addsf3): Correct exponent check. * config/m68k/fpgnulib.c (EXPMASK): Define. (__extendsfdf2): Handle Inf and NaN properly. (__truncdfsf2): Handle underflow and overflow correctly. (__extenddfxf2): Handle underflow, denorms, Inf and NaN correctly. (__truncxfdf2): Handle underflow and denorms correctly. (__fixxfsi): Reimplement. --- libgcc/config/m68k/fpgnulib.c | 161 ++++++++++++++++++++++++++++++++++-------- libgcc/config/m68k/lb1sf68.S | 7 +- 2 files changed, 134 insertions(+), 34 deletions(-) (limited to 'libgcc/config') diff --git a/libgcc/config/m68k/fpgnulib.c b/libgcc/config/m68k/fpgnulib.c index d5c3411..986750e 100644 --- a/libgcc/config/m68k/fpgnulib.c +++ b/libgcc/config/m68k/fpgnulib.c @@ -54,6 +54,7 @@ #define SIGNBIT 0x80000000L #define HIDDEN (1L << 23L) #define SIGN(fp) ((fp) & SIGNBIT) +#define EXPMASK 0xFFL #define EXP(fp) (((fp) >> 23L) & 0xFF) #define MANT(fp) (((fp) & 0x7FFFFFL) | HIDDEN) #define PACK(s,e,m) ((s) | ((e) << 23L) | (m)) @@ -262,6 +263,9 @@ __extendsfdf2 (float a1) mant &= ~HIDDEN; } exp = exp - EXCESS + EXCESSD; + /* Handle inf and NaN */ + if (exp == EXPMASK - EXCESS + EXCESSD) + exp = EXPDMASK; dl.l.upper |= exp << 20; dl.l.upper |= mant >> 3; dl.l.lower = mant << 29; @@ -295,40 +299,52 @@ __truncdfsf2 (double a1) /* shift double mantissa 6 bits so we can round */ sticky |= mant & ((1 << 6) - 1); mant >>= 6; - - /* Check for underflow and denormals. */ - if (exp <= 0) + if (exp == EXPDMASK - EXCESSD + EXCESS) + { + exp = EXPMASK; + mant = mant >> 1 | (mant & 1) | !!sticky; + } + else { - if (exp < -24) + /* Check for underflow and denormals. */ + if (exp <= 0) { - sticky |= mant; - mant = 0; + if (exp < -24) + { + sticky |= mant; + mant = 0; + } + else + { + sticky |= mant & ((1 << (1 - exp)) - 1); + mant >>= 1 - exp; + } + exp = 0; } - else + + /* now round */ + shift = 1; + if ((mant & 1) && (sticky || (mant & 2))) { - sticky |= mant & ((1 << (1 - exp)) - 1); - mant >>= 1 - exp; - } - exp = 0; - } - - /* now round */ - shift = 1; - if ((mant & 1) && (sticky || (mant & 2))) - { - int rounding = exp ? 2 : 1; + int rounding = exp ? 2 : 1; - mant += 1; + mant += 1; - /* did the round overflow? */ - if (mant >= (HIDDEN << rounding)) + /* did the round overflow? */ + if (mant >= (HIDDEN << rounding)) + { + exp++; + shift = rounding; + } + } + /* shift down */ + mant >>= shift; + if (exp >= EXPMASK) { - exp++; - shift = rounding; + exp = EXPMASK; + mant = 0; } } - /* shift down */ - mant >>= shift; mant &= ~HIDDEN; @@ -433,6 +449,30 @@ __extenddfxf2 (double d) } exp = EXPD (dl) - EXCESSD + EXCESSX; + /* Check for underflow and denormals. */ + if (exp < 0) + { + if (exp < -53) + { + ldl.l.middle = 0; + ldl.l.lower = 0; + } + else if (exp < -30) + { + ldl.l.lower = (ldl.l.middle & MANTXMASK) >> ((1 - exp) - 32); + ldl.l.middle &= ~MANTXMASK; + } + else + { + ldl.l.lower >>= 1 - exp; + ldl.l.lower |= (ldl.l.middle & MANTXMASK) << (32 - (1 - exp)); + ldl.l.middle = (ldl.l.middle & ~MANTXMASK) | (ldl.l.middle & MANTXMASK >> (1 - exp)); + } + exp = 0; + } + /* Handle inf and NaN */ + if (exp == EXPDMASK - EXCESSD + EXCESSX) + exp = EXPXMASK; ldl.l.upper |= exp << 16; ldl.l.middle = HIDDENX; /* 31-20: # mantissa bits in ldl.l.middle - # mantissa bits in dl.l.upper */ @@ -465,9 +505,38 @@ __truncxfdf2 (long double ld) } exp = EXPX (ldl) - EXCESSX + EXCESSD; - /* ??? quick and dirty: keep `exp' sane */ - if (exp >= EXPDMASK) - exp = EXPDMASK - 1; + /* Check for underflow and denormals. */ + if (exp <= 0) + { + if (exp < -53) + { + ldl.l.middle = 0; + ldl.l.lower = 0; + } + else if (exp < -30) + { + ldl.l.lower = (ldl.l.middle & MANTXMASK) >> ((1 - exp) - 32); + ldl.l.middle &= ~MANTXMASK; + } + else + { + ldl.l.lower >>= 1 - exp; + ldl.l.lower |= (ldl.l.middle & MANTXMASK) << (32 - (1 - exp)); + ldl.l.middle = (ldl.l.middle & ~MANTXMASK) | (ldl.l.middle & MANTXMASK >> (1 - exp)); + } + exp = 0; + } + else if (exp == EXPXMASK - EXCESSX + EXCESSD) + { + exp = EXPDMASK; + ldl.l.middle |= ldl.l.lower; + } + else if (exp >= EXPDMASK) + { + exp = EXPDMASK; + ldl.l.middle = 0; + ldl.l.lower = 0; + } dl.l.upper |= exp << (32 - (EXPDBITS + 1)); /* +1-1: add one for sign bit, but take one off for explicit-integer-bit */ dl.l.upper |= (ldl.l.middle & MANTXMASK) >> (EXPDBITS + 1 - 1); @@ -512,10 +581,40 @@ __floatunsixf (unsigned long l) /* convert a long double to an int */ long -__fixxfsi (long double ld) +__fixxfsi (long double a) { - long foo = __fixdfsi ((double) ld); - return foo; + union long_double_long ldl; + long exp; + long l; + + ldl.ld = a; + + exp = EXPX (ldl); + if (exp == 0 && ldl.l.middle == 0 && ldl.l.lower == 0) + return 0; + + exp = exp - EXCESSX - 63; + + if (exp > 0) + { + /* Return largest integer. */ + return SIGNX (ldl) ? 0x80000000L : 0x7fffffffL; + } + + if (exp <= -64) + return 0; + + if (exp <= -32) + { + ldl.l.lower = ldl.l.middle >> (-exp - 32); + } + else if (exp < 0) + { + ldl.l.lower = ldl.l.lower >> -exp; + ldl.l.lower |= ldl.l.middle << (32 + exp); + } + + return SIGNX (ldl) ? -ldl.l.lower : ldl.l.lower; } /* The remaining provide crude math support by working in double precision. */ diff --git a/libgcc/config/m68k/lb1sf68.S b/libgcc/config/m68k/lb1sf68.S index 8ba85c5..736a9a7 100644 --- a/libgcc/config/m68k/lb1sf68.S +++ b/libgcc/config/m68k/lb1sf68.S @@ -1383,6 +1383,8 @@ Ladddf$a: bge 2f | movel d0,d0 | check for zero, since we don't ' bne Ladddf$ret | want to return -0 by mistake + movel d1,d1 | + bne Ladddf$ret | bclr IMM (31),d7 | bra Ladddf$ret | 2: @@ -2090,8 +2092,7 @@ Ldivdf$a$nf: | If a is INFINITY we have to check b cmpl d7,d2 | compare b with INFINITY bge Ld$inop | if b is NaN or INFINITY return NaN - tstl d3 | - bne Ld$inop | + movl a0,d7 | restore sign bit to d7 bra Ld$overflow | else return overflow | If a number is denormalized we put an exponent of 1 but do not put the @@ -2936,7 +2937,7 @@ Laddsf$4: #else cmpl IMM (0xff),d2 #endif - bhi 1f + bge 1f bclr IMM (FLT_MANT_DIG-1),d0 #ifndef __mcoldfire__ lslw IMM (7),d2 -- cgit v1.1