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Darwin long double bug fixes, switch on by default
- From: gkeating at geoffk5 dot apple dot com (Geoffrey Keating)
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 30 Jul 2004 18:38:19 -0700 (PDT)
- Subject: Darwin long double bug fixes, switch on by default
This adds to the Darwin long double support:
- Some correctness (Radar number 3549987)
- A specification, so you can tell what it means to be correct
- A testcase, so it stays that way
It also fixes a problem where there was no way to load a long double
into GPRs from a static variable (I think), and incidentally fixes a
number of other problems involving loading things into multiple GPRs
from a non-offsettable address.
The problem was that movdi_internal32 says that you can move between
'm' and 'r', not just 'o<>' and 'r'; it looked like it'd generate
better code to just implement the case, rather than get reload to fix
it up.
It also switches 128-bit long double on by default, now that it
works. Yay!
Bootstrapped & tested on powerpc-darwin.
--
- Geoffrey Keating <geoffk@apple.com>
===File ~/patches/gcc-longdoubledefault.patch===============
2004-07-30 Geoffrey Keating <geoffk@apple.com>
* config/rs6000/rs6000.c (legitimate_lo_sum_address_p): Permit
non-offsettable addresses even for DImode.
(rs6000_split_multireg_move): Cope with non-offsettable addresses
being moved into multiple GPRs.
* config/rs6000/rs6000.c (RS6000_DEFAULT_LONG_DOUBLE_SIZE): Default
to 64.
(rs6000_override_options): Use RS6000_DEFAULT_LONG_DOUBLE_SIZE.
* config/rs6000/darwin.h (RS6000_DEFAULT_LONG_DOUBLE_SIZE): Define
to 128.
* config/rs6000/darwin-ldouble.c (isless): New macro.
(inf): New macro.
(nonfinite): New macro.
(FPKINF): Delete.
(_xlqadd): Completely rewrite.
(_xlqmul): Correct overflow handling.
(_xlqdiv): Correct overflow handling.
* config/rs6000/darwin-ldouble-format: New file.
Index: testsuite/ChangeLog
2004-07-30 Geoffrey Keating <geoffk@apple.com>
* gcc.dg/darwin-longdouble.c: New file.
Index: config/rs6000/darwin-ldouble-format
===================================================================
RCS file: config/rs6000/darwin-ldouble-format
diff -N config/rs6000/darwin-ldouble-format
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ config/rs6000/darwin-ldouble-format 31 Jul 2004 01:27:04 -0000
@@ -0,0 +1,84 @@
+Long double format
+==================
+
+ Each long double is made up of two IEEE doubles. The value of the
+long double is the sum of the values of the two parts (except for
+-0.0). The most significant part is required to be the value of the
+long double rounded to the nearest double, as specified by IEEE. For
+Inf values, the least significant part is required to be one of +0.0
+or -0.0. No other requirements are made; so, for example, 1.0 may be
+represented as (1.0, +0.0) or (1.0, -0.0), and the low part of a NaN
+is don't-care.
+
+Classification
+--------------
+
+A long double can represent any value of the form
+ s * 2^e * sum(k=0...105: f_k * 2^(-k))
+where 's' is +1 or -1, 'e' is between 1022 and -968 inclusive, f_0 is
+1, and f_k for k>0 is 0 or 1. These are the 'normal' long doubles.
+
+A long double can also represent any value of the form
+ s * 2^-968 * sum(k=0...105: f_k * 2^(-k))
+where 's' is +1 or -1, f_0 is 0, and f_k for k>0 is 0 or 1. These are
+the 'subnormal' long doubles.
+
+There are four long doubles that represent zero, two that represent
++0.0 and two that represent -0.0. The sign of the high part is the
+sign of the long double, and the sign of the low part is ignored.
+
+Likewise, there are four long doubles that represent infinities, two
+for +Inf and two for -Inf.
+
+Each NaN, quiet or signalling, that can be represented as a 'double'
+can be represented as a 'long double'. In fact, there are 2^64
+equivalent representations for each one.
+
+There are certain other valid long doubles where both parts are
+nonzero but the low part represents a value which has a bit set below
+2^(e-105). These, together with the subnormal long doubles, make up
+the denormal long doubles.
+
+Many possible long double bit patterns are not valid long doubles.
+These do not represent any value.
+
+Limits
+------
+
+The maximum representable long double is 2^1024-2^918. The smallest
+*normal* positive long double is 2^-968. The smallest denormalised
+positive long double is 2^-1074 (this is the same as for 'double').
+
+Conversions
+-----------
+
+A double can be converted to a long double by adding a zero low part.
+
+A long double can be converted to a double by removing the low part.
+
+Comparisons
+-----------
+
+Two long doubles can be compared by comparing the high parts, and if
+those compare equal, comparing the low parts.
+
+Arithmetic
+----------
+
+The unary negate operation operates by negating the low and high parts.
+
+An absolute or absolute-negate operation must be done by comparing
+against zero and negating if necessary.
+
+Addition and subtraction are performed using library routines. They
+are not at present performed perfectly accurately, the result produced
+will be within 1ulp of the range generated by adding or subtracting
+1ulp from the input values, where a 'ulp' is 2^(e-106) given the
+exponent 'e'. In the presence of cancellation, this may be
+arbitrarily inaccurate. Subtraction is done by negation and addition.
+
+Multiplication is also performed using a library routine. Its result
+will be within 2ulp of the correct result.
+
+Division is also performed using a library routine. Its result will
+be within 3ulp of the correct result.
Index: config/rs6000/darwin-ldouble.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/darwin-ldouble.c,v
retrieving revision 1.7
diff -u -p -u -p -r1.7 darwin-ldouble.c
--- config/rs6000/darwin-ldouble.c 8 Jul 2004 21:16:17 -0000 1.7
+++ config/rs6000/darwin-ldouble.c 31 Jul 2004 01:27:04 -0000
@@ -51,9 +51,13 @@ Software Foundation, 59 Temple Place - S
#if !_SOFT_FLOAT && (defined (__MACH__) || defined (__powerpc64__))
#define fabs(x) __builtin_fabs(x)
+#define isless(x, y) __builtin_isless (x, y)
+#define inf() __builtin_inf()
#define unlikely(x) __builtin_expect ((x), 0)
+#define nonfinite(a) unlikely (! isless (fabs (a), inf ()))
+
/* All these routines actually take two long doubles as parameters,
but GCC currently generates poor code when a union is used to turn
a long double into a pair of doubles. */
@@ -69,66 +73,40 @@ typedef union
double dval[2];
} longDblUnion;
-static const double FPKINF = 1.0/0.0;
-
/* Add two 'long double' values and return the result. */
long double
-_xlqadd (double a, double b, double c, double d)
+_xlqadd (double a, double aa, double c, double cc)
{
- longDblUnion z;
- double t, tau, u, FPR_zero, FPR_PosInf;
-
- FPR_zero = 0.0;
- FPR_PosInf = FPKINF;
-
- if (unlikely (a != a) || unlikely (c != c))
- return a + c; /* NaN result. */
+ longDblUnion x;
+ double z, q, zz, xh;
- /* Ordered operands are arranged in order of their magnitudes. */
+ z = a + c;
- /* Switch inputs if |(c,d)| > |(a,b)|. */
- if (fabs (c) > fabs (a))
+ if (nonfinite (z))
{
- t = a;
- tau = b;
- a = c;
- b = d;
- c = t;
- d = tau;
+ z = cc + aa + c + a;
+ if (nonfinite (z))
+ return z;
+ x.dval[0] = z; /* Will always be DBL_MAX. */
+ zz = aa + cc;
+ if (fabs(a) > fabs(c))
+ x.dval[1] = a - z + c + zz;
+ else
+ x.dval[1] = c - z + a + zz;
}
-
- /* b <- second largest magnitude double. */
- if (fabs (c) > fabs (b))
+ else
{
- t = b;
- b = c;
- c = t;
- }
+ q = a - z;
+ zz = q + c + (a - (q + z)) + aa + cc;
+ xh = z + zz;
- /* Thanks to commutativity, sum is invariant w.r.t. the next
- conditional exchange. */
- tau = d + c;
+ if (nonfinite (xh))
+ return xh;
- /* Order the smallest magnitude doubles. */
- if (fabs (d) > fabs (c))
- {
- t = c;
- c = d;
- d = t;
+ x.dval[0] = xh;
+ x.dval[1] = z - xh + zz;
}
-
- t = (tau + b) + a; /* Sum values in ascending magnitude order. */
-
- /* Infinite or zero result. */
- if (unlikely (t == FPR_zero) || unlikely (fabs (t) == FPR_PosInf))
- return t;
-
- /* Usual case. */
- tau = (((a-t) + b) + c) + d;
- u = t + tau;
- z.dval[0] = u; /* Final fixup for long double result. */
- z.dval[1] = (t - u) + tau;
- return z.ldval;
+ return x.ldval;
}
long double
@@ -141,21 +119,17 @@ long double
_xlqmul (double a, double b, double c, double d)
{
longDblUnion z;
- double t, tau, u, v, w, FPR_zero, FPR_PosInf;
+ double t, tau, u, v, w;
- FPR_zero = 0.0;
- FPR_PosInf = FPKINF;
-
t = a * c; /* Highest order double term. */
- if (unlikely (t != t) || unlikely (t == FPR_zero)
- || unlikely (fabs (t) == FPR_PosInf))
+ if (unlikely (t == 0) /* Preserve -0. */
+ || nonfinite (t))
return t;
- /* Finite nonzero result requires summing of terms of two highest
- orders. */
+ /* Sum terms of two highest orders. */
- /* Use fused multiply-add to get low part of a * c. */
+ /* Use fused multiply-add to get low part of a * c. */
asm ("fmsub %0,%1,%2,%3" : "=f"(tau) : "f"(a), "f"(c), "f"(t));
v = a*d;
w = b*c;
@@ -163,6 +137,8 @@ _xlqmul (double a, double b, double c, d
u = t + tau;
/* Construct long double result. */
+ if (nonfinite (u))
+ return u;
z.dval[0] = u;
z.dval[1] = (t - u) + tau;
return z.ldval;
@@ -172,15 +148,12 @@ long double
_xlqdiv (double a, double b, double c, double d)
{
longDblUnion z;
- double s, sigma, t, tau, u, v, w, FPR_zero, FPR_PosInf;
-
- FPR_zero = 0.0;
- FPR_PosInf = FPKINF;
+ double s, sigma, t, tau, u, v, w;
t = a / c; /* highest order double term */
- if (unlikely (t != t) || unlikely (t == FPR_zero)
- || unlikely (fabs (t) == FPR_PosInf))
+ if (unlikely (t == 0) /* Preserve -0. */
+ || nonfinite (t))
return t;
/* Finite nonzero result requires corrections to the highest order term. */
@@ -197,6 +170,8 @@ _xlqdiv (double a, double b, double c, d
u = t + tau;
/* Construct long double result. */
+ if (nonfinite (u))
+ return u;
z.dval[0] = u;
z.dval[1] = (t - u) + tau;
return z.ldval;
Index: config/rs6000/darwin.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/darwin.h,v
retrieving revision 1.55
diff -u -p -u -p -r1.55 darwin.h
--- config/rs6000/darwin.h 28 Jul 2004 23:57:26 -0000 1.55
+++ config/rs6000/darwin.h 31 Jul 2004 01:27:04 -0000
@@ -68,7 +68,7 @@
/* The Darwin ABI always includes AltiVec, can't be (validly) turned
off. */
-#define SUBTARGET_OVERRIDE_OPTIONS \
+#define SUBTARGET_OVERRIDE_OPTIONS \
do { \
rs6000_altivec_abi = 1; \
rs6000_altivec_vrsave = 1; \
@@ -87,12 +87,19 @@ do { \
flag_pic = 2; \
} \
} \
-}while(0)
+} while(0)
+
+/* Darwin has 128-bit long double support in libc in 10.4 and later.
+ Default to 128-bit long doubles even on earlier platforms for ABI
+ consistency; arithmetic will work even if libc and libm support is
+ not available. */
+
+#define RS6000_DEFAULT_LONG_DOUBLE_SIZE 128
+
/* We want -fPIC by default, unless we're using -static to compile for
the kernel or some such. */
-
#define CC1_SPEC "\
%{gused: -g -feliminate-unused-debug-symbols %<gused }\
%{gfull: -g -fno-eliminate-unused-debug-symbols %<gfull }\
Index: config/rs6000/rs6000.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/rs6000.c,v
retrieving revision 1.673
diff -u -p -u -p -r1.673 rs6000.c
--- config/rs6000/rs6000.c 28 Jul 2004 12:13:13 -0000 1.673
+++ config/rs6000/rs6000.c 31 Jul 2004 01:27:04 -0000
@@ -1014,6 +1014,13 @@ rs6000_init_hard_regno_mode_ok (void)
rs6000_hard_regno_mode_ok_p[m][r] = true;
}
+/* If not otherwise specified by a target, make 'long double' equivalent to
+ 'double'. */
+
+#ifndef RS6000_DEFAULT_LONG_DOUBLE_SIZE
+#define RS6000_DEFAULT_LONG_DOUBLE_SIZE 64
+#endif
+
/* Override command line options. Mostly we process the processor
type and sometimes adjust other TARGET_ options. */
@@ -1220,7 +1227,7 @@ rs6000_override_options (const char *def
}
/* Set size of long double */
- rs6000_long_double_type_size = 64;
+ rs6000_long_double_type_size = RS6000_DEFAULT_LONG_DOUBLE_SIZE;
if (rs6000_long_double_size_string)
{
char *tail;
@@ -1293,7 +1300,7 @@ rs6000_override_options (const char *def
if (rs6000_isel_string == 0)
rs6000_isel = 0;
if (rs6000_long_double_size_string == 0)
- rs6000_long_double_type_size = 64;
+ rs6000_long_double_type_size = RS6000_DEFAULT_LONG_DOUBLE_SIZE;
}
rs6000_always_hint = (rs6000_cpu != PROCESSOR_POWER4
@@ -3161,8 +3168,7 @@ legitimate_lo_sum_address_p (enum machin
return false;
if (GET_MODE_NUNITS (mode) != 1)
return false;
- if (GET_MODE_BITSIZE (mode) > 32
- && !(TARGET_HARD_FLOAT && TARGET_FPRS && mode == DFmode))
+ if (GET_MODE_BITSIZE (mode) > 64)
return false;
return CONSTANT_P (x);
@@ -11054,7 +11060,7 @@ rs6000_split_multireg_move (rtx dst, rtx
int j = -1;
bool used_update = false;
- if (GET_CODE (src) == MEM && INT_REGNO_P (reg))
+ if (MEM_P (src) && INT_REGNO_P (reg))
{
rtx breg;
@@ -11071,6 +11077,15 @@ rs6000_split_multireg_move (rtx dst, rtx
: gen_adddi3 (breg, breg, delta_rtx));
src = gen_rtx_MEM (mode, breg);
}
+ else if (! offsettable_memref_p (src))
+ {
+ rtx newsrc, basereg;
+ basereg = gen_rtx_REG (Pmode, reg);
+ emit_insn (gen_rtx_SET (VOIDmode, basereg, XEXP (src, 0)));
+ newsrc = gen_rtx_MEM (GET_MODE (src), basereg);
+ MEM_COPY_ATTRIBUTES (newsrc, src);
+ src = newsrc;
+ }
/* We have now address involving an base register only.
If we use one of the registers to address memory,
@@ -11118,6 +11133,15 @@ rs6000_split_multireg_move (rtx dst, rtx
: gen_adddi3 (breg, breg, delta_rtx));
dst = gen_rtx_MEM (mode, breg);
}
+ else if (! offsettable_memref_p (dst))
+ {
+ rtx newdst, basereg;
+ basereg = gen_rtx_REG (Pmode, reg);
+ emit_insn (gen_rtx_SET (VOIDmode, basereg, XEXP (dst, 0)));
+ newdst = gen_rtx_MEM (GET_MODE (dst), basereg);
+ MEM_COPY_ATTRIBUTES (newdst, dst);
+ dst = newdst;
+ }
}
for (i = 0; i < nregs; i++)
Index: testsuite/gcc.dg/darwin-longdouble.c
===================================================================
RCS file: testsuite/gcc.dg/darwin-longdouble.c
diff -N testsuite/gcc.dg/darwin-longdouble.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gcc.dg/darwin-longdouble.c 31 Jul 2004 01:27:12 -0000
@@ -0,0 +1,117 @@
+/* { dg-do run { target powerpc*-*-darwin* } } */
+/* { dg-options "" } */
+/* No options so 'long long' can be used. */
+
+#include <stdio.h>
+
+typedef unsigned long long uint64_t;
+typedef uint64_t ldbits[2];
+
+union ldu
+{
+ ldbits lb;
+ long double ld;
+};
+
+static const struct {
+ ldbits a;
+ ldbits b;
+ ldbits result;
+} single_tests[] = {
+ /* Test of values that add to near +Inf. */
+ { { 0x7FEFFFFFFFFFFFFFLL, 0xFC88000000000000LL },
+ { 0x7C94000000000000LL, 0x0000000000000000LL },
+ { 0x7FEFFFFFFFFFFFFFLL, 0x7C80000000000000LL } },
+ { { 0x7FEFFFFFFFFFFFFFLL, 0x7C8FFFFFFFFFFFFFLL },
+ { 0x792FFFFFFFFFFFFFLL, 0x0000000000000000LL },
+ { 0x7FEFFFFFFFFFFFFFLL, 0x7C8FFFFFFFFFFFFFLL } },
+ { { 0x7FEFFFFFFFFFFFFFLL, 0x7C8FFFFFFFFFFFFFLL },
+ { 0x7930000000000000LL, 0xF5DFFFFFFFFFFFFFLL },
+ /* correct result is: { 0x7FEFFFFFFFFFFFFFLL, 0x7C8FFFFFFFFFFFFFLL } */
+ { 0x7FF0000000000000LL, 0x0000000000000000LL } },
+ /* Test of values that add to +Inf. */
+ { { 0x7FEFFFFFFFFFFFFFLL, 0x7C8FFFFFFFFFFFFFLL },
+ { 0x7930000000000000LL, 0x0000000000000000LL },
+ { 0x7FF0000000000000LL, 0x0000000000000000LL } },
+ /* Tests of Inf addition. */
+ { { 0x7FF0000000000000LL, 0x0000000000000000LL },
+ { 0x0000000000000000LL, 0x0000000000000000LL },
+ { 0x7FF0000000000000LL, 0x0000000000000000LL } },
+ { { 0x7FF0000000000000LL, 0x0000000000000000LL },
+ { 0x7FF0000000000000LL, 0x0000000000000000LL },
+ { 0x7FF0000000000000LL, 0x0000000000000000LL } },
+ /* Test of Inf addition producing NaN. */
+ { { 0x7FF0000000000000LL, 0x0000000000000000LL },
+ { 0xFFF0000000000000LL, 0x0000000000000000LL },
+ { 0x7FF8000000000000LL, 0x0000000000000000LL } },
+ /* Tests of NaN addition. */
+ { { 0x7FF8000000000000LL, 0x0000000000000000LL },
+ { 0x0000000000000000LL, 0x0000000000000000LL },
+ { 0x7FF8000000000000LL, 0x7FF8000000000000LL } },
+ { { 0x7FF8000000000000LL, 0x0000000000000000LL },
+ { 0x7FF0000000000000LL, 0x0000000000000000LL },
+ { 0x7FF8000000000000LL, 0x7FF8000000000000LL } },
+ /* Addition of positive integers, with interesting rounding properties. */
+ { { 0x4690000000000000LL, 0x4330000000000000LL },
+ { 0x4650000000000009LL, 0xC2FFFFFFFFFFFFF2LL },
+ /* correct result is: { 0x4691000000000001LL, 0xC32C000000000000LL } */
+ { 0x4691000000000001LL, 0xc32bfffffffffffeLL } },
+ { { 0x4690000000000000LL, 0x4330000000000000LL },
+ { 0x4650000000000008LL, 0x42F0000000000010LL },
+ { 0x4691000000000001LL, 0xC32E000000000000LL } },
+ { { 0x469FFFFFFFFFFFFFLL, 0x433FFFFFFFFFFFFFLL },
+ { 0x4340000000000000LL, 0x3FF0000000000000LL },
+ { 0x46A0000000000000LL, 0x0000000000000000LL } },
+ { { 0x469FFFFFFFFFFFFFLL, 0x433FFFFFFFFFFFFFLL },
+ { 0x4340000000000000LL, 0x0000000000000000LL },
+ { 0x46A0000000000000LL, 0xBFF0000000000000LL } },
+ /* Subtraction of integers, with cancellation. */
+ { { 0x4690000000000000LL, 0x4330000000000000LL },
+ { 0xC690000000000000LL, 0xC330000000000000LL },
+ { 0x0000000000000000LL, 0x0000000000000000LL } },
+ { { 0x4690000000000000LL, 0x4330000000000000LL },
+ { 0xC330000000000000LL, 0x0000000000000000LL },
+ { 0x4690000000000000LL, 0x0000000000000000LL } },
+ { { 0x4690000000000000LL, 0x4330000000000000LL },
+ { 0xC330000000000000LL, 0x3FA0000000000000LL },
+ { 0x4690000000000000LL, 0x3FA0000000000000LL } },
+ { { 0x4690000000000000LL, 0x4330000000000000LL },
+ { 0xC690000000000000LL, 0x3FA0000000000000LL },
+ /* correct result is: { 0x4330000000000000LL, 0x3FA0000000000000LL } */
+ { 0x4330000000000000LL, 0x0000000000000000LL } }
+};
+
+static int fail = 0;
+
+static void
+run_single_tests (void)
+{
+ size_t i;
+ for (i = 0; i < sizeof (single_tests) / sizeof (single_tests[0]); i++)
+ {
+ union ldu a, b, result, expected;
+ memcpy (a.lb, single_tests[i].a, sizeof (ldbits));
+ memcpy (b.lb, single_tests[i].b, sizeof (ldbits));
+ memcpy (expected.lb, single_tests[i].result, sizeof (ldbits));
+ result.ld = a.ld + b.ld;
+ if (memcmp (result.lb, expected.lb,
+ result.ld == result.ld ? sizeof (ldbits) : sizeof (double))
+ != 0)
+ {
+ printf ("FAIL: %016llx %016llx + %016llx %016llx\n",
+ a.lb[0], a.lb[1], b.lb[0], b.lb[1]);
+ printf (" = %016llx %016llx not %016llx %016llx\n",
+ result.lb[0], result.lb[1], expected.lb[0], expected.lb[1]);
+ fail = 1;
+ }
+ }
+}
+
+int main(void)
+{
+ run_single_tests();
+ if (fail)
+ abort ();
+ else
+ exit (0);
+}
============================================================