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authorMaciej W. Rozycki <macro@imgtec.com>2015-11-13 00:47:28 +0000
committerRalf Baechle <ralf@linux-mips.org>2016-01-20 00:39:20 +0100
commit90d53a91fbd0c5a0882c29fa4279a3d2d700c76d (patch)
treefa0deb99a2ffe52a7810c74bd332f3bbbbaaf053
parent198f70589e3c0f0f50da646152443787e959228f (diff)
downloadlinux-stericsson-90d53a91fbd0c5a0882c29fa4279a3d2d700c76d.tar.gz
MIPS: math-emu: Add IEEE Std 754-2008 NaN encoding emulation
Implement IEEE Std 754-2008 NaN encoding wired to the state of the FCSR.NAN2008 bit. Make the interpretation of the quiet bit in NaN data as follows: * in the legacy mode originally defined by the MIPS architecture the value of 1 denotes an sNaN whereas the value of 0 denotes a qNaN, * in the 2008 mode introduced with revision 5 of the MIPS architecture the value of 0 denotes an sNaN whereas the value of 1 denotes a qNaN, following the definition of the preferred NaN encoding introduced with IEEE Std 754-2008. In the 2008 mode, following the requirement of the said standard, quiet an sNaN where needed by setting the quiet bit to 1 and leaving all the NaN payload bits unchanged. Update format conversion operations according to the rules set by IEEE Std 754-2008 and the MIPS architecture. Specifically: * propagate NaN payload bits through conversions between floating-point formats such that as much information as possible is preserved and specifically a conversion from a narrower format to a wider format and then back to the original format does not change a qNaN payload in any way, * conversions from a floating-point to an integer format where the source is a NaN, infinity or a value that would convert to an integer outside the range of the result format produce, under the default exception handling, the respective values defined by the MIPS architecture. In full FPU emulation set the FIR.HAS2008 bit to 1, however do not make any further FCSR bits writable. Signed-off-by: Maciej W. Rozycki <macro@imgtec.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Matthew Fortune <Matthew.Fortune@imgtec.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/11477/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/kernel/cpu-probe.c2
-rw-r--r--arch/mips/math-emu/dp_tint.c9
-rw-r--r--arch/mips/math-emu/dp_tlong.c9
-rw-r--r--arch/mips/math-emu/ieee754.c6
-rw-r--r--arch/mips/math-emu/ieee754.h42
-rw-r--r--arch/mips/math-emu/ieee754dp.c12
-rw-r--r--arch/mips/math-emu/ieee754int.h12
-rw-r--r--arch/mips/math-emu/ieee754sp.c12
-rw-r--r--arch/mips/math-emu/sp_fdp.c13
-rw-r--r--arch/mips/math-emu/sp_tint.c9
-rw-r--r--arch/mips/math-emu/sp_tlong.c9
11 files changed, 93 insertions, 42 deletions
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 758b625d95e0..937e6534b8a0 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -113,6 +113,8 @@ static void cpu_set_nofpu_id(struct cpuinfo_mips *c)
if (c->isa_level & (MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
value |= MIPS_FPIR_F64 | MIPS_FPIR_L | MIPS_FPIR_W;
+ if (c->options & MIPS_CPU_NAN_2008)
+ value |= MIPS_FPIR_HAS2008;
c->fpu_id = value;
}
diff --git a/arch/mips/math-emu/dp_tint.c b/arch/mips/math-emu/dp_tint.c
index 6ffc336c530e..f3985617ce31 100644
--- a/arch/mips/math-emu/dp_tint.c
+++ b/arch/mips/math-emu/dp_tint.c
@@ -38,10 +38,13 @@ int ieee754dp_tint(union ieee754dp x)
switch (xc) {
case IEEE754_CLASS_SNAN:
case IEEE754_CLASS_QNAN:
- case IEEE754_CLASS_INF:
ieee754_setcx(IEEE754_INVALID_OPERATION);
return ieee754si_indef();
+ case IEEE754_CLASS_INF:
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754si_overflow(xs);
+
case IEEE754_CLASS_ZERO:
return 0;
@@ -53,7 +56,7 @@ int ieee754dp_tint(union ieee754dp x)
/* Set invalid. We will only use overflow for floating
point overflow */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754si_indef();
+ return ieee754si_overflow(xs);
}
/* oh gawd */
if (xe > DP_FBITS) {
@@ -93,7 +96,7 @@ int ieee754dp_tint(union ieee754dp x)
if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
/* This can happen after rounding */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754si_indef();
+ return ieee754si_overflow(xs);
}
if (round || sticky)
ieee754_setcx(IEEE754_INEXACT);
diff --git a/arch/mips/math-emu/dp_tlong.c b/arch/mips/math-emu/dp_tlong.c
index 9cdc145b75e0..748fa10ed4cf 100644
--- a/arch/mips/math-emu/dp_tlong.c
+++ b/arch/mips/math-emu/dp_tlong.c
@@ -38,10 +38,13 @@ s64 ieee754dp_tlong(union ieee754dp x)
switch (xc) {
case IEEE754_CLASS_SNAN:
case IEEE754_CLASS_QNAN:
- case IEEE754_CLASS_INF:
ieee754_setcx(IEEE754_INVALID_OPERATION);
return ieee754di_indef();
+ case IEEE754_CLASS_INF:
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754di_overflow(xs);
+
case IEEE754_CLASS_ZERO:
return 0;
@@ -56,7 +59,7 @@ s64 ieee754dp_tlong(union ieee754dp x)
/* Set invalid. We will only use overflow for floating
point overflow */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754di_indef();
+ return ieee754di_overflow(xs);
}
/* oh gawd */
if (xe > DP_FBITS) {
@@ -97,7 +100,7 @@ s64 ieee754dp_tlong(union ieee754dp x)
if ((xm >> 63) != 0) {
/* This can happen after rounding */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754di_indef();
+ return ieee754di_overflow(xs);
}
if (round || sticky)
ieee754_setcx(IEEE754_INEXACT);
diff --git a/arch/mips/math-emu/ieee754.c b/arch/mips/math-emu/ieee754.c
index 8e97acbbe22c..e16ae7b75dbb 100644
--- a/arch/mips/math-emu/ieee754.c
+++ b/arch/mips/math-emu/ieee754.c
@@ -59,7 +59,8 @@ const union ieee754dp __ieee754dp_spcvals[] = {
DPCNST(1, 3, 0x4000000000000ULL), /* - 10.0 */
DPCNST(0, DP_EMAX + 1, 0x0000000000000ULL), /* + infinity */
DPCNST(1, DP_EMAX + 1, 0x0000000000000ULL), /* - infinity */
- DPCNST(0, DP_EMAX + 1, 0x7FFFFFFFFFFFFULL), /* + indef quiet Nan */
+ DPCNST(0, DP_EMAX + 1, 0x7FFFFFFFFFFFFULL), /* + ind legacy qNaN */
+ DPCNST(0, DP_EMAX + 1, 0x8000000000000ULL), /* + indef 2008 qNaN */
DPCNST(0, DP_EMAX, 0xFFFFFFFFFFFFFULL), /* + max */
DPCNST(1, DP_EMAX, 0xFFFFFFFFFFFFFULL), /* - max */
DPCNST(0, DP_EMIN, 0x0000000000000ULL), /* + min normal */
@@ -82,7 +83,8 @@ const union ieee754sp __ieee754sp_spcvals[] = {
SPCNST(1, 3, 0x200000), /* - 10.0 */
SPCNST(0, SP_EMAX + 1, 0x000000), /* + infinity */
SPCNST(1, SP_EMAX + 1, 0x000000), /* - infinity */
- SPCNST(0, SP_EMAX + 1, 0x3FFFFF), /* + indef quiet Nan */
+ SPCNST(0, SP_EMAX + 1, 0x3FFFFF), /* + indef legacy quiet NaN */
+ SPCNST(0, SP_EMAX + 1, 0x400000), /* + indef 2008 quiet NaN */
SPCNST(0, SP_EMAX, 0x7FFFFF), /* + max normal */
SPCNST(1, SP_EMAX, 0x7FFFFF), /* - max normal */
SPCNST(0, SP_EMIN, 0x000000), /* + min normal */
diff --git a/arch/mips/math-emu/ieee754.h b/arch/mips/math-emu/ieee754.h
index df94720714c7..d3be351aed15 100644
--- a/arch/mips/math-emu/ieee754.h
+++ b/arch/mips/math-emu/ieee754.h
@@ -221,15 +221,16 @@ union ieee754dp ieee754dp_dump(char *s, union ieee754dp x);
#define IEEE754_SPCVAL_NTEN 5 /* -10.0 */
#define IEEE754_SPCVAL_PINFINITY 6 /* +inf */
#define IEEE754_SPCVAL_NINFINITY 7 /* -inf */
-#define IEEE754_SPCVAL_INDEF 8 /* quiet NaN */
-#define IEEE754_SPCVAL_PMAX 9 /* +max norm */
-#define IEEE754_SPCVAL_NMAX 10 /* -max norm */
-#define IEEE754_SPCVAL_PMIN 11 /* +min norm */
-#define IEEE754_SPCVAL_NMIN 12 /* -min norm */
-#define IEEE754_SPCVAL_PMIND 13 /* +min denorm */
-#define IEEE754_SPCVAL_NMIND 14 /* -min denorm */
-#define IEEE754_SPCVAL_P1E31 15 /* + 1.0e31 */
-#define IEEE754_SPCVAL_P1E63 16 /* + 1.0e63 */
+#define IEEE754_SPCVAL_INDEF_LEG 8 /* legacy quiet NaN */
+#define IEEE754_SPCVAL_INDEF_2008 9 /* IEEE 754-2008 quiet NaN */
+#define IEEE754_SPCVAL_PMAX 10 /* +max norm */
+#define IEEE754_SPCVAL_NMAX 11 /* -max norm */
+#define IEEE754_SPCVAL_PMIN 12 /* +min norm */
+#define IEEE754_SPCVAL_NMIN 13 /* -min norm */
+#define IEEE754_SPCVAL_PMIND 14 /* +min denorm */
+#define IEEE754_SPCVAL_NMIND 15 /* -min denorm */
+#define IEEE754_SPCVAL_P1E31 16 /* + 1.0e31 */
+#define IEEE754_SPCVAL_P1E63 17 /* + 1.0e63 */
extern const union ieee754dp __ieee754dp_spcvals[];
extern const union ieee754sp __ieee754sp_spcvals[];
@@ -243,7 +244,8 @@ extern const union ieee754sp __ieee754sp_spcvals[];
#define ieee754dp_zero(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
#define ieee754dp_one(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
#define ieee754dp_ten(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
-#define ieee754dp_indef() (ieee754dp_spcvals[IEEE754_SPCVAL_INDEF])
+#define ieee754dp_indef() (ieee754dp_spcvals[IEEE754_SPCVAL_INDEF_LEG + \
+ ieee754_csr.nan2008])
#define ieee754dp_max(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
#define ieee754dp_min(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
#define ieee754dp_mind(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
@@ -254,7 +256,8 @@ extern const union ieee754sp __ieee754sp_spcvals[];
#define ieee754sp_zero(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
#define ieee754sp_one(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
#define ieee754sp_ten(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
-#define ieee754sp_indef() (ieee754sp_spcvals[IEEE754_SPCVAL_INDEF])
+#define ieee754sp_indef() (ieee754sp_spcvals[IEEE754_SPCVAL_INDEF_LEG + \
+ ieee754_csr.nan2008])
#define ieee754sp_max(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
#define ieee754sp_min(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
#define ieee754sp_mind(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
@@ -266,12 +269,25 @@ extern const union ieee754sp __ieee754sp_spcvals[];
*/
static inline int ieee754si_indef(void)
{
- return INT_MAX;
+ return ieee754_csr.nan2008 ? 0 : INT_MAX;
}
static inline s64 ieee754di_indef(void)
{
- return S64_MAX;
+ return ieee754_csr.nan2008 ? 0 : S64_MAX;
+}
+
+/*
+ * Overflow integer value
+ */
+static inline int ieee754si_overflow(int xs)
+{
+ return ieee754_csr.nan2008 && xs ? INT_MIN : INT_MAX;
+}
+
+static inline s64 ieee754di_overflow(int xs)
+{
+ return ieee754_csr.nan2008 && xs ? S64_MIN : S64_MAX;
}
/* result types for xctx.rt */
diff --git a/arch/mips/math-emu/ieee754dp.c b/arch/mips/math-emu/ieee754dp.c
index 522d843f2ffd..ad3c73436777 100644
--- a/arch/mips/math-emu/ieee754dp.c
+++ b/arch/mips/math-emu/ieee754dp.c
@@ -37,8 +37,11 @@ static inline int ieee754dp_isnan(union ieee754dp x)
static inline int ieee754dp_issnan(union ieee754dp x)
{
+ int qbit;
+
assert(ieee754dp_isnan(x));
- return (DPMANT(x) & DP_MBIT(DP_FBITS - 1)) == DP_MBIT(DP_FBITS - 1);
+ qbit = (DPMANT(x) & DP_MBIT(DP_FBITS - 1)) == DP_MBIT(DP_FBITS - 1);
+ return ieee754_csr.nan2008 ^ qbit;
}
@@ -51,7 +54,12 @@ union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r)
assert(ieee754dp_issnan(r));
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754dp_indef();
+ if (ieee754_csr.nan2008)
+ DPMANT(r) |= DP_MBIT(DP_FBITS - 1);
+ else
+ r = ieee754dp_indef();
+
+ return r;
}
static u64 ieee754dp_get_rounding(int sn, u64 xm)
diff --git a/arch/mips/math-emu/ieee754int.h b/arch/mips/math-emu/ieee754int.h
index 6383e2c5c1ad..ed7bb277b3e0 100644
--- a/arch/mips/math-emu/ieee754int.h
+++ b/arch/mips/math-emu/ieee754int.h
@@ -63,10 +63,10 @@ static inline int ieee754_class_nan(int xc)
if (ve == SP_EMAX+1+SP_EBIAS) { \
if (vm == 0) \
vc = IEEE754_CLASS_INF; \
- else if (vm & SP_MBIT(SP_FBITS-1)) \
- vc = IEEE754_CLASS_SNAN; \
- else \
+ else if (ieee754_csr.nan2008 ^ !(vm & SP_MBIT(SP_FBITS - 1))) \
vc = IEEE754_CLASS_QNAN; \
+ else \
+ vc = IEEE754_CLASS_SNAN; \
} else if (ve == SP_EMIN-1+SP_EBIAS) { \
if (vm) { \
ve = SP_EMIN; \
@@ -97,10 +97,10 @@ static inline int ieee754_class_nan(int xc)
if (ve == DP_EMAX+1+DP_EBIAS) { \
if (vm == 0) \
vc = IEEE754_CLASS_INF; \
- else if (vm & DP_MBIT(DP_FBITS-1)) \
- vc = IEEE754_CLASS_SNAN; \
- else \
+ else if (ieee754_csr.nan2008 ^ !(vm & DP_MBIT(DP_FBITS - 1))) \
vc = IEEE754_CLASS_QNAN; \
+ else \
+ vc = IEEE754_CLASS_SNAN; \
} else if (ve == DP_EMIN-1+DP_EBIAS) { \
if (vm) { \
ve = DP_EMIN; \
diff --git a/arch/mips/math-emu/ieee754sp.c b/arch/mips/math-emu/ieee754sp.c
index ca8e35e33bf7..def00ffc50fc 100644
--- a/arch/mips/math-emu/ieee754sp.c
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -37,8 +37,11 @@ static inline int ieee754sp_isnan(union ieee754sp x)
static inline int ieee754sp_issnan(union ieee754sp x)
{
+ int qbit;
+
assert(ieee754sp_isnan(x));
- return SPMANT(x) & SP_MBIT(SP_FBITS - 1);
+ qbit = (SPMANT(x) & SP_MBIT(SP_FBITS - 1)) == SP_MBIT(SP_FBITS - 1);
+ return ieee754_csr.nan2008 ^ qbit;
}
@@ -51,7 +54,12 @@ union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r)
assert(ieee754sp_issnan(r));
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754sp_indef();
+ if (ieee754_csr.nan2008)
+ SPMANT(r) |= SP_MBIT(SP_FBITS - 1);
+ else
+ r = ieee754sp_indef();
+
+ return r;
}
static unsigned ieee754sp_get_rounding(int sn, unsigned xm)
diff --git a/arch/mips/math-emu/sp_fdp.c b/arch/mips/math-emu/sp_fdp.c
index 3797148893ad..5060e8fdcb0b 100644
--- a/arch/mips/math-emu/sp_fdp.c
+++ b/arch/mips/math-emu/sp_fdp.c
@@ -44,13 +44,16 @@ union ieee754sp ieee754sp_fdp(union ieee754dp x)
switch (xc) {
case IEEE754_CLASS_SNAN:
- return ieee754sp_nanxcpt(ieee754sp_nan_fdp(xs, xm));
-
+ x = ieee754dp_nanxcpt(x);
+ EXPLODEXDP;
+ /* Fall through. */
case IEEE754_CLASS_QNAN:
y = ieee754sp_nan_fdp(xs, xm);
- EXPLODEYSP;
- if (!ieee754_class_nan(yc))
- y = ieee754sp_indef();
+ if (!ieee754_csr.nan2008) {
+ EXPLODEYSP;
+ if (!ieee754_class_nan(yc))
+ y = ieee754sp_indef();
+ }
return y;
case IEEE754_CLASS_INF:
diff --git a/arch/mips/math-emu/sp_tint.c b/arch/mips/math-emu/sp_tint.c
index 091299a31798..f4b4cabfe2e1 100644
--- a/arch/mips/math-emu/sp_tint.c
+++ b/arch/mips/math-emu/sp_tint.c
@@ -38,10 +38,13 @@ int ieee754sp_tint(union ieee754sp x)
switch (xc) {
case IEEE754_CLASS_SNAN:
case IEEE754_CLASS_QNAN:
- case IEEE754_CLASS_INF:
ieee754_setcx(IEEE754_INVALID_OPERATION);
return ieee754si_indef();
+ case IEEE754_CLASS_INF:
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754si_overflow(xs);
+
case IEEE754_CLASS_ZERO:
return 0;
@@ -56,7 +59,7 @@ int ieee754sp_tint(union ieee754sp x)
/* Set invalid. We will only use overflow for floating
point overflow */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754si_indef();
+ return ieee754si_overflow(xs);
}
/* oh gawd */
if (xe > SP_FBITS) {
@@ -97,7 +100,7 @@ int ieee754sp_tint(union ieee754sp x)
if ((xm >> 31) != 0) {
/* This can happen after rounding */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754si_indef();
+ return ieee754si_overflow(xs);
}
if (round || sticky)
ieee754_setcx(IEEE754_INEXACT);
diff --git a/arch/mips/math-emu/sp_tlong.c b/arch/mips/math-emu/sp_tlong.c
index 9f3c742c1cea..a2450c7e452a 100644
--- a/arch/mips/math-emu/sp_tlong.c
+++ b/arch/mips/math-emu/sp_tlong.c
@@ -39,10 +39,13 @@ s64 ieee754sp_tlong(union ieee754sp x)
switch (xc) {
case IEEE754_CLASS_SNAN:
case IEEE754_CLASS_QNAN:
- case IEEE754_CLASS_INF:
ieee754_setcx(IEEE754_INVALID_OPERATION);
return ieee754di_indef();
+ case IEEE754_CLASS_INF:
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754di_overflow(xs);
+
case IEEE754_CLASS_ZERO:
return 0;
@@ -57,7 +60,7 @@ s64 ieee754sp_tlong(union ieee754sp x)
/* Set invalid. We will only use overflow for floating
point overflow */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754di_indef();
+ return ieee754di_overflow(xs);
}
/* oh gawd */
if (xe > SP_FBITS) {
@@ -94,7 +97,7 @@ s64 ieee754sp_tlong(union ieee754sp x)
if ((xm >> 63) != 0) {
/* This can happen after rounding */
ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754di_indef();
+ return ieee754di_overflow(xs);
}
if (round || sticky)
ieee754_setcx(IEEE754_INEXACT);