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authorGabe Black <gblack@eecs.umich.edu>2010-06-02 12:58:15 -0500
committerGabe Black <gblack@eecs.umich.edu>2010-06-02 12:58:15 -0500
commit347ab6c7045bc800c2c00239b37981571e3893dc (patch)
tree8cdd9391ca543c9107474c562b3df3d08983e957 /src/arch/arm/insts/vfp.hh
parentfd82a47b964016332611dbe768762377531a3619 (diff)
downloadgem5-347ab6c7045bc800c2c00239b37981571e3893dc.tar.xz
ARM: Compensate for ARM's underflow coming from -before- rounding, but x86's after.
Diffstat (limited to 'src/arch/arm/insts/vfp.hh')
-rw-r--r--src/arch/arm/insts/vfp.hh118
1 files changed, 110 insertions, 8 deletions
diff --git a/src/arch/arm/insts/vfp.hh b/src/arch/arm/insts/vfp.hh
index e32aac721..11ae8ed96 100644
--- a/src/arch/arm/insts/vfp.hh
+++ b/src/arch/arm/insts/vfp.hh
@@ -175,6 +175,30 @@ bitsToFp(uint64_t bits, double junk)
template <class fpType>
static inline fpType
+fixDest(FPSCR fpscr, fpType val, fpType op1)
+{
+ int fpClass = std::fpclassify(val);
+ fpType junk = 0.0;
+ if (fpClass == FP_NAN) {
+ const bool single = (sizeof(val) == sizeof(float));
+ const uint64_t qnan = single ? 0x7fc00000 : ULL(0x7ff8000000000000);
+ const bool nan = std::isnan(op1);
+ if (!nan || (fpscr.dn == 1)) {
+ val = bitsToFp(qnan, junk);
+ } else if (nan) {
+ val = bitsToFp(fpToBits(op1) | qnan, junk);
+ }
+ } else if (fpClass == FP_SUBNORMAL && fpscr.fz == 1) {
+ // Turn val into a zero with the correct sign;
+ uint64_t bitMask = ULL(0x1) << (sizeof(fpType) * 8 - 1);
+ val = bitsToFp(fpToBits(val) & bitMask, junk);
+ feraiseexcept(FeUnderflow);
+ }
+ return val;
+}
+
+template <class fpType>
+static inline fpType
fixDest(FPSCR fpscr, fpType val, fpType op1, fpType op2)
{
int fpClass = std::fpclassify(val);
@@ -206,6 +230,84 @@ fixDest(FPSCR fpscr, fpType val, fpType op1, fpType op2)
return val;
}
+template <class fpType>
+static inline fpType
+fixMultDest(FPSCR fpscr, fpType val, fpType op1, fpType op2)
+{
+ fpType mid = fixDest(fpscr, val, op1, op2);
+ const bool single = (sizeof(fpType) == sizeof(float));
+ const fpType junk = 0.0;
+ if ((single && (val == bitsToFp(0x00800000, junk) ||
+ val == bitsToFp(0x80800000, junk))) ||
+ (!single && (val == bitsToFp(ULL(0x0010000000000000), junk) ||
+ val == bitsToFp(ULL(0x8010000000000000), junk)))
+ ) {
+ __asm__ __volatile__("" : "=m" (op1) : "m" (op1));
+ fesetround(FeRoundZero);
+ fpType temp = 0.0;
+ __asm__ __volatile__("" : "=m" (temp) : "m" (temp));
+ temp = op1 * op2;
+ if (!std::isnormal(temp)) {
+ feraiseexcept(FeUnderflow);
+ }
+ __asm__ __volatile__("" :: "m" (temp));
+ }
+ return mid;
+}
+
+template <class fpType>
+static inline fpType
+fixDivDest(FPSCR fpscr, fpType val, fpType op1, fpType op2)
+{
+ fpType mid = fixDest(fpscr, val, op1, op2);
+ const bool single = (sizeof(fpType) == sizeof(float));
+ const fpType junk = 0.0;
+ if ((single && (val == bitsToFp(0x00800000, junk) ||
+ val == bitsToFp(0x80800000, junk))) ||
+ (!single && (val == bitsToFp(ULL(0x0010000000000000), junk) ||
+ val == bitsToFp(ULL(0x8010000000000000), junk)))
+ ) {
+ __asm__ __volatile__("" : "=m" (op1) : "m" (op1));
+ fesetround(FeRoundZero);
+ fpType temp = 0.0;
+ __asm__ __volatile__("" : "=m" (temp) : "m" (temp));
+ temp = op1 / op2;
+ if (!std::isnormal(temp)) {
+ feraiseexcept(FeUnderflow);
+ }
+ __asm__ __volatile__("" :: "m" (temp));
+ }
+ return mid;
+}
+
+static inline float
+fixFpDFpSDest(FPSCR fpscr, double val)
+{
+ const float junk = 0.0;
+ float op1 = 0.0;
+ if (std::isnan(val)) {
+ uint64_t valBits = fpToBits(val);
+ uint32_t op1Bits = bits(valBits, 50, 29) |
+ (mask(9) << 22) |
+ (bits(valBits, 63) << 31);
+ op1 = bitsToFp(op1Bits, junk);
+ }
+ float mid = fixDest(fpscr, (float)val, op1);
+ if (mid == bitsToFp(0x00800000, junk) ||
+ mid == bitsToFp(0x80800000, junk)) {
+ __asm__ __volatile__("" : "=m" (val) : "m" (val));
+ fesetround(FeRoundZero);
+ float temp = 0.0;
+ __asm__ __volatile__("" : "=m" (temp) : "m" (temp));
+ temp = val;
+ if (!std::isnormal(temp)) {
+ feraiseexcept(FeUnderflow);
+ }
+ __asm__ __volatile__("" :: "m" (temp));
+ }
+ return mid;
+}
+
static inline uint64_t
vfpFpSToFixed(float val, bool isSigned, bool half, uint8_t imm)
{
@@ -282,7 +384,7 @@ vfpFpSToFixed(float val, bool isSigned, bool half, uint8_t imm)
}
static inline float
-vfpUFixedToFpS(uint32_t val, bool half, uint8_t imm)
+vfpUFixedToFpS(FPSCR fpscr, uint32_t val, bool half, uint8_t imm)
{
fesetround(FeRoundNearest);
if (half)
@@ -291,11 +393,11 @@ vfpUFixedToFpS(uint32_t val, bool half, uint8_t imm)
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
feclearexcept(FeAllExceptions);
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
- return val / scale;
+ return fixDivDest(fpscr, val / scale, (float)val, scale);
}
static inline float
-vfpSFixedToFpS(int32_t val, bool half, uint8_t imm)
+vfpSFixedToFpS(FPSCR fpscr, int32_t val, bool half, uint8_t imm)
{
fesetround(FeRoundNearest);
if (half)
@@ -304,7 +406,7 @@ vfpSFixedToFpS(int32_t val, bool half, uint8_t imm)
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
feclearexcept(FeAllExceptions);
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
- return val / scale;
+ return fixDivDest(fpscr, val / scale, (float)val, scale);
}
static inline uint64_t
@@ -383,7 +485,7 @@ vfpFpDToFixed(double val, bool isSigned, bool half, uint8_t imm)
}
static inline double
-vfpUFixedToFpD(uint32_t val, bool half, uint8_t imm)
+vfpUFixedToFpD(FPSCR fpscr, uint32_t val, bool half, uint8_t imm)
{
fesetround(FeRoundNearest);
if (half)
@@ -392,11 +494,11 @@ vfpUFixedToFpD(uint32_t val, bool half, uint8_t imm)
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
feclearexcept(FeAllExceptions);
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
- return val / scale;
+ return fixDivDest(fpscr, val / scale, (double)val, scale);
}
static inline double
-vfpSFixedToFpD(int32_t val, bool half, uint8_t imm)
+vfpSFixedToFpD(FPSCR fpscr, int32_t val, bool half, uint8_t imm)
{
fesetround(FeRoundNearest);
if (half)
@@ -405,7 +507,7 @@ vfpSFixedToFpD(int32_t val, bool half, uint8_t imm)
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
feclearexcept(FeAllExceptions);
__asm__ __volatile__("" : "=m" (scale) : "m" (scale));
- return val / scale;
+ return fixDivDest(fpscr, val / scale, (double)val, scale);
}
typedef int VfpSavedState;