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libclc: Fix FP_ILOGBNAN definition

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Fix FP_ILOGBNAN definition to match the opencl-c-base.h one and
guarantee that FP_ILOGBNAN and FP_ILOGB0 are different. Doing that
implies fixing ilogb() implementation to return the right value.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

Reviewed By: jvesely

Differential Revision: https://reviews.llvm.org/D83473
This commit is contained in:
Boris Brezillon 2020-08-17 13:44:01 -07:00 committed by Tom Stellard
parent 45cc86b09b
commit 3a7051d9c2
2 changed files with 19 additions and 3 deletions
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2
libclc/generic/include/clc/float/definitions.h
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@ -15,7 +15,7 @@
#define FLT_EPSILON 0x1.0p-23f
#define FP_ILOGB0 (-2147483647 - 1)
#define FP_ILOGBNAN (-2147483647 - 1)
#define FP_ILOGBNAN 2147483647
#define M_E_F 0x1.5bf0a8p+1f
#define M_LOG2E_F 0x1.715476p+0f

20
libclc/generic/lib/math/ilogb.cl
View File

@ -31,7 +31,15 @@ _CLC_OVERLOAD _CLC_DEF int ilogb(float x) {
int rs = -118 - (int) clz(ux & MANTBITS_SP32);
int r = (int) (ax >> EXPSHIFTBITS_SP32) - EXPBIAS_SP32;
r = ax < 0x00800000U ? rs : r;
r = ax > EXPBITS_SP32 | ax == 0 ? 0x80000000 : r;
r = ax == 0 ? FP_ILOGB0 : r;
// We could merge those 2 tests and have:
//
// r = ax >= EXPBITS_SP32 ? 0x7fffffff : r
//
// since FP_ILOGBNAN is set to INT_MAX, but it's clearer this way and
// FP_ILOGBNAN can change without requiring changes to ilogb() code.
r = ax > EXPBITS_SP32 ? FP_ILOGBNAN : r;
r = ax == EXPBITS_SP32 ? 0x7fffffff : r;
return r;
}
@ -47,7 +55,15 @@ _CLC_OVERLOAD _CLC_DEF int ilogb(double x) {
int r = (int) (ax >> EXPSHIFTBITS_DP64) - EXPBIAS_DP64;
int rs = -1011 - (int) clz(ax & MANTBITS_DP64);
r = ax < 0x0010000000000000UL ? rs : r;
r = ax > 0x7ff0000000000000UL | ax == 0UL ? 0x80000000 : r;
r = ax == 0UL ? FP_ILOGB0 : r;
// We could merge those 2 tests and have:
//
// r = ax >= 0x7ff0000000000000UL ? 0x7fffffff : r
//
// since FP_ILOGBNAN is set to INT_MAX, but it's clearer this way and
// FP_ILOGBNAN can change without requiring changes to ilogb() code.
r = ax > 0x7ff0000000000000UL ? FP_ILOGBNAN : r;
r = ax == 0x7ff0000000000000UL ? 0x7fffffff : r;
return r;
}