libclc: Fix FP_ILOGBNAN definition
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
GitOrigin-RevId: 3a7051d9c28e3dd6da5048d91b74fad830728e93
diff --git a/generic/include/clc/float/definitions.h b/generic/include/clc/float/definitions.h
index 43335a7..6250123 100644
--- a/generic/include/clc/float/definitions.h
+++ b/generic/include/clc/float/definitions.h
@@ -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
diff --git a/generic/lib/math/ilogb.cl b/generic/lib/math/ilogb.cl
index 7ab7899..050239c 100644
--- a/generic/lib/math/ilogb.cl
+++ b/generic/lib/math/ilogb.cl
@@ -31,7 +31,15 @@
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 @@
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;
}