================
@@ -66,13 +65,11 @@ bool __attribute__((noinline))
__clc_runtime_has_hw_fma32(void);
#define LOG_MAGIC_NUM_SP32 (1 + NUMEXPBITS_SP32 - EXPBIAS_SP32)
_CLC_OVERLOAD _CLC_INLINE float __clc_flush_denormal_if_not_supported(float x)
{
- int ix = __clc_as_int(x);
- if (!__clc_fp32_subnormals_supported() && ((ix & EXPBITS_SP32) == 0) &&
- ((ix & MANTBITS_SP32) != 0)) {
- ix &= SIGNBIT_SP32;
- x = __clc_as_float(ix);
- }
- return x;
+ // Avoid calling __clc_fp32_subnormals_supported here: it uses
+ // llvm.canonicalize, which quiets sNaN.
+ return __builtin_fabsf(x) < 0x1p-149f
+ ? __builtin_elementwise_copysign(0.0f, x)
+ : x;
----------------
arsenm wrote:
The name is now right, but the usage is not. You do not want to unconditionally
force a denormal flush, pretty much anywhere.
I also believe most of the explicit flushes / canonicalizes in the math
function implementations can be deleted with some shuffling around. I removed
most of these in the rocm-device-libs implementations a few years ago. A few
more remain but I believe they can also be avoided
https://github.com/llvm/llvm-project/pull/157633
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