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User:Bjacob/ArithmeticTimingDifferences: Difference between revisions
User:Bjacob/ArithmeticTimingDifferences (view source)
Revision as of 01:02, 25 June 2013
, 25 June 2013→Handling of denormals
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=== Handling of denormals === | === Handling of denormals === | ||
x86 CPUs have two distinct flags that can optionally be enabled to enable non-IEEE-compliant handling of denormals: | x86 CPUs have two distinct flags that can optionally be enabled to enable non-IEEE-compliant handling of denormals by SSE instructions: | ||
* FTZ (Flush To Zero) causes any denormal ''result'' to be flushed to zero. | * FTZ (Flush To Zero) causes any denormal ''result'' to be flushed to zero. | ||
* DAZ (Denormals Are Zero) causes any denormal ''operand'' to be handled as if it were zero. | * DAZ (Denormals Are Zero) causes any denormal ''operand'' to be handled as if it were zero. | ||
Not all CPUs have these flags. Even CPUs with SSE2 instructions can fail to support DAZ | |||
Not all CPUs have these flags. Even CPUs with SSE2 instructions can fail to support DAZ, see below the section about that. | |||
== x86-64 architecture == | == x86-64 architecture == | ||