[PATCH] Improve DAG combine pass on certain IR vector patterns
Fiona Glaser
fglaser at apple.com
Fri Jan 16 15:30:16 PST 2015
I checked Agner’s resources on Haswell to double-check and he says:
"However, there are fewer such delays on Haswell than on previous processors. I found no such delays in the following cases:
• when a floating point Boolean instruction, such as ORPS is used with integer data
• when a wrong type of move instruction is used, e.g. MOVPS or MOVDQA
• when a wrong type of shuffle instruction is used, e.g. SHUFPS or PFHUFD”
So it looks like there shouldn’t be any cost for a movq/movhpd pairing, at least on Haswell.
Fiona
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