Re: Auto-vectorization speeds up multiplication of large-precision numerics - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Auto-vectorization speeds up multiplication of large-precision numerics
Date
Msg-id 1644558.1599458002@sss.pgh.pa.us
Whole thread Raw
In response to Re: Auto-vectorization speeds up multiplication of large-precision numerics  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Auto-vectorization speeds up multiplication of large-precision numerics  (Amit Khandekar <amitdkhan.pg@gmail.com>)
List pgsql-hackers
I wrote:
> I made some cosmetic changes to this and committed it.

BTW, poking at this further, it seems that the patch only really
works for gcc.  clang accepts the -ftree-vectorize switch, but
looking at the generated asm shows that it does nothing useful.
Which is odd, because clang does do loop vectorization.

I tried adding -Rpass-analysis=loop-vectorize and got

numeric.c:8341:3: remark: loop not vectorized: could not determine number of loop iterations
[-Rpass-analysis=loop-vectorize]
                for (i2 = 0; i2 <= i; i2++)
                ^

which is interesting but I don't know how to proceed further.

            regards, tom lane



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