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option -mprfchw
- From: NightStrike <nightstrike at gmail dot com>
- To: gcc-help <gcc-help at gcc dot gnu dot org>
- Date: Mon, 18 Apr 2016 00:26:26 -0400
- Subject: option -mprfchw
- Authentication-results: sourceware.org; auth=none
Not sure if this applies:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54210
If I compile on a k8 Opteron 248 with -march=native, I do not see
-mprfchw listed in the options in -fverbose-asm. In the assembly, I
see this:
prefetcht0 (%rax) # ivtmp.1160
prefetcht0 304(%rcx) #
prefetcht0 (%rax) # ivtmp.1160
If I compile on a bdver2 Opteron 6386 SE with -march=k8 (thus trying
to target the older system), I do see it listed in the options in
-fverbose-asm. In the assembly, I see this:
prefetcht0 (%rax) # ivtmp.1160
prefetcht0 304(%rcx) #
prefetchw (%rax) # ivtmp.1160
(The third line is the only difference)
In both cases, I'm using gcc 4.9.3. Which is correct for a k8 Opteron 248?