RFR(M): 8027754: Enable loop optimizations for loops with MathExact inside (original) (raw)

Rickard Bäckman rickard.backman at oracle.com
Fri Jan 24 03:48:01 PST 2014

Florian,

thanks for the suggestion and catching that mistake. New webrev is on its ways.

/R

On 01/24, Florian Weimer wrote:

On 01/23/2014 12:27 PM, Rickard Bäckman wrote:

>In the end we generate assembly like: > >mov rdx, rdi >add rdx, rsi >... >mov rax, rdi >add rax, rsi >jo > >With one add instruction for the data and one for flags. Future >improvements could be to try to match the Overflow and the math >operation and remove one of them. You could use cmp instead of sub on x86 for the overflow case, which should be beneficial because the cmp instruction preserves both inputs and only updates the flags. Unfortunately, there is no similar companion instruction in the other cases, so I'm not sure if that's worth the effort. The mulofIrRegimm pattern definitions in x8632.ad and x8664.ad do not include the immediate operand in the format string. -- Florian Weimer / Red Hat Product Security Team -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 836 bytes Desc: Digital signature Url : http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/attachments/20140124/4574107f/attachment.bin

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