Maxim Kuvyrkov, LCA14, Macau

LCA14-309: FSF GCC 4.10

• Performance

• Correctness

• Parity

• Energy

• AArch64

Themes

• LTO (Link-Time Optimizations)• Make sure it works for AArch32 and AArch64• Need machines with 8GB+ RAM for native

• Donate machines to lead community developers?

• RA (Register Allocation)• LRA• Rematerialization

• AArch64 performance• New scheduling pipeline descriptions• New RTX cost models

Performance

• Bugs reported by member companies• Worst kind• How can we deliver seamless compiler experience to our clients?

• Bugs reported by community• Good kind• Encourage community to fix bugs

• Bugs found within Linaro• Best kind• Automated testing bots

Correctness

• Feature parity• What are main missing features compared to x86?• Does every single feature have to be supported?

• Optimization parity• arm-linux-gnueabi -fno-<optimization> => 5% drop• i686-linux-gnu -fno-<optimization> => 8% drop

• optimization provides 8% on x86, but only 5% on ARM• Where are extra 3% of performance?

Parity

Energy

• AArch64 Performance

• AArch64 Correctness

• AArch64 Parity

AArch64

• Performance

• Correctness

• Parity

• Energy

• AArch64

Themes (reality)

• Candy for ideas

• Candy for critiques

• Candy for striking out another theme

Discussion

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