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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