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sometimes I wonder if just shipping a 64bit only no legacy instructions (i.e. cleaned up x86_64) instruction set would put a stop to the ARM is fundamentally be
by dathinab 4y ago
sometimes I wonder if just shipping a 64bit only no legacy instructions (i.e. cleaned up x86_64) instruction set would put a stop to the ARM is fundamentally better discussion (and sure there is ARM with legacy instructions etc. but Apple silicon is 64bit no legacy cruft AFIK).
- jsjohnst 4y ago> sometimes I wonder if just shipping a 64bit only no legacy instructions (i.e. cleaned up x86_64) instruction set would put a stop to the ARM is fundamentally better discussion No > but Apple silicon is 64bit no legacy cruft AFIK No. It’s an ARMv8 ISA, legacy cruft and all.
- hajile 4y agouaarch64 has very little legacy stuff left. When ARM announced A715, they got rid of uaarch32 and said it got them a 75% reduction in the size of the decoder while increasing the width of the decoder from 4 to 5-wide. They even got rid of the uop-cache because the new encoding was so much smaller and efficient that it didn't make sense to keep it around.
- dathinab 4y agothrough its A64 only (no T32 neither A32) which cuts out a lot of legacy instructions/instruction variants. Doing the same for x86_64 would be a bit like no 16bit and 32bit specific machine instructions/instruction variants, no support for legacy bios things etc.