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30f8074e35
This commit adds a new option to the x86 assembler. If the GOAMD64 environment variable is set to alignedjumps (the default) and we're doing a 64 bit build, the assembler will make sure that neither stand alone nor macro-fused jumps will end on or cross 32 byte boundaries. To achieve this, functions are aligned on 32 byte boundaries, rather than 16 bytes, and jump instructions are padded to ensure that they do not cross or end on 32 byte boundaries. Jumps are padded by adding a NOP instruction of the appropriate length before the jump. The commit is likely to result in larger binary sizes when GOAMD64=alignedjumps. On the binaries tested so far, an increase of between 1.4% and 1.5% has been observed. Updates #35881 Co-authored-by: David Chase <drchase@google.com> Change-Id: Ief0722300bc3f987098e4fd92b22b14ad6281d91 Reviewed-on: https://go-review.googlesource.com/c/go/+/219357 Reviewed-by: Cherry Zhang <cherryyz@google.com> Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>