)]}'
{
  "commit": "4ea7aa7cf3755533634904d934c89f93d461d642",
  "tree": "c2bbd74b1f9f4d4e5b131b0afb881039b5818722",
  "parents": [
    "24f7d89a73b7bd77127a56e8a8552c48278d251b"
  ],
  "author": {
    "name": "Cherry Zhang",
    "email": "cherryyz@google.com",
    "time": "Tue Jun 25 14:48:04 2019 -0400"
  },
  "committer": {
    "name": "Cherry Zhang",
    "email": "cherryyz@google.com",
    "time": "Wed Jun 26 16:01:47 2019 +0000"
  },
  "message": "cmd/compile, runtime: use R20, R21 in ARM64\u0027s Duff\u0027s devices\n\nCurrently we use R16 and R17 for ARM64\u0027s Duff\u0027s devices.\nAccording to ARM64 ABI, R16 and R17 can be used by the (external)\nlinker as scratch registers in trampolines. So don\u0027t use these\nregisters to pass information across functions.\n\nIt seems unlikely that calling Duff\u0027s devices would need a\ntrampoline in normal cases. But it could happen if the call\ntarget is out of the 128 MB direct jump limit.\n\nThe choice of R20 and R21 is kind of arbitrary. The register\nallocator allocates from low-numbered registers. High numbered\nregisters are chosen so it is unlikely to hold a live value and\nforces a spill.\n\nFixes #32773.\n\nChange-Id: Id22d555b5afeadd4efcf62797d1580d641c39218\nReviewed-on: https://go-review.googlesource.com/c/go/+/183842\nRun-TryBot: Cherry Zhang \u003ccherryyz@google.com\u003e\nReviewed-by: Keith Randall \u003ckhr@golang.org\u003e\n",
  "tree_diff": [
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