- 09 Jul, 2018 1 commit
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Sigurd Schneider authored
This CL uses pc-relative jumps and calls (B/BL) for calls from embedded builtins to embedded builtins. To make this work, the code range size is limited to 32MB on arm during mksnapshot, which ensures that all builtin to builtin offsets for jumps/calls fit into the B/BL immediate. At code generation time, we put a placeholder into the instruction offset which we resolve to the right code object when the code is copied to the heap. We use a new relocation mode RELATIVE_CODE_TARGET for these relative jumps. The relocation mode RELATIVE_CODE_TARGET should never appear after generating the snapshot. We modify the target_address/set_target_address methods of RelocInfo such that they return the absolute target addresses for pc-relative B/BL instructions. This ensures that the GC can treat RELATIVE_CODE_TARGET in the same way as code targets. This, however, only matters during snapshot creation time, and production code never contains RELATIVE_CODE_TARGET relocations. Bug: v8:6666 Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng Change-Id: If7eab83ad588859ca87c654a5ddc3e37caea884c Reviewed-on: https://chromium-review.googlesource.com/1117181Reviewed-by: Michael Starzinger <mstarzinger@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Reviewed-by: Jakob Gruber <jgruber@chromium.org> Commit-Queue: Sigurd Schneider <sigurds@chromium.org> Cr-Commit-Position: refs/heads/master@{#54320}
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- 26 Jun, 2018 1 commit
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Sigurd Schneider authored
We had a kRootRegisterBias on x64 before. This CL ports the feature to all other platforms as well. The root register bias is helpful to adjust the value of the root register, which allows to better utilize signed immediate offset constants in load instructions. We currently use a separate add instruction to add kRootRegisterBias in the code that initializes the root register. This could be improved by adding a custom relocation mode ensuring that instead of the root address, the root address plus the bias is inserted (and in this way the add instruction can be omitted). Bug: v8:6666 Change-Id: I55cf02ab85d11e3c6d0d83a8f7905dbf924890f1 Reviewed-on: https://chromium-review.googlesource.com/1113539 Commit-Queue: Sigurd Schneider <sigurds@chromium.org> Reviewed-by: Jakob Gruber <jgruber@chromium.org> Cr-Commit-Position: refs/heads/master@{#54023}
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