368d548417
The PowerPC ISA does not have a PC-relative load instruction, which poses obvious challenges when generating position-independent code. The way the ELFv2 ABI addresses this is to specify that r2 points to a per "module" (shared library or executable) TOC pointer. Maintaining this pointer requires cooperation between codegen and the system linker: * Non-leaf functions leave space on the stack at r1+24 to save the TOC pointer. * A call to a function that *might* have to go via a PLT stub must be followed by a nop instruction that the system linker can replace with "ld r1, 24(r1)" to restore the TOC pointer (only when dynamically linking Go code). * When calling a function via a function pointer, the address of the function must be in r12, and the first couple of instructions (the "global entry point") of the called function use this to derive the address of the TOC for the module it is in. * When calling a function that is implemented in the same module, the system linker adjusts the call to skip over the instructions mentioned above (the "local entry point"), assuming that r2 is already correctly set. So this changeset adds the global entry point instructions, sets the metadata so the system linker knows where the local entry point is, inserts code to save the TOC pointer at 24(r1), adds a nop after any call not known to be local and copes with the odd non-local code transfer in the runtime (e.g. the stuff around jmpdefer). It does not actually compile PIC yet. Change-Id: I7522e22bdfd2f891745a900c60254fe9e372c854 Reviewed-on: https://go-review.googlesource.com/15967 Reviewed-by: Russ Cox <rsc@golang.org> |
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robots.txt |
The Go Programming Language
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Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set the environment variable $GOROOT to the full path of the go directory (the one containing this file). You can omit the variable if you unpack it into /usr/local/go, or if you rebuild from sources by running all.bash (see doc/install-source.html). You should also add the Go binary directory $GOROOT/bin to your shell's path.
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