Fix for veneers generated by linker for interworking #123
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nikarh
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A compiler can do tail call optimizations, emitting R_ARM_JUMP24 relocation instead of a normal call. If this call has interworking (was from arm function to a thumb function or vice versa), binutils produces a veneer, because it needs to do a switch. By default these veneers do jumps to an absolute address. This patch forces ld to produce veneers for position independent binaries. tldr; no need for `--no-optimize-sibling-calls` anymore, sibling calls will ✨ work ✨ An example of veneer before this patch: ``` 81000010 <__func_thumb_from_arm>: 81000010: e51ff004 ldr pc, [pc, #-4] @ 0x81000014 <$d> 81000014 <$d>: 81000014: 01 00 00 81 .word 0x81000001 ``` and after: ``` 81000010 <__func_thumb_from_arm>: 81000010: e59fc004 ldr r12, [pc, vitasdk#4] @ 0x8100001c <$d> 81000014: e08fc00c add r12, pc, r12 81000018: e12fff1c bx r12 8100001c <$d>: 8100001c: e5 ff ff ff .word 0xffffffe5 ```
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Force-enables
-Wl,--pic-veneerlinker flag.A compiler can do tail-call optimizations, emitting R_ARM_JUMP24 relocation instead of a normal call.
If this call has interworking (was from an arm function to a thumb function or vice versa), binutils produces a veneer, because it needs to do a switch. By default, these veneers do jump to an absolute address. This patch forces ld to produce veneers for position-independent binaries.
tldr; no need for
--no-optimize-sibling-callsanymore, sibling calls will ✨ just work ✨An example of veneer before this patch:
and after: