pkg/dwarf: do not insist stmt is same line as entry #4186
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This invariant does not hold for optimized binaries. For the example program included in this patch, the disassembly of the function for an optimized build looks like the following: ``` TEXT main.ManyArgsWithNamedReturns(SB) /home/deparker/Code/delve/_fixtures/multinamedreturns.go multinamedreturns.go:24 0x4a9f40 4c894c2470 mov qword ptr [rsp+0x70], r9 multinamedreturns.go:24 0x4a9f45 4c899c2480000000 mov qword ptr [rsp+0x80], r11 => multinamedreturns.go:7 0x4a9f4d 488d1403 lea rdx, ptr [rbx+rax*1] multinamedreturns.go:7 0x4a9f51 4801ca add rdx, rcx multinamedreturns.go:7 0x4a9f54 4801fa add rdx, rdi multinamedreturns.go:7 0x4a9f57 4801f2 add rdx, rsi multinamedreturns.go:7 0x4a9f5a 4c01c2 add rdx, r8 multinamedreturns.go:7 0x4a9f5d 4c01ca add rdx, r9 multinamedreturns.go:7 0x4a9f60 4c01d2 add rdx, r10 ... ``` As you can see the entry is marked as line 24, whereas the first line we really want to stop at is line 7 in this build. Enforcing that we want to find a statement with the same line as the entry, this makes Delve stop at the end at the `ret` instruction: ``` multinamedreturns.go:22 0x4aa01b 488d1c11 lea rbx, ptr [rcx+rdx*1] multinamedreturns.go:22 0x4aa01f 48d1fb sar rbx, 0x1 multinamedreturns.go:24 0x4aa022 c3 ret ```
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This invariant does not hold for optimized binaries. For the example program included in this patch, the disassembly of the function for an optimized build looks like the following:
As you can see the entry is marked as line 24, whereas the first line we
really want to stop at is line 7 in this build. Enforcing that we want
to find a statement with the same line as the entry, this makes Delve
stop at the end at the
retinstruction: