167338de96
These two symbols are declared in object files to indicate whether .data
needs to be copied from flash or .bss needs to be cleared. They are
supported on avr-gcc and reduce firmware size a bit, which is especially
important on very small chips.
I checked the behavior of avr-gcc and matched it as well as possible.
From my investigation, it seems to work as follows:
__do_copy_data is set when the compiler finds a data symbol:
* without a section name
* with a section name starting with ".data" or ".gnu.linkonce.d"
* with a section name starting with ".rodata" or ".gnu.linkonce.r" and
flash and RAM are in the same address space
__do_clear_bss is set when the compiler finds a data symbol:
* without a section name
* with a section name that starts with .bss
Simply checking whether the calculated section name starts with ".data",
".rodata" or ".bss" should result in the same behavior.
Fixes: https://github.com/llvm/llvm-project/issues/58857
Differential Revision: https://reviews.llvm.org/D140830
9 lines
217 B
LLVM
9 lines
217 B
LLVM
; RUN: llc < %s -march=avr | FileCheck %s
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; CHECK-NOT: .globl __do_copy_data
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; CHECK: .globl __do_clear_bss
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@noinit = internal global i8 5, section ".noinit"
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@external = external global i8
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@global = global i8 0
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