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Ref. #926. Fixes for LTO build. #928

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Ref. #926. Fixes for LTO build. #928

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7a9ffa9
Ref. #926. Fixes for LTO build.
Nov 8, 2022
1c93116
function signature fix for heap_newlib.cpp
ser-plu Nov 8, 2022
a096405
'used' attribute for vectorsRom
Nov 10, 2022
c5ea8ee
'used' attribute for vectorsRam and Undefined_Handler
Nov 10, 2022
0be5e03
spaces fix
Nov 10, 2022
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2 changes: 1 addition & 1 deletion src/modm/platform/core/cortex/vectors.c.in
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@ typedef void (* const FunctionPointer)(void);
extern uint32_t __main_stack_top[];

// Define the vector table
modm_section(".vector_rom")
modm_section(".vector_rom") modm_used
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probably also necessary for vectorsRam just below.

Basically everything that's implicitly linked needs to be marked as used? Seems like a lot of work…

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@salkinium salkinium Nov 10, 2022 •
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Can you perhaps extract the symbols of the resulting ELF files with/without LTO and diff them? That would perhaps give you a more definitive list of lost symbols.
It's scons symbols but we seem to not have it for CMake.
Otherwise try: arm-none-eabi-nm -S -C --size-sort -td file.elf

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I don't see much difference any more. vectorsRam indeed is required to be used, I just use the ROM-mapped vector table in my project.

One more symbol missing is modm_abandon, but I think it is just optimised out as an empty function.

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Maybe, Undefined_Handler also requires the attribute. But I am not 100% sure

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I'll have a look myself tomorrow to check if we can enable LTO by default at least for the release build.

FunctionPointer vectorsRom[] =
{
(FunctionPointer)__main_stack_top, // -16: stack pointer
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