GCC 9 support #2103

avtolstoy · 2020-05-15T10:55:10Z

Description

Resolves various issues/warnings encountered when building with GCC9, switches over the CI to using GCC9.

Updates Workbench manifest with GCC 9 support as well.

Steps to Test

N/A

Example App

N/A

References

[CH42647]

Completeness

User is totes amazing for contributing!
Contributor has signed CLA (Info here)
Problem and Solution clearly stated
Run unit/integration/application tests on device
Added documentation
Added to CHANGELOG.md after merging (add links to docs and issues)

avtolstoy · 2020-05-15T10:58:37Z

bootloader/src/main.c

+            // Jump to system firmware
+            uint32_t addr = *(volatile uint32_t*)(ApplicationAddress + 4);
+            uint32_t stack = *(volatile uint32_t*)ApplicationAddress;
+            jump_to_system(addr, stack);


For reference: this is required because GCC9 now throws a deprecated error when calling CMSIS __set_MSP(), which clobbers sp, which is in fact not what is supposed to happen.

A quote from recent gcc docs:

Another restriction is that the clobber list should not contain the stack pointer register. This is because the compiler requires the value of the stack pointer to be the same after an asm statement as it was on entry to the statement. However, previous versions of GCC did not enforce this rule and allowed the stack pointer to appear in the list, with unclear semantics. This behavior is deprecated and listing the stack pointer may become an error in future versions of GCC.

avtolstoy · 2020-05-15T10:59:43Z

hal/src/electron/core_hal.c

-extern char link_interrupt_vectors_location;
-extern char link_ram_interrupt_vectors_location;
-extern char link_ram_interrupt_vectors_location_end;
+extern uintptr_t link_interrupt_vectors_location[];


For reference: this is now required because of array bounds checks warnings in GCC9.

avtolstoy · 2020-05-15T11:00:54Z

wiring/src/spark_wiring_string.cpp

@@ -830,9 +830,3 @@ String String::format(const char* fmt, ...)
    }
    return result;
 }
-
-std::ostream& operator << ( std::ostream& os, const String& value ) {


For reference: this was a source of a major binary size bloat due to the usage of iostreams, which was bringing std strings, locales, exceptions and system_error stuff into the binary no matter what.

Is this a breaking change that we ought to announce? What would be typical usage? Something like Serial << String("foo") ? Once that's clear I can check with Studios if they use this pattern in any application.

This is not a breaking change. DeviceOS does not support iostreams in any form. I have no explanation why that code was there if only for unit tests. For the example you listed to work Serial would have to be a subclass of std::ostream, which it isn't and none of the other wiring classes are.

avtolstoy · 2020-05-15T11:05:35Z

wiring/inc/spark_wiring_print.h

@@ -127,12 +127,20 @@ size_t Print::print(T n, int base)
        size_t t = 0;
        using PrintNumberType = typename PrintNumberTypeSelector<T>::type;
        PrintNumberType val;
+// FIXME: avoids 'comparison of constant '0' with boolean expression is always false'
+#if __GNUC__ >= 9


Adding a separate bool specialization brings its own set of problems, so for now we are disabling this warning here specifically as a workaround.

…son file

…loat

…rning

monkbroc

👍 I verified the compilation on Workbench on Linux for all platforms.

monkbroc · 2020-05-15T16:51:15Z

wiring/src/spark_wiring_string.cpp

@@ -830,9 +830,3 @@ String String::format(const char* fmt, ...)
    }
    return result;
 }
-
-std::ostream& operator << ( std::ostream& os, const String& value ) {


Is this a breaking change that we ought to announce? What would be typical usage? Something like Serial << String("foo") ? Once that's clear I can check with Studios if they use this pattern in any application.

elcojacobs · 2020-08-27T21:11:03Z

I'm very happy that the compiler has finally been upgraded!
Just compiled against 2.0.0-rc.1 and apart from the simple api deprecations changes, there seem to be no issues for my huge application.

Now that we run on gcc 9, can the makefiles for a local build be upgraded to use C++17 too? The still use std=gnu++14?

Changing the standard in lang-std.mk will give many warnings in STM32 includes about the deprecated register specifier:
ISO C++17 does not allow 'register' storage class specifier.

avtolstoy · 2020-08-28T08:27:44Z

We aren't changing the C++ standard version for 2.x. We'll migrate most likely to C++20 in 3.x.

avtolstoy requested a review from XuGuohui May 15, 2020 10:55

avtolstoy added needs review enhancement labels May 15, 2020

avtolstoy requested a review from busticated May 15, 2020 10:55

avtolstoy added this to the 2.0.0 milestone May 15, 2020

avtolstoy commented May 15, 2020

View reviewed changes

avtolstoy requested a review from sergeuz May 15, 2020 10:58

avtolstoy commented May 15, 2020

View reviewed changes

avtolstoy force-pushed the feature/mesh-deprecation branch from 7af8a5c to 00820ab Compare May 15, 2020 13:13

XuGuohui and others added 14 commits May 15, 2020 20:41

Fixes compilation errors when using GCC 9.

5006bf0

switch over to gcc9

fa0e378

workbench's manifest.json file uses gcc-arm v9.2.1

331fca5

remove xenon from deviceOS@source toolchain in workbench's manifest.j…

0dcc213

…son file

[bootloader] use dedicated function to jump to deviceos

dcc6147

[test] wiring/api: make gcc9 happy

5101e44

[wiring] print: make gcc9 happy with bool argument in print()

44afa76

[wiring] string: remove ostream& operator<<, it's a major source of b…

07d1a90

…loat

[wiring] add missing headers

d115975

[test] wiring/no_fixture: avoid warnings

196020a

[wiring] print: cast to PrintNumberType to avoid a bool comparison wa…

02bdf90

…rning

[newhal] minor fix to build with gcc9

3c0a094

[wiring] print: give up - pragma diagnostic -Wbool-compare

1b9d811

[scripts] updates buildpack builder to 0.0.10

2c9237e

avtolstoy force-pushed the enhancement/bump_gcc_version/ch42647 branch from d226118 to 2c9237e Compare May 15, 2020 13:42

avtolstoy changed the base branch from feature/mesh-deprecation to develop May 15, 2020 13:43

avtolstoy requested review from DebbieGillespie and eberseth and removed request for DebbieGillespie May 15, 2020 14:39

avtolstoy requested a review from monkbroc May 15, 2020 15:14

busticated approved these changes May 15, 2020

View reviewed changes

monkbroc approved these changes May 15, 2020

View reviewed changes

avtolstoy removed request for XuGuohui, sergeuz and eberseth May 15, 2020 17:02

avtolstoy added ready to merge PR has been reviewed and tested and removed needs review labels May 15, 2020

avtolstoy merged commit 09439c9 into develop May 15, 2020

avtolstoy deleted the enhancement/bump_gcc_version/ch42647 branch May 15, 2020 18:11

avtolstoy mentioned this pull request Nov 19, 2020

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GCC 9 support #2103

GCC 9 support #2103

avtolstoy commented May 15, 2020 •

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elcojacobs commented Aug 27, 2020 •

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avtolstoy commented Aug 28, 2020

GCC 9 support #2103

GCC 9 support #2103

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avtolstoy commented May 15, 2020 • edited Loading

Description

Steps to Test

Example App

References

Completeness

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elcojacobs commented Aug 27, 2020 • edited Loading

avtolstoy commented Aug 28, 2020

avtolstoy commented May 15, 2020 •

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elcojacobs commented Aug 27, 2020 •

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