[OE-core] [PATCH] arch-arm: Do not add -march options for arm architecture

[Andre McCurdy]

On Wed, Jan 23, 2019 at 12:05 PM Khem Raj <raj.khem at gmail.com> wrote:
>
> tune files which inherit the arch definitions already define appropriate
> -mcpu option, which is equivalent of right -march and -mtune combination

And what about machines which inherit an arch definition instead of a
cpu definition? Is that no longer supported?

> and is preferred since gcc is getting stricter and stricter with option
> check semantics and can now find incompatible -march and -mcpu options
> better with every release. It does internal feature consistency check
> and if it finds out discrepency between what -mcpu would expand to as
> compared to -march it will flag the options to be incompatible, for
> naked eye it sounds wrong but gcc would translate -mcpu to a given
> -march internally and it might not match to what we set in these arch
> files.
>
> The effects are quite subtle, where this can result in configure test
> failing to compile due to these incompatible options and a feature
> option getting disabled for a recipe for no reason.
>
> e.g. with gcc9 which can now detect that -mcpu=cortex-a5 and
> -march=armv7-a are incompatible, many features in libstdc++ ends up
> disabled due to configure check failures e.g. size_t size, ptrdiff_t
> sizes, which inturn results in compiling libstdc++ with unwanted
> disabled features.

It would be interesting to see more specific details of this.

> Signed-off-by: Khem Raj <raj.khem at gmail.com>
> ---
>  meta/conf/machine/include/arm/arch-armv4.inc   | 1 -
>  meta/conf/machine/include/arm/arch-armv5.inc   | 1 -
>  meta/conf/machine/include/arm/arch-armv6.inc   | 1 -
>  meta/conf/machine/include/arm/arch-armv7a.inc  | 1 -
>  meta/conf/machine/include/arm/arch-armv7ve.inc | 1 -
>  meta/conf/machine/include/tune-iwmmxt.inc      | 2 +-
>  6 files changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/meta/conf/machine/include/arm/arch-armv4.inc b/meta/conf/machine/include/arm/arch-armv4.inc
> index 47a7ad2830..52d8ab1e8f 100644
> --- a/meta/conf/machine/include/arm/arch-armv4.inc
> +++ b/meta/conf/machine/include/arm/arch-armv4.inc
> @@ -2,7 +2,6 @@ DEFAULTTUNE ?= "armv4"
>
>  TUNEVALID[arm] = "Enable ARM instruction set"
>  TUNEVALID[armv4] = "Enable instructions for ARMv4"
> -TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'armv4', ' -march=armv4t', '', d)}"
>  # enable --fix-v4bx when we have armv4 in TUNE_FEATURES, but then disable it when we have also armv5 or thumb
>  # maybe we should extend bb.utils.contains to support check for any checkvalues in value, now it does
>  # checkvalues.issubset(val) which cannot be used for negative test of foo neither bar in value
> diff --git a/meta/conf/machine/include/arm/arch-armv5.inc b/meta/conf/machine/include/arm/arch-armv5.inc
> index f9068af9de..1fe1b6b8e4 100644
> --- a/meta/conf/machine/include/arm/arch-armv5.inc
> +++ b/meta/conf/machine/include/arm/arch-armv5.inc
> @@ -2,7 +2,6 @@ DEFAULTTUNE ?= "armv5"
>
>  TUNEVALID[armv5] = "Enable instructions for ARMv5"
>  TUNECONFLICTS[armv5] = "armv4"
> -TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'armv5', ' -march=armv5t${ARMPKGSFX_DSP}', '', d)}"
>  MACHINEOVERRIDES =. "${@bb.utils.contains('TUNE_FEATURES', 'armv5', 'armv5:', '' ,d)}"
>
>  require conf/machine/include/arm/arch-armv4.inc
> diff --git a/meta/conf/machine/include/arm/arch-armv6.inc b/meta/conf/machine/include/arm/arch-armv6.inc
> index 6c838e999c..adb9be8050 100644
> --- a/meta/conf/machine/include/arm/arch-armv6.inc
> +++ b/meta/conf/machine/include/arm/arch-armv6.inc
> @@ -2,7 +2,6 @@ DEFAULTTUNE ?= "armv6hf"
>
>  TUNEVALID[armv6] = "Enable instructions for ARMv6"
>  TUNECONFLICTS[armv6] = "armv4 armv5"
> -TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'armv6', ' -march=armv6', '', d)}"
>  MACHINEOVERRIDES =. "${@bb.utils.contains('TUNE_FEATURES', 'armv6', 'armv6:', '' ,d)}"
>
>  require conf/machine/include/arm/arch-armv5-dsp.inc
> diff --git a/meta/conf/machine/include/arm/arch-armv7a.inc b/meta/conf/machine/include/arm/arch-armv7a.inc
> index a2663d8008..09d2c03a5d 100644
> --- a/meta/conf/machine/include/arm/arch-armv7a.inc
> +++ b/meta/conf/machine/include/arm/arch-armv7a.inc
> @@ -3,7 +3,6 @@ ARM_INSTRUCTION_SET ?= "thumb"
>
>  TUNEVALID[armv7a] = "Enable instructions for ARMv7-a"
>  TUNECONFLICTS[armv7a] = "armv4 armv5 armv6 armv7"
> -TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'armv7a', ' -march=armv7-a', '', d)}"
>  MACHINEOVERRIDES =. "${@bb.utils.contains('TUNE_FEATURES', 'armv7a', 'armv7a:', '' ,d)}"
>
>  require conf/machine/include/arm/arch-armv6.inc
> diff --git a/meta/conf/machine/include/arm/arch-armv7ve.inc b/meta/conf/machine/include/arm/arch-armv7ve.inc
> index 4d9260fecb..31e334f645 100644
> --- a/meta/conf/machine/include/arm/arch-armv7ve.inc
> +++ b/meta/conf/machine/include/arm/arch-armv7ve.inc
> @@ -2,7 +2,6 @@ DEFAULTTUNE ?= "armv7vethf"
>
>  TUNEVALID[armv7ve] = "Enable instructions for ARMv7ve"
>  TUNECONFLICTS[armv7ve] = "armv4 armv5 armv6 armv7 armv7a"
> -TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'armv7ve', ' -march=armv7ve', '', d)}"
>  MACHINEOVERRIDES =. "${@bb.utils.contains('TUNE_FEATURES', 'armv7ve', 'armv7ve:', '' ,d)}"
>
>  require conf/machine/include/arm/arch-armv7a.inc
> diff --git a/meta/conf/machine/include/tune-iwmmxt.inc b/meta/conf/machine/include/tune-iwmmxt.inc
> index f27423cb2e..6e577697cc 100644
> --- a/meta/conf/machine/include/tune-iwmmxt.inc
> +++ b/meta/conf/machine/include/tune-iwmmxt.inc
> @@ -6,7 +6,7 @@ DEFAULTTUNE ?= "iwmmxt"
>  require conf/machine/include/arm/arch-armv5-dsp.inc
>
>  TUNEVALID[iwmmxt] = "Enable Intel PXA27x specific processor optimizations"
> -TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'iwmmxt', ' -march=iwmmxt -mcpu=iwmmxt', '', d)}"
> +TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'iwmmxt', ' -mcpu=iwmmxt', '', d)}"
>
>  AVAILTUNES += "iwmmxt"
>  ARMPKGARCH_tune-iwmmxt = "iwmmxt"
> --
> 2.20.1
>
> --
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