Use target_cpu instead of cpu_arch in BUILD.gn

Use target_cpu instead of cpu_arch in BUILD.gn

Also add missing defines for arm simulator build

BUG=v8:3841
R=machenbach@chromium.org
LOG=n

Committed: https://crrev.com/6b8428748ebcb13c262e40f53d5b77cdc9f7f516
Cr-Commit-Position: refs/heads/master@{#27164}

[jochen (gone - plz use gerrit), 2015-01-27 08:45:27]

apparently, the chromium gn config isn't up for this yet...

[Michael Achenbach, 2015-01-27 12:43:28]

Generally lg, no idea what's missing.

[jochen (gone - plz use gerrit), 2015-02-23 20:23:55]

jochen@chromium.org changed reviewers:
+ dpranke@chromium.org

[jochen (gone - plz use gerrit), 2015-02-23 20:23:56]

ptal

[Dirk Pranke, 2015-02-23 20:25:50]

Can this wait until after https://codereview.chromium.org/946023002/ lands, or
do you want me to abandon my change?

https://codereview.chromium.org/874393007/diff/1/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/874393007/diff/1/BUILD.gn#newcode103
BUILD.gn:103: if (cpu_arch == "arm") {
This will need to be current_cpu.

[jochen (gone - plz use gerrit), 2015-02-24 10:27:16]

closing this CL as discussed

[jochen (gone - plz use gerrit), 2015-03-12 12:27:46]

ptal

[Yang, 2015-03-12 15:18:35]

On 2015/03/12 12:27:46, jochen (slow) wrote:
> ptal

lgtm.

[jochen (gone - plz use gerrit), 2015-03-12 15:26:19]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2015-03-12 15:26:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/874393007/60001

[commit-bot: I haz the power, 2015-03-12 15:39:45]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-03-12 15:39:54]

Patchset 4 (id:??) landed as
https://crrev.com/6b8428748ebcb13c262e40f53d5b77cdc9f7f516
Cr-Commit-Position: refs/heads/master@{#27164}

[Dirk Pranke, 2015-03-12 17:53:03]

lgtm

a few comments below; feel free to ignore them.

https://codereview.chromium.org/874393007/diff/60001/BUILD.gn
File BUILD.gn (right):

https://codereview.chromium.org/874393007/diff/60001/BUILD.gn#newcode37
BUILD.gn:37: assert(host_os == "linux")
This is definitely simpler and an improvement.

https://codereview.chromium.org/874393007/diff/60001/BUILD.gn#newcode128
BUILD.gn:128: if (arm_fpu == "vfpv3") {
nit: I'd probably write lines 128 and 134 as 'else if' to make it a little more
obvious that these choices are mutually exclusive (though it's obviously not
actually necessary), and put a blank line between lines 124 and 125 to make it
clearer that these are two different sets of conditionals.

https://codereview.chromium.org/874393007/diff/60001/BUILD.gn#newcode142
BUILD.gn:142: defines += [
We only get into this branch when building mksnapshot (and its deps) in the host
toolchain, right?

It might be helpful to put a comment to that effect in here, something like:

# these defines are used in the ARM snapshot_toolchain.