Version: refs/heads/master@{#429543} (56.0.2909.0)
OS: Linux

What steps will reproduce the problem?
(1) gn gen out_arm --args="target_cpu=\"arm\""
(2) ninja -C out_arm/ -v v8
(3) Analyze the log

What is the expected output?
Host should be built with: -DUSE_EABI_HARDFLOAT=1 and -DCAN_USE_NEON
Target should be built with: -mfloat-abi=hard and -mfpu=neon

What do you see instead?
Host is built with: -DUSE_EABI_HARDFLOAT=0
Target is built with: -mfloat-abi=hard and -mfpu=neon

Please use labels and text to provide additional information.
Introduced by the following two CLs:
https://codereview.chromium.org/2187563004 (neon)
https://codereview.chromium.org/2182473002 (float_abi)

I think this makes the v8 snapshot data be built with different float configuration than v8. I'm experiencing issues with (at least) Math.pow(...) due to this and explicitly specifying arm_float_abi="hard" helps resolving that.

In an attempt to see where the problem comes from I added this code to build/config/arm.gni:
  print("arm_float_abi : ", arm_float_abi)
  print("arm_use_neon  : ", arm_use_neon)
  print("current_cpu   : ", current_cpu)
  print("v8_current_cpu: ", v8_current_cpu)
  print("--")
  assert(arm_float_abi != "softfp")

This is the output I get from gn:
arm_float_abi :  hard
arm_use_neon  :  true
current_cpu   :  arm
v8_current_cpu:  arm
--
arm_float_abi :  softfp
arm_use_neon  :  false
current_cpu   :  x86
v8_current_cpu:  arm
--
ERROR at //build/config/arm.gni:108:3: Assertion failed.
  assert(arm_float_abi != "softfp")
  ^-----
See //v8/BUILD.gn:6:1: whence it was imported.
import("//build/config/arm.gni")
^------------------------------
See //BUILD.gn:1018:9: which caused the file to be included.
        "//v8:v8_shell($v8_snapshot_toolchain)",
        ^--------------------------------------