[Patch, ARM]Update GCC to generate Tag_ABI_HardFP_use per the latest EABI doc

[Terry Guo]

Hi there,

According to the latest EABI at
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0045d/IHI0045D_ABI_adden
da.pdf, the new definition of Tag_ABI_HardFP_use is as below:

Tag_ABI_HardFP_use, (=27), uleb128
0 The user intended that FP use should be implied by Tag_FP_arch
1 The user intended this code to execute on the single-precision variant
 derived from Tag_FP_arch
2 Reserved
3 The user intended that FP use should be implied by Tag_FP_arch
 (Note: This is a deprecated duplicate of the default encoded by 0)

The attached patch intends to update gcc to conform this definition. Tested
with GCC regression test, no regressions. Is it OK?

BR,
Terry

2015-01-14  Terry Guo  <terry....@arm.com>

           * config/arm/arm.c (arm_file_start): Update the assignment of
Tag_ABI_HardFP_use.
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 0ec526b..378bed9 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -25576,7 +25576,13 @@ arm_file_start (void)
          if (arm_fpu_desc->model == ARM_FP_MODEL_VFP)
            {
              if (TARGET_HARD_FLOAT)
-               arm_emit_eabi_attribute ("Tag_ABI_HardFP_use", 27, 3);
+               {
+                 if (TARGET_VFP_SINGLE)
+                   arm_emit_eabi_attribute ("Tag_ABI_HardFP_use", 27, 1);
+                 else
+                   arm_emit_eabi_attribute ("Tag_ABI_HardFP_use", 27, 0);
+               }
+
              if (TARGET_HARD_FLOAT_ABI)
                arm_emit_eabi_attribute ("Tag_ABI_VFP_args", 28, 1);
            }