70997f9a4e
The Tag_ABI_VFP_args build attribute controls the procedure call standard
used for floating point parameters on ARM. The values are:
0 - Base AAPCS (FP Parameters passed in Core (Integer) registers
1 - VFP AAPCS (FP Parameters passed in FP registers)
2 - Toolchain specific (Neither Base or VFP)
3 - Compatible with all (No use of floating point parameters)
If the Tag_ABI_VFP_args build attribute is missing it has an implicit value
of 0.
We use the attribute in two ways:
- Detect a clash in calling convention between Base, VFP and Toolchain.
we follow ld.bfd's lead and do not error if there is a clash between an
implicit Base AAPCS caused by a missing attribute. Many projects
including the hard-float (VFP AAPCS) version of glibc contain assembler
files that do not use floating point but do not have Tag_ABI_VFP_args.
- Set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD ELF header flag
for Base or VFP AAPCS respectively. This flag is used by some ELF
loaders.
References:
- Addenda to, and Errata in, the ABI for the ARM Architecture for
Tag_ABI_VFP_args
- Elf for the ARM Architecture for ELF header flags
Fixes PR36009
Differential Revision: https://reviews.llvm.org/D49993
llvm-svn: 338377
16 lines
365 B
ArmAsm
16 lines
365 B
ArmAsm
// REQUIRES: arm
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// RUN: llvm-mc -filetype=obj -triple=armv7a-none-linux-gnueabi %s -o %t.o
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// RUN: ld.lld -static %t.o -o %tout
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// RUN: llvm-readobj -file-headers %tout | FileCheck %s
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.syntax unified
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.text
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.globl _start
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_start:
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bx lr
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// CHECK: Flags [
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// CHECK-NEXT: 0x200
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// CHECK-NEXT: 0x1000000
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// CHECK-NEXT: 0x4000000
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// CHECK-NEXT: ]
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