https://sourceware.org/bugzilla/show_bug.cgi?id=27066
Bug ID: 27066
Summary: [ARM] Unaligned LDRD instruction
Product: binutils
Version: 2.35.1
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: gas
Assignee: unassigned at sourceware dot org
Reporter: kordalski.wojciech at gmail dot com
Target Milestone: ---
Created attachment 13049
--> https://sourceware.org/bugzilla/attachment.cgi?id=13049&action=edit
The minimal example
During research of ARM Cortex-M3-based processor for our master thesis, we
found a bug (using a tool that generates random-but-correct sequences of
assembly instructions).
Minimal example:
.syntax unified
.cpu cortex-m3
.thumb
.align 2
.type f1, %function
.thumb_func
f1:
nop.n
ldrd.w r0, r1, data
.align 4
data:
.word 42
.word 77
The code is assembled without any warning or error message using command:
arm-none-eabi-as -o test.o test.s -mcpu=cortex-m3
However, the ARMv7-M Architecture Reference Manual states:
For the M profile, the PC value must be word-aligned, otherwise the
behavior of the instruction is UNPREDICTABLE.
(Section A7.7.51 LDRD (literal), page A7-259)
The ARMv7-M Architecture Reference Manual can be downloaded from:
https://static.docs.arm.com/ddi0403/ed/DDI0403E_d_armv7m_arm.pdf
Expected behavior: the assembler should print a warning or error message
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