[Bug gas/28603] New: Incorrect branch offset from the start of a function after enable LTO

[sen2403 at hotmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28603

            Bug ID: 28603
           Summary: Incorrect branch offset from the start of a function
                    after enable LTO
           Product: binutils
           Version: 2.35.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gas
          Assignee: unassigned at sourceware dot org
          Reporter: sen2403 at hotmail dot com
  Target Milestone: ---

After enabling LTO, the branch offset is incorrect in SVC_Handler of a
FreeRTOS+CM4 project.

Here is the simple code and assembler output. The branch address is offset 2
bytes from foo function and bypass the push instruction. It causes problem when
returning from foo function.
==========================================================
void SVC_Handler(void)
{
    __asm volatile (
                    "    cpsid i    \n"
                    "    blx   foo  \n"
                    "    cpsie i    \n"
                /* ..... code removed ... */
}

000010b0 <SVC_Handler>:
000010b0:    b672         cpsid   i
000010b2:    f7ff f892    bl  000001da <foo+0x2>    <<<---- this causes problem
000010b6:    b662         cpsie   i


000001d8: <foo>:
000001d8:    e92d 4178    stmdb    sp!, {r3, r4, r5, r6, r8, lr}
000001dc:    f001 f8e8    bl  000013b0 <__foo2_veneer>
==========================================================

If I change the blx to bl or insert push/pop, the result will be OK.
==========================================================
void SVC_Handler(void)
{
    __asm volatile (
                    "    cpsid i    \n"
                    "    bl    foo  \n"
                    "    cpsie i    \n"
                /* ..... code removed ... */
}

000010b0 <SVC_Handler>:
000010b0:    b672         cpsid   i
000010b2:    f7ff f892    bl  000001d8 <foo>
000010b6:    b662         cpsie   i


000001d8: <foo>:
000001d8:    e92d 4178    stmdb    sp!, {r3, r4, r5, r6, r8, lr}
000001dc:    f001 f8e8    bl  000013b0 <__foo2_veneer>
==========================================================

void SVC_Handler(void)
{
    __asm volatile (
                    "    cpsid i    \n"
                    "    push  {lr} \n"
                    "    blx   foo  \n"
                    "    pop   {lr} \n"
                    "    cpsie i    \n"
                /* ..... code removed ... */
}

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