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Incorrect code generation ACOMPE 6.21 with -O1

Nekoneko

In a little piece of test code, I have the following:

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int main(void)
{
osStatus_t osStat;
HAL_Init();
osStat = osKernelInitialize();
if (osStat != osOK)
{
NVIC_SystemReset();
}
while(true);
return 0;
}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Very simple.

When compiling with -O0, the disassembly for the relevant part looks like:

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main:
.Lfunc_begin1:
.loc 2 31 0 @ ../main.c:31:0
.fnstart
.cfi_startproc
@ %bb.0:
.save {r7, lr}
push {r7, lr}
.cfi_def_cfa_offset 8
.cfi_offset lr, -4
.cfi_offset r7, -8
.pad #8
sub sp, #8
.cfi_def_cfa_offset 16
movs r0, #0
str r0, [sp, #4]
.Ltmp1:
.loc 2 34 2 prologue_end @ ../main.c:34:2
bl HAL_Init
.loc 2 36 11 @ ../main.c:36:11
bl osKernelInitialize
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

But with -O1 or higher optimization:

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main:
.Lfunc_begin1:
.fnstart
.cfi_startproc
@ %bb.0:
.loc 2 34 2 prologue_end @ ../main.c:34:2
bl HAL_Init
.Ltmp1:
.loc 2 36 11 @ ../main.c:36:11
bl osKernelInitialize
.Ltmp2:
@DEBUG_VALUE: main:osStat <- undef
.loc 2 39 3 @ ../main.c:39:3
bl _ZL18__NVIC_SystemResetv
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

All of a sudden, the comparison after the call to osKernelInitialize is gone...

The while(true) is only there temporarily, and I am aware that it can be optimized away as it undefined behavior, but I do expect the compiler to actually handle the preceding if-statement properly first.

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