Heap stats not reported correctly with IAR in NUMAKER_PFM_NUC472

[andresag01]

While trying to profile the heap usage by one of the sample applications I used the heap_stats feature from mbed OS as described in this website. Specifically, I ran the following code:

#include "mbed.h"
#include "mbed_stats.h"
#include "cmsis_os.h"

int main(void)
{
	mbed_stats_heap_t heap_stats;

	printf("Starting head stats example\r\n");
	printf("Starting stack stats example\r\n");

	osThreadId main_id = osThreadGetId();

	osEvent info;
	info = _osThreadGetInfo(main_id, osThreadInfoStackSize);
	if (info.status != osOK) {
		printf("Could not get stack size\r\n");
	}
	uint32_t stack_size = (uint32_t)info.value.v;
	info = _osThreadGetInfo(main_id, osThreadInfoStackMax);
	if(info.status != osOK) {
		printf("Could not get max stack\r\n");
	}
	uint32_t max_stack = (uint32_t)info.value.v;
	printf("Stack used %li of %li bytes\r\n", max_stack, stack_size);

	void *allocation = malloc(1000);
	printf("Freeing 1000 bytes\r\n");

	mbed_stats_heap_get(&heap_stats);
	printf("Current heap: %lu\r\n", heap_stats.current_size);
	printf("Max heap size: %lu\r\n", heap_stats.max_size);

	free(allocation);

	mbed_stats_heap_get(&heap_stats);
	printf("Current heap after: %lu\r\n", heap_stats.current_size);
	printf("Max heap size after: %lu\r\n", heap_stats.max_size);

	return 0;
}

Then I compiled using the command:

mbed compile -t IAR -m NUMAKER_PFM_NUC472 -DMBED_HEAP_STATS_ENABLED=1 -DMBED_STACK_STATS_ENABLED=1 -c

And observed the following output in the serial terminal:

Starting head stats example
Starting stack stats example
Stack used 392 of 4096 bytes
Freeing 1000 bytes
Current heap: 0
Max heap size: 0
Current heap after: 0
Max heap size after: 0

However, this output is not accurate as my program consumes at least 1KB of heap memory with that call to malloc(). Note that the statistics reported seem correct when compiling with ARM and GCC_ARM.

Description

• Type: Bug
• Priority: Major

---

Bug

Target
NUMAKER_PFM_NUC472

Toolchain:
IAR

Toolchain version:
IAR ANSI C/C++ Compiler V7.70.1.11437/W32 for ARM

mbed-cli version:
1.0.0

meed-os sha:
#bcf7085d85b2811b5d68bdda192c754eadfb8f88

Expected behavior
Heap stats should be reported correctly.

Actual behavior
Heap usage is always reported as 0 bytes.

Steps to reproduce
Compile (using IAR) and run the program pasted at the beginning of this report on the NUMAKER_PFM_NUC472.

[0xc0170]

Is this just one target specific?

cc @c1728p9

[c1728p9]

Heap stats never worked for IAR, since there isn't a way to hook their functions

[deepikabhavnani]

Resolved in PR #4965

[ciarmcom]

ARM Internal Ref: MBOTRIAGE-370