Add a test-case for small profiled allocations

Validate that small allocations (i.e. those with `size <= SC_SMALL_MAXCLASS`)
which are sampled for profiling maintain the expected invariants even
though they now take up less space.

Makefile.in

@@ -256,6 +256,7 @@ TESTS_UNIT := \
 	$(srcroot)test/unit/prof_mdump.c \
 	$(srcroot)test/unit/prof_recent.c \
 	$(srcroot)test/unit/prof_reset.c \
+	$(srcroot)test/unit/prof_small.c \
 	$(srcroot)test/unit/prof_stats.c \
 	$(srcroot)test/unit/prof_tctx.c \
 	$(srcroot)test/unit/prof_thread_name.c \

test/unit/prof_small.c

@@ -0,0 +1,78 @@
+#include "test/jemalloc_test.h"
+
+static void assert_small_allocation_sampled(void *ptr, size_t size) {
+	assert_ptr_not_null(ptr, "Unexpected malloc failure");
+	assert_zu_le(size, SC_SMALL_MAXCLASS, "Unexpected large size class");
+	edata_t *edata = emap_edata_lookup(TSDN_NULL, &arena_emap_global, ptr);
+	assert_ptr_not_null(edata, "Unable to find edata for allocation");
+	expect_false(edata_slab_get(edata),
+	    "Sampled small allocations should not be placed on slabs");
+	expect_ptr_eq(edata_base_get(edata), ptr,
+	    "Sampled allocations should be page-aligned");
+	expect_zu_eq(edata_usize_get(edata), size,
+	    "Edata usize did not match requested size");
+	expect_zu_eq(edata_size_get(edata), PAGE_CEILING(size) + sz_large_pad,
+	    "Edata actual size was not a multiple of PAGE");
+	prof_tctx_t *prof_tctx = edata_prof_tctx_get(edata);
+	expect_ptr_not_null(prof_tctx, "Edata had null prof_tctx");
+	expect_ptr_not_null(prof_tctx->tdata,
+	    "Edata had null prof_tdata despite being sampled");
+}
+
+TEST_BEGIN(test_profile_small_allocations) {
+	test_skip_if(!config_prof);
+
+	for (szind_t index = 0; index < SC_NBINS; index++) {
+		size_t size = sz_index2size(index);
+		void *ptr = malloc(size);
+		assert_small_allocation_sampled(ptr, size);
+		free(ptr);
+	}
+}
+TEST_END
+
+TEST_BEGIN(test_profile_small_reallocations_growing) {
+	test_skip_if(!config_prof);
+
+	void *ptr = NULL;
+	for (szind_t index = 0; index < SC_NBINS; index++) {
+		size_t size = sz_index2size(index);
+		ptr = realloc(ptr, size);
+		assert_small_allocation_sampled(ptr, size);
+	}
+}
+TEST_END
+
+TEST_BEGIN(test_profile_small_reallocations_shrinking) {
+	test_skip_if(!config_prof);
+
+	void *ptr = NULL;
+	for (szind_t index = SC_NBINS; index-- > 0;) {
+		size_t size = sz_index2size(index);
+		ptr = realloc(ptr, size);
+		assert_small_allocation_sampled(ptr, size);
+	}
+}
+TEST_END
+
+TEST_BEGIN(test_profile_small_reallocations_same_size_class) {
+	test_skip_if(!config_prof);
+
+	for (szind_t index = 0; index < SC_NBINS; index++) {
+		size_t size = sz_index2size(index);
+		void *ptr = malloc(size);
+		assert_small_allocation_sampled(ptr, size);
+		ptr = realloc(ptr, size - 1);
+		assert_small_allocation_sampled(ptr, size);
+		free(ptr);
+	}
+}
+TEST_END
+
+int
+main(void) {
+	return test(test_profile_small_allocations,
+	    test_profile_small_reallocations_growing,
+	    test_profile_small_reallocations_shrinking,
+	    test_profile_small_reallocations_same_size_class);
+}

test/unit/prof_small.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+if [ "x${enable_prof}" = "x1" ] ; then
+  export MALLOC_CONF="prof:true,lg_prof_sample:0"
+fi
+