}
}
+static XBT_ALWAYS_INLINE void* mc_translate_address_region(uintptr_t addr, simgrid::mc::Region* region)
+{
+ auto split = simgrid::mc::mmu::split(addr - region->start().address());
+ auto pageno = split.first;
+ auto offset = split.second;
+ const void* snapshot_page = region->get_chunks().page(pageno);
+ return (char*)snapshot_page + offset;
+}
+
+const void* Region::read(void* target, const void* addr, std::size_t size)
+{
+ xbt_assert(contain(simgrid::mc::remote(addr)), "Trying to read out of the region boundary.");
+
+ // Last byte of the region:
+ void* end = (char*)addr + size - 1;
+ if (simgrid::mc::mmu::same_chunk((std::uintptr_t)addr, (std::uintptr_t)end)) {
+ // The memory is contained in a single page:
+ return mc_translate_address_region((uintptr_t)addr, this);
+ }
+ // Otherwise, the memory spans several pages. Let's copy it all into the provided buffer
+ xbt_assert(target != nullptr, "Missing destination buffer for fragmented memory access");
+
+ // TODO, we assume the chunks are aligned to natural chunk boundaries.
+ // We should remove this assumption.
+
+ // Page of the last byte of the memory area:
+ size_t page_end = simgrid::mc::mmu::split((std::uintptr_t)end).first;
+
+ void* dest = target; // iterator in the buffer to where we should copy next
+
+ // Read each page:
+ while (simgrid::mc::mmu::split((std::uintptr_t)addr).first != page_end) {
+ void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
+ void* next_page = (void*)simgrid::mc::mmu::join(simgrid::mc::mmu::split((std::uintptr_t)addr).first + 1, 0);
+ size_t readable = (char*)next_page - (char*)addr;
+ memcpy(dest, snapshot_addr, readable);
+ addr = (char*)addr + readable;
+ dest = (char*)dest + readable;
+ size -= readable;
+ }
+
+ // Read the end:
+ void* snapshot_addr = mc_translate_address_region((uintptr_t)addr, this);
+ memcpy(dest, snapshot_addr, size);
+
+ return target;
+}
+
} // namespace mc
} // namespace simgrid
+
+/** Compare memory between snapshots (with known regions)
+ *
+ * @param addr1 Address in the first snapshot
+ * @param region1 Region of the address in the first snapshot
+ * @param addr2 Address in the second snapshot
+ * @param region2 Region of the address in the second snapshot
+ * @return same semantic as memcmp
+ */
+int MC_snapshot_region_memcmp(const void* addr1, simgrid::mc::Region* region1, const void* addr2,
+ simgrid::mc::Region* region2, size_t size)
+{
+ // Using alloca() for large allocations may trigger stack overflow:
+ // use malloc if the buffer is too big.
+ bool stack_alloc = size < 64;
+ void* buffer1a = stack_alloc ? alloca(size) : ::operator new(size);
+ void* buffer2a = stack_alloc ? alloca(size) : ::operator new(size);
+ const void* buffer1 = region1->read(buffer1a, addr1, size);
+ const void* buffer2 = region2->read(buffer2a, addr2, size);
+ int res;
+ if (buffer1 == buffer2)
+ res = 0;
+ else
+ res = memcmp(buffer1, buffer2, size);
+ if (not stack_alloc) {
+ ::operator delete(buffer1a);
+ ::operator delete(buffer2a);
+ }
+ return res;
+}
