Add heaptrack support (#25257)

This PR, courtesy of @NagyZoltanPeter
(https://github.com/waku-org/nwaku/pull/3522) adds the ability to track
memory allocations in a program suitable for use with
[heaptrack](https://github.com/KDE/heaptrack).

By passing `-d:heaptrack --debugger:native` to compilation, calls to
heaptrack will be injected when memory is being allocated and released -
unlike `-d:useMalloc` this strategy also works with `refc` and the
default memory pool.

See https://github.com/KDE/heaptrack for usage examples. The resulting
binary needs to be run with `heaptrack` and with the shared
`libheaptrack_preload.so` in the `LD_LIBRARY_PATH`.

doc/nimc.md

@@ -580,6 +580,8 @@ Define                   Effect
                          Currently only clang and vcc.
 `strip`                  Strip debug symbols added by the backend compiler from
                          the executable.
+`heaptrack`              Track memory allocations using
+                         [heaptrack](https://github.com/KDE/heaptrack)
 ======================   =========================================================
 
 

lib/system/alloc.nim

@@ -837,6 +837,15 @@ when defined(gcDestructors):
       dec maxIters
       if it == nil: break
 
+when defined(heaptrack):
+  const heaptrackLib =
+    when defined(heaptrack_inject):
+      "libheaptrack_inject.so"
+    else:
+      "libheaptrack_preload.so"
+  proc heaptrack_malloc(a: pointer, size: int) {.cdecl, importc, dynlib: heaptrackLib.}
+  proc heaptrack_free(a: pointer) {.cdecl, importc, dynlib: heaptrackLib.}
+
 proc rawAlloc(a: var MemRegion, requestedSize: int): pointer =
   when defined(nimTypeNames):
     inc(a.allocCounter)
@@ -959,6 +968,8 @@ proc rawAlloc(a: var MemRegion, requestedSize: int): pointer =
   sysAssert(isAccessible(a, result), "rawAlloc 14")
   sysAssert(allocInv(a), "rawAlloc: end")
   when logAlloc: cprintf("var pointer_%p = alloc(%ld) # %p\n", result, requestedSize, addr a)
+  when defined(heaptrack):
+    heaptrack_malloc(result, requestedSize)
 
 proc rawAlloc0(a: var MemRegion, requestedSize: int): pointer =
   result = rawAlloc(a, requestedSize)
@@ -967,6 +978,8 @@ proc rawAlloc0(a: var MemRegion, requestedSize: int): pointer =
 proc rawDealloc(a: var MemRegion, p: pointer) =
   when defined(nimTypeNames):
     inc(a.deallocCounter)
+  when defined(heaptrack):
+    heaptrack_free(p)
   #sysAssert(isAllocatedPtr(a, p), "rawDealloc: no allocated pointer")
   sysAssert(allocInv(a), "rawDealloc: begin")
   var c = pageAddr(p)