Jonas Maebe suggested that I try Dr Memory to track down a possible heap corruption in one of my test programs.

This has led to what I think deserves it own discussion thread.

I ran a lazarus 1.2.4/fpc 2.6.4 compiled programs on Windows 8.1 x64 compilied with Dwarf2 (-dw2)
and HeapTrc On, Range Check ON (-Cr), Verify Method On (-CR)

The minimal example is just creating a simple lazarus application with a single unpopulated form. Compile. Run.

Attached is the results file and the sample minimal app for verification.

Command line for Dr Memory: C:\pdev\rpztestminimum>drmemory.exe -- rpztestminimum.exe <enter>

Heaptrc when turned on with CMEM commented out reports no heap errors.

What I find suprising is the number of ERRORS that Dr Memory discovered on a raw, naked, simple lazarus application.

Anybody have greater experience with Dr Memory to know what errors are actually real and which errors are valid in the latests releases of lazarus/fpc.

Cheers,

marco

mark diener wrote

Anybody have greater experience with Dr Memory to know what errors are actually real and which errors are valid in the latests releases of lazarus/fpc.

* Not actual errors:

Error #1: UNADDRESSABLE ACCESS: reading 0x04c491c3-0x04c491c4 1 byte(s) within 0x04c491c0-0x04c491c4
# 0 FPC_PCHAR_TO_SHORTSTR [C:/pdev/ rpztestminimum//rpztestminimum.lpr:21]

Error #2: UNADDRESSABLE ACCESS: reading 0x0508cf61-0x0508cf64 3 byte(s) within 0x0508cf60-0x0508cf64
# 0 SYSTEM_SMALLFORWARDMOVE_3

Error #3: UNADDRESSABLE ACCESS: reading 0x050ee701-0x050ee704 3 byte(s) within 0x050ee700-0x050ee704
# 0 SYSUTILS_STRSCAN$PCHAR$CHAR$
$PCHAR [C:/pdev/ rpztestminimum//rpztestminimum.lpr:21]

* No idea, but probably not real errors since otherwise the program would crash:

Error #4: UNADDRESSABLE ACCESS: writing 0x00000020-0x00000024 4 byte(s) within 0x00000020-0x04c5c950
# 0 system call NtUserBuildPropList parameter #1

Error #5: UNADDRESSABLE ACCESS: writing 0x00000020-0x00000024 4 byte(s) within 0x00000020-0x04c5c950
# 0 system call NtUserBuildPropList parameter #1

Error #6: UNADDRESSABLE ACCESS: writing 0x00000020-0x00000024 4 byte(s) within 0x00000020-0x04c5ceb0
# 0 system call NtUserBuildPropList parameter #1

Error #7: UNADDRESSABLE ACCESS: writing 0x00000020-0x00000024 4 byte(s) within 0x00000020-0x04c5ceb0
# 0 system call NtUserBuildPropList parameter #1

* Probably not an actual error (see my mail in the other thread)

Error #8: POSSIBLE LEAK 64 direct bytes 0x04c489d0-0x04c48a10 + 0 indirect bytes
# 0 replace_RtlAllocateHeap [d: \drmemory_package\common\alloc_replace.c:3076]

You'll have to ask help on the Dr Memory mailing list regarding errors #4 - #7. For the false positives #1 - #3 and #8 (and similar ones to #8), you'll have to create a suppression file: http://www.drmemory.org/docs/page_suppress.html

Jonas