What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
A near relative x86 CALL encodes a signed distance from the instruction after the call to its target, not the target’s absolute address. That creates a pattern an instruction-aware PE compressor could potentially exploit—but the available encoding and PE-format documentation does not show that any particular compressor misses savings or how many bytes it might save.
How a relative x86 CALL reaches its target
For the common near relative form, the instruction begins with opcode E8 and carries a signed displacement. Intel documents the 16-bit form as E8 cw and the 32-bit form as E8 cd; in 64-bit mode, the 32-bit displacement is sign-extended to 64 bits. Intel describes the target as a displacement relative to the next instruction. Intel Software Developer’s Manual, Volume 2A is the instruction-set reference.
As an Amazon Associate I earn from qualifying purchases.
For an E8 rel32 call, the opcode is followed by a four-byte signed displacement. The target calculation is:
target address = address after CALL + sign-extended displacement
#1 Best Overall
For example, if the instruction ends at address 0x1005 and its displacement is 0x2B, the target is 0x1030. A negative displacement reaches backward. The displacement is a distance, not an absolute address written into the instruction.
Not every CALL has a relative immediate
x86 also supports indirect near calls, encoded with FF /2 and a register or memory operand. In those forms, the call obtains its destination through that operand rather than the E8 relative-immediate encoding. A discussion of relative call displacements therefore applies to the relative forms, not every instruction whose mnemonic is CALL.
What changes when code is laid out differently?
The encoded displacement depends on the distance between the call and its target. If a linker, compiler, or other layout step moves one relative to the other, the distance—and potentially the operand bytes—changes. That is the property behind the compression idea: a compressor that understands instructions might identify, normalize, or predict relative operands instead of treating every byte as unrelated data.
That possibility is an inference from the encoding, not evidence of actual compression gains. Relative distances can vary with function layout, and a general-purpose compressor already works on byte patterns. Whether instruction-aware preprocessing helps depends on the compressor, the executable corpus, and the cost of any added decoding or processing.
Do not confuse object-file relocations with PE base relocations
Microsoft’s PE format documentation lists IMAGE_REL_I386_REL32 as a 32-bit relative displacement used for x86 branch and call instructions. This is an I386 object-file relocation type: it describes link-time relocation information, not a promise that each relative call in a linked PE image has an entry in its runtime base-relocation table. Microsoft’s PE Format documentation distinguishes the format’s relocation information; the object-file and loaded-image stages should not be conflated.
A relative call target is calculated from the call’s position, which makes that operand less dependent on a fixed load address than an absolute address embedded directly in the instruction. It does not mean the whole program is free of absolute references or that the executable needs no other relocation handling.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What evidence would establish a PE compression advantage?
The claim that a PE compressor “leaves money on the table” is a hypothesis unless tested against a defined baseline. A credible comparison would need at least:
Free tools Windows power users keep installed
One-click scans. No signup required.
- A representative corpus: identify the PE files, architectures, compiler and linker variations, and any exclusions.
- A clear baseline: name the general-purpose compressor and settings, and compare it with a defined instruction-aware preprocessing method.
- Comparable output sizes: report results on the same inputs, including whether headers, resources, and executable sections are included.
- Correctness checks: verify decompression reproduces the original files and that any executable transformations preserve the relevant relocation and loading behavior.
- Costs as well as size: report decompression or runtime overhead and the processing required to create the compressed output.
- Reproducibility: provide enough corpus and configuration detail for others to repeat the comparison.
The Intel instruction reference and Microsoft format documentation establish how the encoding and relocation type work; they do not provide a compressor comparison, corpus, or savings figure. Without those measurements, no byte count or percentage can responsibly be attached to the idea.
Where to verify the instruction details
Intel’s manuals index identifies Volume 2 as the instruction-set reference and reports the downloadable manuals at version 093; the index page was updated September 21, 2026. See Intel’s manuals page for the manuals and publication information.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
