Skip to content

[ARM][KCFI] Fix bundle sizes to reflect worst-case expansion #164917

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 25, 2025
+7 −5
Merged

[ARM][KCFI] Fix bundle sizes to reflect worst-case expansion #164917

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 7 additions & 5 deletions llvm/lib/Target/ARM/ARMInstrInfo.td
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6546,23 +6546,25 @@ def KCFI_CHECK_ARM
: PseudoInst<(outs), (ins GPR:$ptr, i32imm:$type), NoItinerary, []>,
Sched<[]>,
Requires<[IsARM]> {
let Size = 28; // 7 instructions (bic, ldr, 4x eor, beq, udf)
let Size = 40; // worst-case 10 instructions @ 4 bytes each
// (push, bic, ldr, 4x eor, pop, beq, udf)
}

def KCFI_CHECK_Thumb2
: PseudoInst<(outs), (ins GPR:$ptr, i32imm:$type), NoItinerary, []>,
Sched<[]>,
Requires<[IsThumb2]> {
let Size =
32; // worst-case 9 instructions (push, bic, ldr, 4x eor, pop, beq.w, udf)
let Size = 34; // worst-case (push.w[2], bic[4], ldr[4], 4x eor[16], pop.w[2],
// beq.w[4], udf[2])
}

def KCFI_CHECK_Thumb1
: PseudoInst<(outs), (ins GPR:$ptr, i32imm:$type), NoItinerary, []>,
Sched<[]>,
Requires<[IsThumb1Only]> {
let Size = 50; // worst-case 25 instructions (pushes, bic helper, type
// building, cmp, pops)
let Size = 38; // worst-case 19 instructions @ 2 bytes each
// (2x push, 3x bic-helper, subs+ldr, 13x type-building, cmp,
// 2x pop, beq, bkpt)
}

//===----------------------------------------------------------------------===//
Expand Down