0f46e31cfb
As part of the migration to ptradd (https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699), we need to change the representation of the `inrange` attribute, which is used for vtable splitting. Currently, inrange is specified as follows: ``` getelementptr inbounds ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, inrange i32 1, i64 2) ``` The `inrange` is placed on a GEP index, and all accesses must be "in range" of that index. The new representation is as follows: ``` getelementptr inbounds inrange(-16, 16) ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, i32 1, i64 2) ``` This specifies which offsets are "in range" of the GEP result. The new representation will continue working when canonicalizing to ptradd representation: ``` getelementptr inbounds inrange(-16, 16) (i8, ptr @vt, i64 48) ``` The inrange offsets are relative to the return value of the GEP. An alternative design could make them relative to the source pointer instead. The result-relative format was chosen on the off-chance that we want to extend support to non-constant GEPs in the future, in which case this variant is more expressive. This implementation "upgrades" the old inrange representation in bitcode by simply dropping it. This is a very niche feature, and I don't think trying to upgrade it is worthwhile. Let me know if you disagree.
32 lines
1.1 KiB
LLVM
32 lines
1.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
|
|
; RUN: opt -passes=instcombine -S -o - %s | FileCheck %s
|
|
; Tests that we preserve the inrange attribute on indices where possible.
|
|
|
|
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
|
|
target triple = "x86_64-unknown-linux-gnu"
|
|
|
|
%struct.A = type { ptr }
|
|
|
|
@vt = external global [3 x ptr]
|
|
|
|
define ptr @f0() {
|
|
; CHECK-LABEL: @f0(
|
|
; CHECK-NEXT: ret ptr getelementptr inbounds inrange(-16, 8) ([3 x ptr], ptr @vt, i64 0, i64 2)
|
|
;
|
|
ret ptr getelementptr (ptr, ptr getelementptr inbounds inrange(-8, 16) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 1)
|
|
}
|
|
|
|
define ptr @f1() {
|
|
; CHECK-LABEL: @f1(
|
|
; CHECK-NEXT: ret ptr getelementptr inbounds inrange(-8, 0) ([3 x ptr], ptr @vt, i64 0, i64 2)
|
|
;
|
|
ret ptr getelementptr (ptr, ptr getelementptr inbounds inrange(0, 8) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 1)
|
|
}
|
|
|
|
define ptr @f2() {
|
|
; CHECK-LABEL: @f2(
|
|
; CHECK-NEXT: ret ptr getelementptr inrange(-24, -16) ([3 x ptr], ptr @vt, i64 1, i64 1)
|
|
;
|
|
ret ptr getelementptr (ptr, ptr getelementptr inbounds inrange(0, 8) ([3 x ptr], ptr @vt, i64 0, i64 1), i64 3)
|
|
}
|