HomePhabricator

Revert 1c021c64c "[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but…

Authored by hans on Oct 12 2020, 9:32 AM.

Description

Revert 1c021c64c "[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but as zext/trunc/self of SCEVUnknown"

While we indeed can't treat them as no-ops, i believe we can/should
do better than just modelling them as unknown. inttoptr story
is complicated, but for ptrtoint, it seems straight-forward
to model it just as a zext-or-trunc of unknown.

This may be important now that we track towards
making inttoptr/ptrtoint casts not no-op,
and towards preventing folding them into loads/etc
(see D88979/D88789/D88788)

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D88806

It caused the following assert during Chromium builds:

llvm/lib/IR/Constants.cpp:1868:
static llvm::Constant *llvm::ConstantExpr::getTrunc(llvm::Constant *, llvm::Type *, bool):
Assertion `C->getType()->isIntOrIntVectorTy() && "Trunc operand must be integer"' failed.

See code review for a link to a reproducer.

This reverts commit 1c021c64caef83cccb719c9bf0a2554faa6563af.