HomePhabricator

[DAGCombiner] fold assertzexts separated by trunc

Authored by spatel on Sep 18 2017, 3:05 PM.

Description

[DAGCombiner] fold assertzexts separated by trunc

If we have an AssertZext of a truncated value that has already been AssertZext'ed,
we can assert on the wider source op to improve the zext-y knowledge:
assert (trunc (assert X, i8) to iN), i1 --> trunc (assert X, i1) to iN

This moves a fold from being Mips-specific to general combining, and x86 shows
improvements.

Differential Revision: https://reviews.llvm.org/D37017

llvm-svn: 313577

Details

Committed
spatelSep 18 2017, 3:05 PM
Differential Revision
D37017: [DAGCombiner] fold assertzexts separated by trunc
Parents
rG1468677cbe9a: Fix failing ASAN test
Branches
Unknown
Tags
Unknown