[DAGCombiner] Improve zextload optimization.
Summary:
Don't fold
(zext (and (load x), cst)) -> (and (zextload x), (zext cst))
if
(and (load x) cst)
will match as a zextload already and has additional users.
For example, the following IR:
%load = load i32, i32* %ptr, align 8
%load16 = and i32 %load, 65535
%load64 = zext i32 %load16 to i64
store i32 %load16, i32* %dst1, align 4
store i64 %load64, i64* %dst2, align 8
used to produce the following aarch64 code:
ldr w8, [x0]
and w9, w8, #0xffff
and x8, x8, #0xffff
str w9, [x1]
str x8, [x2]
but with this change produces the following aarch64 code:
ldrh w8, [x0]
str w8, [x1]
str x8, [x2]
Reviewers: resistor, mcrosier
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14340
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252789 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed