mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-10-22 04:22:57 +02:00
9da3c40bfb
This is a fix for: https://llvm.org/bugs/show_bug.cgi?id=25900 If we think that an arithmetic right shift of a power of two is always a power of two, an sdiv gets wrongly converted to udiv. Differential Revision: http://reviews.llvm.org/D15827 llvm-svn: 256655
21 lines
573 B
LLVM
21 lines
573 B
LLVM
; RUN: opt -S -instcombine < %s | FileCheck %s
|
|
|
|
; https://llvm.org/bugs/show_bug.cgi?id=25900
|
|
; An arithmetic shift right of a power of two is not a power
|
|
; of two if the original value is the sign bit. Therefore,
|
|
; we can't transform the sdiv into a udiv.
|
|
|
|
define i32 @pr25900(i32 %d) {
|
|
%and = and i32 %d, -2147483648
|
|
; The next 3 lines prevent another fold from masking the bug.
|
|
%ext = zext i32 %and to i64
|
|
%or = or i64 %ext, 4294967296
|
|
%trunc = trunc i64 %or to i32
|
|
%ashr = ashr exact i32 %trunc, 31
|
|
%div = sdiv i32 4, %ashr
|
|
ret i32 %div
|
|
|
|
; CHECK: sdiv
|
|
}
|
|
|