https://bugs.llvm.org/show_bug.cgi?id=41720
Bug ID: 41720
Summary: loop-vectorize produces wrong code with "opt -gvn
-licm -loop-rotate -loop-vectorize"
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: csz...@163.com
CC: llvm-bugs@lists.llvm.org
Created attachment 21880
--> https://bugs.llvm.org/attachment.cgi?id=21880&action=edit
.bc file of the source code
$clang -v
clang version 9.0.0 (trunk 355281)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm/build4/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$clang -O3 -c -emit-llvm -mllvm -disable-llvm-optzns small.c
$clang small.bc -o small1.out && ./small1.out
9
$opt -gvn -licm -loop-rotate -loop-vectorize small.bc -o small-opt.bc
$clang small-opt.bc -o small2.out && ./small2.out
15
without loop-vectorize, the result is correct.
$opt -gvn -licm -loop-rotate small.bc -o small-opt1.bc
$clang small-opt1.bc -o small3.out && ./small3.out
9
------------------------------------
#include<stdio.h>
int a=0;
int d() {
int e = 2;
for (a = 0; a <= 8; a++)
;
return e;
}
void main() {
int f = 0;
d();
printf("%d\n",a);
}
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