https://bugs.llvm.org/show_bug.cgi?id=49306
Bug ID: 49306
Summary: Loop-interchange : Some triangular loop nests are
interchanged
Product: tools
Version: 11.0
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: opt
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
$ clang -Os -mllvm -enable-loopinterchange=true traingular_fail.c && ./a.out
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
$ clang -Os -mllvm -enable-loopinterchange=false triangular_fail.c && ./a.out
0 2 7 83 0 0 9 43 0 0 0 0 0 0 0 0
$ cat triangular_fail.c
#include <stdio.h>
int foo() {
int A[4][4] = {{ 0, 0, 0, 0},
{ 0, 0, 0, 0},
{ 0, 0, 0, 0},
{ 0, 0, 0, 0}};
int B[4][4] = {{ 16, 2, 7, 83},
{ 35, 8, 9, 43},
{ 47, 123, 32, 0},
{ 21, 11, 19, 29}};
for (int i = 0; i < 4; ++i)
for (int j = 0; j < i; ++j)
A[j][i] = B[j][i];
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; j++)
printf("%d ", A[i][j]);
printf("\n");
return 0;
}
int main() {
foo();
return 0;
}
LoopInterchange does not detect the issue with the operation `j<i` in the inner
loop, thus, breaking the program correctness.
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
