https://bugs.llvm.org/show_bug.cgi?id=33238
Bug ID: 33238
Summary: Wrong isl ast schedule generated
Product: Polly
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Other
Assignee: polly-...@googlegroups.com
Reporter: huih...@codeaurora.org
CC: llvm-bugs@lists.llvm.org
Created attachment 18547
--> https://bugs.llvm.org/attachment.cgi?id=18547&action=edit
test input
Attaching the test.ll as test input
Run command "opt -polly-codegen -S test.ll -debug"
Polly produce the isl ast schedule of:
{
if (p_0 >= 3) {
for (int c0 = 0; c0 < (p_0 + 2) / 4; c0 += 1) {
Stmt0(c0);
if (p_0 >= 4 * c0 + 3) {
Stmt2(c0);
if (p_0 >= 4 * c0 + 4) {
Stmt4(c0);
if (p_0 >= 4 * c0 + 5)
Stmt6(c0);
}
}
}
if ((p_0 - 1) % 4 == 0) {
Stmt7();
} else if (p_0 % 4 == 0) {
Stmt5();
} else if ((p_0 + 1) % 4 == 0) {
Stmt3();
}
} else {
Stmt0(0);
}
Stmt1();
}
else
{ /* original code */ }
However, the correct schedule should be:
{
if (p_0 >= 3) {
for (int c0 = 0; c0 < (p_0 + 2) / 4; c0 += 1) {
Stmt0(c0);
if (p_0 >= 4 * c0 + 3) {
Stmt2(c0);
if (p_0 >= 4 * c0 + 4) {
Stmt4(c0);
if (p_0 >= 4 * c0 + 5)
Stmt6(c0);
}
}
}
if ((p_0 - 1) % 4 == 0) {
Stmt7();
} else if (p_0 % 4 == 0) {
Stmt5();
} else if ((p_0 + 1) % 4 == 0) {
Stmt3();
}
} else {
Stmt0(0);
}
if((n <= 2) || ((n - 2)%4 == 0))
Stmt1();
}
else
{ /* original code */ }
Notice that for Statement Stmt1(), Polly produce universe domain, Stmt1 is
being executed unconditionally. However, if going through the basic blocks of
the input test.ll file, Stmt1 will only be executed under condition "((n <= 2)
|| ((n - 2)%4 == 0))"
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