https://bugs.llvm.org/show_bug.cgi?id=38619
Bug ID: 38619
Summary: clang miscompiles with "-newgvn" at -O2 on valid code
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: LLVM Codegen
Assignee: unassignedclangbugs at nondot.org
Reporter: helloqirun at gmail.com
CC: llvm-bugs at lists.llvm.org
It also affects clang-5.0 and clang-6.0.
clang-r312400: first working build
clang-r312401: next failing build
$ clang abc.c ; ./a.out
9
$ clang-4.0 -mllvm -enable-newgvn -O2 abc.c ; ./a.out
9
$ clang-5.0 -mllvm -enable-newgvn -O2 abc.c ; ./a.out
0
$ clang-trunk -mllvm -enable-newgvn -O2 abc.c ; ./a.out
0
$ clang-trunk -v
clang version 8.0.0 (trunk 340070)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
$ cat abc.c
void printf();
int a;
short b, c, d, f;
char e;
int g() {
d = 0;
for (;; ++d) {
b = f = d * a;
e = f % 0x95216DC9;
c |= e;
if (d)
return 3;
for (; a < 8; a = 9)
;
}
}
int main() {
g();
printf("%d\n", e);
}
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