http://llvm.org/bugs/show_bug.cgi?id=14314
Bug #: 14314
Summary: Codegen for atomicrmw sub i64 is broken for x86-32
Product: new-bugs
Version: trunk
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 9522
--> http://llvm.org/bugs/attachment.cgi?id=9522
Testcase
The following program should should print -1.
#include <stdio.h>
#include <stdint.h>
int64_t atomicSub(int64_t *a, int64_t b) {
return __sync_fetch_and_sub(a, b);
}
int main(int argc, char **argv) {
int64_t a = 0;
atomicSub(&a, 1);
printf("a = %lli\n", a);
return 0;
}
clang on x86-64 and gcc on all architectures compile the program correctly.
clang on x86-32 prints 1. The last working revision of clang was 164820. The
bug first appears in 164821 after a checkin from Michael Liao titled, "Re-work
X86 code generation of atomic ops with spin-loop."
I have attached LLVM IR for the test case. The LLVM IR is generated correctly
in both 164820 and 164821.
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