https://bugs.llvm.org/show_bug.cgi?id=34240
Bug ID: 34240
Summary: strange optimization for cos(cos(20)) with math.h but
not cmath
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: C++
Assignee: unassignedclangb...@nondot.org
Reporter: xax...@gmail.com
CC: dgre...@apple.com, llvm-bugs@lists.llvm.org
Recursive call with cos(cos(20)) in the body is reduced to no-op with cmath but
with math.h the generated code makes the recursive calls.
With only cos(20) both headers result in the generated code being a no-op.
#include <math.h>
void recurseTest(int level){
for(int i =0; i < 15; i++){
cos(cos(20));
recurseTest(level +1);
}
}
Strange behavior with math.h:
https://godbolt.org/g/y9gZW7
Desired behavior with cmath instead:
https://godbolt.org/g/rh9BMg
Desired behavior with math.h and only cos(20) not cos(cos(20))
https://godbolt.org/g/tn6EDg
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