https://bugs.llvm.org/show_bug.cgi?id=42848
Bug ID: 42848
Summary: Missed Optimization: redundant ternary expression not
removed
Product: new-bugs
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: jameshamm1...@gmail.com
CC: htmldevelo...@gmail.com, llvm-bugs@lists.llvm.org
Missed optimization on a ternary expression which has two equivalent output
paths.
Example code (https://godbolt.org/z/6dYE7d) compiled with clang (trunk,
currently 10.0.0) -Ofast -march=skylake
int f(int a, int b) {
return (a == b) ? (a + b) : (a + a);
}
produces
f(int, int): # @f(int, int)
lea ecx, [rsi + rdi]
lea eax, [rdi + rdi]
cmp edi, esi
cmove eax, ecx
ret
Since a == b, the code can be reduced to
int f(int a, int b) {
return (a == b) ? (a + a) : (a + a);
}
which produces the much shorter assembly
f(int, int): # @f(int, int)
lea eax, [rdi + rdi]
ret
This result is correct according to alive (https://rise4fun.com/Alive/Ozp)
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
