https://bugs.llvm.org/show_bug.cgi?id=50218
Bug ID: 50218
Summary: Failed to combine popcount(x) + popcount(x >> 32) to
popcountl(x)
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
int test(unsigned long x) {
return __builtin_popcount(x) + __builtin_popcount(x >> 32);
}
----------------------------------------
define i32 @src(i64 %0) {
%1:
%2 = trunc i64 %0 to i32
%3 = ctpop i32 %2
%4 = lshr i64 %0, 32
%5 = trunc i64 %4 to i32
%6 = ctpop i32 %5
%7 = add i32 %6, %3
ret i32 %7
}
=>
define i32 @tgt(i64 %0) {
%1:
%2 = ctpop i64 %0
%3 = trunc i64 %2 to i32
ret i32 %3
}
Transformation seems to be correct!
alive: https://alive2.llvm.org/ce/z/XYSuCb
codegen: https://godbolt.org/z/josqoYEed
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