https://bugs.llvm.org/show_bug.cgi?id=51092
Bug ID: 51092
Summary: Duplicate select instruction causing one use check
failure
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: llvm-...@redking.me.uk
CC: lebedev...@gmail.com, llvm-bugs@lists.llvm.org,
nikita....@gmail.com, spatel+l...@rotateright.com
https://godbolt.org/z/4avqKsT4x
struct PayLoad
{
unsigned short data[3];
};
void sort(PayLoad* pData, int lo, int hi, int ishi)
{
if (ishi)
{
pData->data[hi]++;
}
else
{
pData->data[lo]++;
}
}
%struct.PayLoad = type { [3 x i16] }
define void @_Z4sortP7PayLoadiii(%struct.PayLoad* nocapture %0, i32 %1, i32 %2,
i32 %3) {
%5 = icmp eq i32 %3, 0
%6 = sext i32 %1 to i64
%7 = getelementptr inbounds %struct.PayLoad, %struct.PayLoad* %0, i64 0, i32
0, i64 %6
%8 = sext i32 %2 to i64
%9 = getelementptr inbounds %struct.PayLoad, %struct.PayLoad* %0, i64 0, i32
0, i64 %8
%10 = select i1 %5, i16* %7, i16* %9
%11 = select i1 %5, i16* %7, i16* %9
%12 = load i16, i16* %10, align 2, !tbaa !3
%13 = add i16 %12, 1
store i16 %13, i16* %11, align 2, !tbaa !3
ret void
}
I'm currently investigating supporting select(gep,gep) folding for geps with >
2 operands, but we fail the one use check on this reduced test case as we end
up with the same select instruction twice which never get merged.
Should these be merged or not?
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