https://bugs.llvm.org/show_bug.cgi?id=51178
Bug ID: 51178
Summary: support runtime loop unroll with pointer type
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: Loop Optimizer
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
The loop unroll pass does not support runtime loop unroll with pointer type.
Let's see a example.
declare i32 @foo(i8 *)
define void @test(i8* %s, i64 %a) {
entry:
%s.addr.a = getelementptr i8, i8* %s, i64 %a
br label %while.body.us
while.body.us:
%s.addr = phi i8* [ %incdec.ptr, %while.body.us ], [ %s, %entry ]
%incdec.ptr = getelementptr inbounds i8, i8* %s.addr, i64 1
%incdec.val = load i8, i8* %s.addr, align 1
%cmp1 = icmp eq i8 %incdec.val, 10
br i1 %cmp1, label %return.loopexit, label %while.body.us
return.loopexit:
ret void
}
As you can see, the iv's instruction is getelementptr and the pass fails to
runtime unroll the loop with the iv. You can reproduce it with below command.
opt -loop-unroll -unroll-runtime above_ir_code_file.ll -S -o -
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