https://bugs.llvm.org/show_bug.cgi?id=38450
Bug ID: 38450
Summary: cmp+store is not optimized to an unconditional store
Product: new-bugs
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: gonzalob...@gmail.com
CC: chandl...@gmail.com, hfin...@anl.gov,
llvm-bugs@lists.llvm.org, llvm-...@redking.me.uk,
spatel+l...@rotateright.com
See https://godbolt.org/g/5W5q2K , the following LLVM-IR:
define void @foo(i32* noalias nocapture dereferenceable(4) %x) {
start:
%0 = load i32, i32* %x, align 4
%1 = icmp eq i32 %0, 0
br i1 %1, label %bb2, label %bb1
bb1:
store i32 0, i32* %x, align 4
br label %bb2
bb2:
ret void
}
does not optimize to anything better with opt -O3. Using llc, it generates the
following x86_64 assembly code (https://godbolt.org/g/RX81Sn):
cmpl $0, (%rdi)
je .LBB0_2
movl $0, (%rdi)
.LBB0_2:
retq
I would expect this to just generate "movl $0, (%rdi); retq".
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