https://bugs.llvm.org/show_bug.cgi?id=38683
Bug ID: 38683
Summary: [NewGVN] Running NewGVN twice back-to-back discovers
additional equivalences
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: florian.h...@arm.com
CC: llvm-bugs@lists.llvm.org
running `opt -newgvn -newgvn` on the code below eliminates %bf.set.1 and
%bf.clear.1, but `opt -newgvn` does not.
@a = external global i64
define void @fn1(i1 %bc) {
entry:
br label %for.cond
for.cond: ; preds = %for.cond1.1,
%entry
%tmp = phi i1 [ 1, %entry ], [ 1, %for.cond ]
%conv = zext i1 %tmp to i32
%lv = load i32, i32* bitcast (i64* @a to i32*)
%bf.clear = and i32 %lv, -131072
%bf.set = or i32 %conv, %bf.clear
%bf.clear.1 = and i32 %bf.set, -131072
%bf.set.1 = or i32 1, %bf.clear.1
br i1 %bc, label %for.cond, label %exit
exit: ; preds = %for.cond1
store i32 %bf.set.1, i32* bitcast (i64* @a to i32*)
ret void
}
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