uabelho added a comment.
Hi,
I'm seeing what I think is a miscompile with this:
opt -S -dse -o - dse.ll
on
@x = global [10 x [10 x i16]] zeroinitializer, align 1
define i16 @f() {
entry:
br label %do.body
do.body: ; preds = %if.end, %entry
%i.0 = phi i16 [ 0, %entry ], [ %inc, %if.end ]
%j.0 = phi i16 [ 0, %entry ], [ %add, %if.end ]
%arrayidx2 = getelementptr inbounds [10 x [10 x i16]], [10 x [10 x i16]]*
@x, i16 0, i16 %i.0, i16 %j.0
store i16 2, i16* %arrayidx2, align 1
%exitcond = icmp eq i16 %i.0, 4
br i1 %exitcond, label %if.end10, label %if.end
if.end: ; preds = %do.body
%inc = add nuw nsw i16 %i.0, 1
%add = add nuw nsw i16 %j.0, 2
br label %do.body
if.end10: ; preds = %do.body
store i16 1, i16* %arrayidx2, align 1
ret i16 0
}
gives
x = global [10 x [10 x i16]] zeroinitializer, align 1
define i16 @f() {
entry:
br label %do.body
do.body: ; preds = %if.end, %entry
%i.0 = phi i16 [ 0, %entry ], [ %inc, %if.end ]
%j.0 = phi i16 [ 0, %entry ], [ %add, %if.end ]
%arrayidx2 = getelementptr inbounds [10 x [10 x i16]], [10 x [10 x i16]]*
@x, i16 0, i16 %i.0, i16 %j.0
%exitcond = icmp eq i16 %i.0, 4
br i1 %exitcond, label %if.end10, label %if.end
if.end: ; preds = %do.body
%inc = add nuw nsw i16 %i.0, 1
%add = add nuw nsw i16 %j.0, 2
br label %do.body
if.end10: ; preds = %do.body
store i16 1, i16* %arrayidx2, align 1
ret i16 0
}
So the store in the loop has been removed, which I think is incorrect.
The
store i16 2
in the loop should be carried out at (i,j) == (0,0), (1,2), (2,4), (3,6) och
(4,8) and then the last of them should be overwritten by the
store i16 1
after the loop, but now the store in the loop is removed so we're only left
with a written 1 at (4,8).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87163/new/
https://reviews.llvm.org/D87163
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
