https://llvm.org/bugs/show_bug.cgi?id=28562
Bug ID: 28562
Summary: GVN ignores inbounds of getelementptr
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: kyoo...@gmail.com
CC: david.majne...@gmail.com, dber...@dberlin.org,
listm...@philipreames.com, llvm-bugs@lists.llvm.org,
nunoplo...@sapo.pt, san...@playingwithpointers.com
Classification: Unclassified
GVN ignores the inbounds keyword of getelementptr instructions.
As a consequence, it may replace a GEP instruction without inbounds with
another GEP with inbounds.
Running 'opt -gvn' for the source code below produces the following result:
source:
define i32* @foo(i32* %a) {
%x1 = getelementptr inbounds i32, i32* %a, i32 10
%x2 = getelementptr i32, i32* %a, i32 10
ret i32* %x2
}
result:
define i32* @foo(i32* %a) {
%x1 = getelementptr inbounds i32, i32* %a, i32 10
ret i32* %x1
}
I think foo's behavior is changed, since the GEP with inbounds can be a poison
value.
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