http://llvm.org/bugs/show_bug.cgi?id=3198
Summary: GVN not eliminating fully redundant GEPs
Product: libraries
Version: 1.0
Platform: PC
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: Scalar Optimizations
AssignedTo: [EMAIL PROTECTED]
ReportedBy: [EMAIL PROTECTED]
CC: [EMAIL PROTECTED], [email protected]
In the testcase test/Transforms/GVN/rle-must-alias.ll, if you disable load
elimination, you'll see that GVN produces:
bb: ; preds = %entry
%2 = tail call i32 (...)* @bar() nounwind ; <i32>
[#uses=0]
%3 = getelementptr [100 x i32]* @H, i32 0, i32 %i ;
<i32*> [#uses=1]
%4 = load i32* %3, align 4 ; <i32> [#uses=1]
store i32 %4, i32* @G, align 4
br label %bb3
bb1: ; preds = %entry
%5 = tail call i32 (...)* @baz() nounwind ; <i32>
[#uses=0]
%6 = getelementptr [100 x i32]* @H, i32 0, i32 %i ;
<i32*> [#uses=1]
%7 = load i32* %6, align 4 ; <i32> [#uses=2]
store i32 %7, i32* @G, align 4
%8 = icmp eq i32 %7, 0 ; <i1> [#uses=1]
br i1 %8, label %bb3, label %bb4
bb3: ; preds = %bb1, %bb
%9 = getelementptr [100 x i32]* @H, i32 0, i32 %i ;
<i32*> [#uses=1]
The %9 load is fully redundant with %3/%6. I thought that GVN could handle
this case already?
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