https://llvm.org/bugs/show_bug.cgi?id=25852
Bug ID: 25852
Summary: operation on bit-fields shall yield results reduced to
bit-field size
Product: clang
Version: 3.7
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Frontend
Assignee: unassignedclangb...@nondot.org
Reporter: konstantin.vladimi...@gmail.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
Created attachment 15468
--> https://llvm.org/bugs/attachment.cgi?id=15468&action=edit
bitfield reproduction
The test (attached) is taken from gcc dejagnu and minimized. Clang 3.7 yields:
%bf.load = load i64, i64* bitcast ({ i8, i8, i8, i8, i8, [3 x i8], i8, i8,
i8, i8, i8, [3 x i8], i8, i8, i8, i8, i8, i8, [2 x i8] }* @a to i64*), align 8
%bf.clear = and i64 %bf.load, 8589934591
%mul = mul i64 %bf.clear, %bf.clear
%cmp = icmp eq i64 %mul, 0
br i1 %cmp, label %if.end, label %if.then
But after multiplication result should be casted to bitfield type, i.e. 33-bit.
Compare to GCC gimple:
<unnamed-unsigned:33> D.2209D.2209;
<unnamed-unsigned:33> D.2208D.2208;
<bb 2>:
D.2208D.2208_1 = a.u33;
D.2208D.2208_2 = a.u33;
D.2209D.2209_3 = D.2208D.2208_2 * D.2208D.2208_2;
if (D.2209D.2209_3 != 0)
goto <bb 3>;
else
goto <bb 4>;
Which is correct.
Please fix this.
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