http://llvm.org/bugs/show_bug.cgi?id=15501
Bug ID: 15501
Summary: LCSSA and SSAUpdater incorrectly update dbg.value
Product: new-bugs
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 10170
--> http://llvm.org/bugs/attachment.cgi?id=10170&action=edit
Contrived test case
clang -g -c -emit-llvm -S loop.c -O3 -mllvm -disable-llvm-optzns -o loop.ll
opt loop.ll -O3 -S -o loop-O3.ll
Notice that the dbg.value inside the loop now refers to the LCSSA value outside
the loop.
if.end2: ; preds = %if.end
%call3 = tail call i32 (...)* @bar() #2, !dbg !21
%dec = add nsw i32 %dec5, -1, !dbg !17
tail call void @llvm.dbg.value(metadata !{i32 %dec.lcssa}, i64 0, metadata
!12), !dbg !17
%cmp = icmp slt i32 %dec, 0, !dbg !19
br i1 %cmp, label %while.end, label %if.end, !dbg !19
while.end: ; preds = %if.end2, %if.end,
%entry
%dec.lcssa = phi i32 [ %dec3, %entry ], [ %dec5, %if.end ], [ %dec, %if.end2
]
llc does yield an assert, but it isn't very helpful.
Assertion failed: (TheCU && "Unable to find compile unit!"), function
beginFunction, file /Volumes/Source/fix/lib/CodeGen/AsmPrinter/DwarfDebug.cpp,
line 1362.
This is a general problem with RAUW on ValueHandle. It would be easy to fix
this test case without fixing the general problem. RAUW should *not* be called
by LCSSA or SSAUpdater.
See PR15413.
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