<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Complex DWARF expressions is broken"
href="https://bugs.llvm.org/show_bug.cgi?id=33166">33166</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Complex DWARF expressions is broken
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>DebugInfo
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>amjad.aboud@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The commit r300522 (PR32382: Fix emitting complex DWARF expressions), broke the
below test:
void bar(int *test);
int foo() {
int test;
test = 1;
bar(&test);
return test;
}
foo:
0: 50 pushq %rax
1: c7 44 24 04 01 00 00 00 movl $1, 4(%rsp)
9: 48 8d 7c 24 04 leaq 4(%rsp), %rdi
e: e8 00 00 00 00 callq 0 <foo+0x13>
13: 8b 44 24 04 movl 4(%rsp), %eax
17: 59 popq %rcx
18: c3 retq
Before the commit:
------------------
define i32 @foo() local_unnamed_addr #0 !dbg !5 {
entry:
%test = alloca i32, align 4
%0 = bitcast i32* %test to i8*, !dbg !12
call void @llvm.lifetime.start(i64 4, i8* nonnull %0) #4, !dbg !12
tail call void @llvm.dbg.value(metadata i32 1, i64 0, metadata !11, metadata
!13), !dbg !12
store i32 1, i32* %test, align 4, !dbg !14, !tbaa !15
tail call void @llvm.dbg.value(metadata i32* %test, i64 0, metadata !11,
metadata !19), !dbg !12 ;; <--- This line was changed
call void @bar(i32* nonnull %test) #4, !dbg !20
%1 = load i32, i32* %test, align 4, !dbg !21, !tbaa !15
call void @llvm.dbg.value(metadata i32 %1, i64 0, metadata !11, metadata
!13), !dbg !12
call void @llvm.lifetime.end(i64 4, i8* nonnull %0) #4, !dbg !22
ret i32 %1, !dbg !21
}
!11 = !DILocalVariable(name: "test", scope: !5, file: !6, line: 3, type: !9)
!12 = !DILocation(line: 3, scope: !5)
!13 = !DIExpression()
!19 = !DIExpression(DW_OP_deref)
Contents of the .debug_loc section:
Offset Begin End Expression
00000000 0000000000000001 000000000000000e (DW_OP_consts: 1;
DW_OP_stack_value)
00000000 000000000000000e 0000000000000013 (DW_OP_breg7 (rsp): 4)
00000000 0000000000000017 0000000000000019 (DW_OP_reg0 (rax); DW_OP_piece:
4)
00000000 <End of list>
After the commit:
-----------------
define i32 @foo() local_unnamed_addr #0 !dbg !5 {
%test = alloca i32, align 4
%1 = bitcast i32* %test to i8*, !dbg !12
call void @llvm.lifetime.start.p0i8(i64 4, i8* nonnull %1) #4, !dbg !12
tail call void @llvm.dbg.value(metadata i32 1, i64 0, metadata !11, metadata
!13), !dbg !12
store i32 1, i32* %test, align 4, !dbg !14, !tbaa !15
tail call void @llvm.dbg.value(metadata i32* %test, i64 0, metadata !11,
metadata !13), !dbg !12 ;; <--- This line was changed
call void @bar(i32* nonnull %test) #4, !dbg !19
%2 = load i32, i32* %test, align 4, !dbg !20, !tbaa !15
call void @llvm.dbg.value(metadata i32 %2, i64 0, metadata !11, metadata
!13), !dbg !12
call void @llvm.lifetime.end.p0i8(i64 4, i8* nonnull %1) #4, !dbg !21
ret i32 %2, !dbg !20
}
!11 = !DILocalVariable(name: "test", scope: !5, file: !6, line: 3, type: !9)
!12 = !DILocation(line: 3, scope: !5)
!13 = !DIExpression()
Contents of the .debug_loc section:
Offset Begin End Expression
00000000 0000000000000001 000000000000000e (DW_OP_consts: 1;
DW_OP_stack_value)
00000000 000000000000000e 0000000000000013 (DW_OP_reg5 (rdi)) <-- rdi
contains address of "test".
00000000 0000000000000017 0000000000000019 (DW_OP_reg0 (rax))
00000000 <End of list>
The root cause is this change:
===================================================================
--- llvm/lib/Transforms/Utils/Local.cpp (revision 300521)
+++ llvm/lib/Transforms/Utils/Local.cpp (revision 300522)
@@ -1227,13 +1227,9 @@
// This is a call by-value or some other instruction that
// takes a pointer to the variable. Insert a *value*
// intrinsic that describes the alloca.
- SmallVector<uint64_t, 1> NewDIExpr;
- auto *DIExpr = DDI->getExpression();
- NewDIExpr.push_back(dwarf::DW_OP_deref);
- NewDIExpr.append(DIExpr->elements_begin(), DIExpr->elements_end());
DIB.insertDbgValueIntrinsic(AI, 0, DDI->getVariable(),
- DIB.createExpression(NewDIExpr),
- DDI->getDebugLoc(), CI);
+ DDI->getExpression(),
DDI->getDebugLoc(),
+ CI);
}
}
DDI->eraseFromParent();</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>