<div dir="ltr">Does this meet the bar for "if the verifier accepts it LLVM should do something sensible with it" - seems like this might not be checked by the verifier? I guess this would only happen if the IR described a whole (not fragmented) variable as being in two different parts of the stack at different portions of the function. I doubt current Clang/LLVM produce anything like that, but it's conceivable and certainly possible to artificially construct such a case, I would think?<br></div><br><div class="gmail_quote"><div dir="ltr">On Wed, Mar 22, 2017 at 10:02 AM Adrian Prantl via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: adrian<br class="gmail_msg">
Date: Wed Mar 22 11:50:16 2017<br class="gmail_msg">
New Revision: 298518<br class="gmail_msg">
<br class="gmail_msg">
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=298518&view=rev" rel="noreferrer" class="gmail_msg" target="_blank">http://llvm.org/viewvc/llvm-project?rev=298518&view=rev</a><br class="gmail_msg">
Log:<br class="gmail_msg">
Fix PR32298 by adding an early exit to getFrameIndexExprs().<br class="gmail_msg">
<br class="gmail_msg">
Also add an assertion for the case that there are multiple FI<br class="gmail_msg">
expressions with a DW_OP_LLVM_fragment; which should violate internal<br class="gmail_msg">
constraints in DbgVariable.<br class="gmail_msg">
<br class="gmail_msg">
Added:<br class="gmail_msg">
llvm/trunk/test/DebugInfo/X86/single-fi.ll<br class="gmail_msg">
Modified:<br class="gmail_msg">
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp<br class="gmail_msg">
<br class="gmail_msg">
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp<br class="gmail_msg">
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=298518&r1=298517&r2=298518&view=diff" rel="noreferrer" class="gmail_msg" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=298518&r1=298517&r2=298518&view=diff</a><br class="gmail_msg">
==============================================================================<br class="gmail_msg">
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)<br class="gmail_msg">
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Mar 22 11:50:16 2017<br class="gmail_msg">
@@ -199,6 +199,12 @@ const DIType *DbgVariable::getType() con<br class="gmail_msg">
}<br class="gmail_msg">
<br class="gmail_msg">
ArrayRef<DbgVariable::FrameIndexExpr> DbgVariable::getFrameIndexExprs() const {<br class="gmail_msg">
+ if (FrameIndexExprs.size() == 1)<br class="gmail_msg">
+ return FrameIndexExprs;<br class="gmail_msg">
+<br class="gmail_msg">
+ assert(all_of(FrameIndexExprs,<br class="gmail_msg">
+ [](const FrameIndexExpr &A) { return A.Expr->isFragment(); }) &&<br class="gmail_msg">
+ "multiple FI expressions without DW_OP_LLVM_fragment");<br class="gmail_msg">
std::sort(FrameIndexExprs.begin(), FrameIndexExprs.end(),<br class="gmail_msg">
[](const FrameIndexExpr &A, const FrameIndexExpr &B) -> bool {<br class="gmail_msg">
return A.Expr->getFragmentInfo()->OffsetInBits <<br class="gmail_msg">
<br class="gmail_msg">
Added: llvm/trunk/test/DebugInfo/X86/single-fi.ll<br class="gmail_msg">
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/single-fi.ll?rev=298518&view=auto" rel="noreferrer" class="gmail_msg" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/single-fi.ll?rev=298518&view=auto</a><br class="gmail_msg">
==============================================================================<br class="gmail_msg">
--- llvm/trunk/test/DebugInfo/X86/single-fi.ll (added)<br class="gmail_msg">
+++ llvm/trunk/test/DebugInfo/X86/single-fi.ll Wed Mar 22 11:50:16 2017<br class="gmail_msg">
@@ -0,0 +1,40 @@<br class="gmail_msg">
+; RUN: %llc_dwarf -march=x86-64 -o - %s -filetype=obj \<br class="gmail_msg">
+; RUN: | llvm-dwarfdump -debug-dump=info - | FileCheck %s<br class="gmail_msg">
+; A single FI location. This used to trigger an assertion in debug libstdc++.<br class="gmail_msg">
+; CHECK: DW_TAG_formal_parameter<br class="gmail_msg">
+; fbreg -8<br class="gmail_msg">
+; CHECK-NEXT: DW_AT_location {{.*}} (<0x2> 91 78 )<br class="gmail_msg">
+; CHECK-NEXT: DW_AT_name {{.*}} "dipsy"<br class="gmail_msg">
+define void @tinkywinky(i8* %dipsy) !dbg !6 {<br class="gmail_msg">
+entry:<br class="gmail_msg">
+ %dipsy.addr = alloca i8*<br class="gmail_msg">
+ store i8* %dipsy, i8** %dipsy.addr<br class="gmail_msg">
+ call void @llvm.dbg.declare(metadata i8** %dipsy.addr, metadata !12, metadata<br class="gmail_msg">
+!13), !dbg !14<br class="gmail_msg">
+ ret void, !dbg !15<br class="gmail_msg">
+}<br class="gmail_msg">
+<br class="gmail_msg">
+declare void @llvm.dbg.declare(metadata, metadata, metadata)<br class="gmail_msg">
+<br class="gmail_msg">
+!<a href="http://llvm.dbg.cu" rel="noreferrer" class="gmail_msg" target="_blank">llvm.dbg.cu</a> = !{!0}<br class="gmail_msg">
+!llvm.module.flags = !{!3, !4}<br class="gmail_msg">
+!llvm.ident = !{!5}<br class="gmail_msg">
+<br class="gmail_msg">
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 5.0.0 (trunk 297917) (llvm/trunk 297929)", isOptimized: false,<br class="gmail_msg">
+runtimeVersion: 0, emissionKind: FullDebug, enums: !2)<br class="gmail_msg">
+!1 = !DIFile(filename: "teletubbies.c", directory: "/home/davide/work/llvm/build-clang/bin")<br class="gmail_msg">
+!2 = !{}<br class="gmail_msg">
+!3 = !{i32 2, !"Dwarf Version", i32 4}<br class="gmail_msg">
+!4 = !{i32 2, !"Debug Info Version", i32 3}<br class="gmail_msg">
+!5 = !{!"clang version 5.0.0 (trunk 297917) (llvm/trunk 297929)"}<br class="gmail_msg">
+!6 = distinct !DISubprogram(name: "tinkywinky", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags:<br class="gmail_msg">
+DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)<br class="gmail_msg">
+!7 = !DISubroutineType(types: !8)<br class="gmail_msg">
+!8 = !{null, !9}<br class="gmail_msg">
+!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)<br class="gmail_msg">
+!10 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !11)<br class="gmail_msg">
+!11 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)<br class="gmail_msg">
+!12 = !DILocalVariable(name: "dipsy", arg: 1, scope: !6, file: !1, line: 1, type: !9)<br class="gmail_msg">
+!13 = !DIExpression()<br class="gmail_msg">
+!14 = !DILocation(line: 1, column: 29, scope: !6)<br class="gmail_msg">
+!15 = !DILocation(line: 1, column: 37, scope: !6)<br class="gmail_msg">
<br class="gmail_msg">
<br class="gmail_msg">
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</blockquote></div>