[llvm] r311951 - Fix a logic error in DwarfExpression::addMachineReg()

[Adrian Prantl via llvm-commits]

Author: adrian
Date: Mon Aug 28 16:07:43 2017
New Revision: 311951

URL: http://llvm.org/viewvc/llvm-project?rev=311951&view=rev
Log:
Fix a logic error in DwarfExpression::addMachineReg()

This fixes PR34323 and thus splitting undescribable registers into
smaller, describable sub-registers.

https://bugs.llvm.org/show_bug.cgi?id=34323

Added:
    llvm/trunk/test/DebugInfo/Sparc/subreg.ll
Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp?rev=311951&r1=311950&r2=311951&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfExpression.cpp Mon Aug 28 16:07:43 2017
@@ -133,13 +133,12 @@ bool DwarfExpression::addMachineReg(cons
 
     // Intersection between the bits we already emitted and the bits
     // covered by this subregister.
-    SmallBitVector Intersection(RegSize, false);
-    Intersection.set(Offset, Offset + Size);
-    Intersection ^= Coverage;
+    SmallBitVector CurSubReg(RegSize, false);
+    CurSubReg.set(Offset, Offset + Size);
 
     // If this sub-register has a DWARF number and we haven't covered
     // its range, emit a DWARF piece for it.
-    if (Reg >= 0 && Intersection.any()) {
+    if (Reg >= 0 && CurSubReg.test(Coverage)) {
       // Emit a piece for any gap in the coverage.
       if (Offset > CurPos)
         DwarfRegs.push_back({-1, Offset - CurPos, nullptr});

Added: llvm/trunk/test/DebugInfo/Sparc/subreg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/Sparc/subreg.ll?rev=311951&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/Sparc/subreg.ll (added)
+++ llvm/trunk/test/DebugInfo/Sparc/subreg.ll Mon Aug 28 16:07:43 2017
@@ -0,0 +1,60 @@
+; RUN: llc -filetype=obj -O0 < %s -mtriple sparc64-unknown-linux-gnu | llvm-dwarfdump - | FileCheck %s
+; The undescribable 128-bit register should be split into two 64-bit registers.
+; CHECK: Location description: 90 4a 93 08 90 4b 93 08
+;                              DW_OP_reg74 DW_OP_piece 8 DW_OP_reg75 DW_OP_piece 8 ...
+source_filename = "/tmp/t.c"
+target datalayout = "E-m:e-i64:64-n32:64-S128"
+target triple = "sparc64"
+
+ at a = common local_unnamed_addr global fp128 0xL00000000000000000000000000000000, align 16, !dbg !0
+
+; Function Attrs: nounwind
+define signext i32 @fn1() local_unnamed_addr #0 !dbg !11 {
+entry:
+  tail call void @llvm.dbg.declare(metadata { fp128, fp128 }* undef, metadata !16, metadata !DIExpression()), !dbg !18
+  store fp128 fmul (fp128 undef, fp128 0xL00000000000000003FFF000000000000), fp128* @a, align 16, !dbg !19, !tbaa !20
+  tail call void @llvm.dbg.value(metadata fp128 fmul (fp128 undef, fp128 0xL00000000000000003FFF000000000000), metadata !16, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 128)), !dbg !18
+  tail call void @llvm.dbg.value(metadata fp128 0xL00000000000000000000000000000000, metadata !16, metadata !DIExpression(DW_OP_LLVM_fragment, 128, 128)), !dbg !18
+  ret i32 undef, !dbg !24
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind
+declare void @llvm.stackprotector(i8*, i8**) #2
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone speculatable }
+attributes #2 = { nounwind }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9}
+
+!0 = !DIGlobalVariableExpression(var: !1)
+!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 6.0.0 (trunk 311908) (llvm/trunk 311915)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "t.c", directory: "/")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "long double", size: 128, encoding: DW_ATE_float)
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!11 = distinct !DISubprogram(name: "fn1", scope: !3, file: !3, line: 1, type: !12, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: true, unit: !2, variables: !15)
+!12 = !DISubroutineType(types: !13)
+!13 = !{!14}
+!14 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!15 = !{!16}
+!16 = !DILocalVariable(name: "b", scope: !11, file: !3, line: 1, type: !17)
+!17 = !DIBasicType(name: "complex", size: 256, encoding: DW_ATE_complex_float)
+!18 = !DILocation(line: 1, column: 45, scope: !11)
+!19 = !DILocation(line: 1, column: 51, scope: !11)
+!20 = !{!21, !21, i64 0}
+!21 = !{!"long double", !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 1, column: 63, scope: !11)