[llvm] r288212 - Emit 'no line' information for interesting 'orphan' instructions.
Paul Robinson via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 29 14:41:17 PST 2016
Author: probinson
Date: Tue Nov 29 16:41:16 2016
New Revision: 288212
URL: http://llvm.org/viewvc/llvm-project?rev=288212&view=rev
Log:
Emit 'no line' information for interesting 'orphan' instructions.
DWARF specifies that "line 0" really means "no appropriate source
location" in the line table. Use this for branch targets and some
other cases that have no specified source location, to prevent
inheriting unfortunate line numbers from physically preceding
instructions (which might be from completely unrelated source).
Differential Revision: http://reviews.llvm.org/D24180
Added:
llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
llvm/trunk/test/CodeGen/X86/stack-protector.ll
llvm/trunk/test/DebugInfo/AArch64/line-header.ll
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp?rev=288212&r1=288211&r2=288212&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp Tue Nov 29 16:41:16 2016
@@ -201,8 +201,10 @@ void DebugHandlerBase::endInstruction()
assert(CurMI != nullptr);
// Don't create a new label after DBG_VALUE instructions.
// They don't generate code.
- if (!CurMI->isDebugValue())
+ if (!CurMI->isDebugValue()) {
PrevLabel = nullptr;
+ PrevInstBB = CurMI->getParent();
+ }
DenseMap<const MachineInstr *, MCSymbol *>::iterator I =
LabelsAfterInsn.find(CurMI);
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h?rev=288212&r1=288211&r2=288212&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h Tue Nov 29 16:41:16 2016
@@ -38,10 +38,12 @@ protected:
MachineModuleInfo *MMI;
/// Previous instruction's location information. This is used to
- /// determine label location to indicate scope boundries in dwarf
- /// debug info.
+ /// determine label location to indicate scope boundaries in debug info.
+ /// We track the previous instruction's source location (if not line 0),
+ /// whether it was a label, and its parent BB.
DebugLoc PrevInstLoc;
MCSymbol *PrevLabel = nullptr;
+ const MachineBasicBlock *PrevInstBB = nullptr;
/// This location indicates end of function prologue and beginning of
/// function body.
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=288212&r1=288211&r2=288212&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Tue Nov 29 16:41:16 2016
@@ -1010,31 +1010,70 @@ void DwarfDebug::beginInstruction(const
if (MI->isDebugValue())
return;
const DebugLoc &DL = MI->getDebugLoc();
- if (DL == PrevInstLoc)
+ // When we emit a line-0 record, we don't update PrevInstLoc; so look at
+ // the last line number actually emitted, to see if it was line 0.
+ unsigned LastAsmLine =
+ Asm->OutStreamer->getContext().getCurrentDwarfLoc().getLine();
+
+ if (DL == PrevInstLoc) {
+ // If we have an ongoing unspecified location, nothing to do here.
+ if (!DL)
+ return;
+ // We have an explicit location, same as the previous location.
+ // But we might be coming back to it after a line 0 record.
+ if (LastAsmLine == 0 && DL.getLine() != 0) {
+ // Reinstate the source location but not marked as a statement.
+ const MDNode *Scope = DL.getScope();
+ recordSourceLine(DL.getLine(), DL.getCol(), Scope, /*Flags=*/0);
+ }
return;
+ }
if (!DL) {
// We have an unspecified location, which might want to be line 0.
- if (UnknownLocations) {
- PrevInstLoc = DL;
- recordSourceLine(0, 0, nullptr, 0);
+ // If we have already emitted a line-0 record, don't repeat it.
+ if (LastAsmLine == 0)
+ return;
+ // See if we have a reason to emit a line-0 record now.
+ // Reasons to emit a line-0 record include:
+ // - User asked for it (UnknownLocations).
+ // - Instruction has a label, so it's referenced from somewhere else,
+ // possibly debug information; we want it to have a source location.
+ // - Instruction is at the top of a block; we don't want to inherit the
+ // location from the physically previous (maybe unrelated) block.
+ if (UnknownLocations || PrevLabel ||
+ (PrevInstBB && PrevInstBB != MI->getParent())) {
+ // Preserve the file number, if we can, to save space in the line table.
+ // Do not update PrevInstLoc, it remembers the last non-0 line.
+ // FIXME: Also preserve the column number, to save more space?
+ const MDNode *Scope = PrevInstLoc ? PrevInstLoc.getScope() : nullptr;
+ recordSourceLine(0, 0, Scope, 0);
}
return;
}
- // We have a new, explicit location.
+ // We have an explicit location, different from the previous location.
+ // Don't repeat a line-0 record, but otherwise emit the new location.
+ // (The new location might be an explicit line 0, which we do emit.)
+ if (DL.getLine() == 0 && LastAsmLine == 0)
+ return;
unsigned Flags = 0;
- PrevInstLoc = DL;
if (DL == PrologEndLoc) {
Flags |= DWARF2_FLAG_PROLOGUE_END | DWARF2_FLAG_IS_STMT;
PrologEndLoc = DebugLoc();
}
- if (DL.getLine() !=
- Asm->OutStreamer->getContext().getCurrentDwarfLoc().getLine())
+ // If the line changed, we call that a new statement; unless we went to
+ // line 0 and came back, in which case it is not a new statement.
+ unsigned OldLine = PrevInstLoc ? PrevInstLoc.getLine() : LastAsmLine;
+ if (DL.getLine() && DL.getLine() != OldLine)
Flags |= DWARF2_FLAG_IS_STMT;
const MDNode *Scope = DL.getScope();
recordSourceLine(DL.getLine(), DL.getCol(), Scope, Flags);
+
+ // If we're not at line 0, remember this location.
+ if (DL.getLine())
+ PrevInstLoc = DL;
}
static DebugLoc findPrologueEndLoc(const MachineFunction *MF) {
Modified: llvm/trunk/test/CodeGen/X86/stack-protector.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/stack-protector.ll?rev=288212&r1=288211&r2=288212&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/stack-protector.ll (original)
+++ llvm/trunk/test/CodeGen/X86/stack-protector.ll Tue Nov 29 16:41:16 2016
@@ -3888,23 +3888,27 @@ entry:
define void @test32() #1 !dbg !7 {
entry:
; LINUX-I386-LABEL: test32:
-; LINUX-I386: .loc 1 0 0 prologue_end
+; LINUX-I386: .loc 1 4 2 prologue_end
+; LINUX-I386: .loc 1 0 0
; LINUX-I386-NEXT: calll __stack_chk_fail
; LINUX-X64-LABEL: test32:
-; LINUX-X64: .loc 1 0 0 prologue_end
+; LINUX-X64: .loc 1 4 2 prologue_end
+; LINUX-X64: .loc 1 0 0
; LINUX-X64-NEXT: callq __stack_chk_fail
; LINUX-KERNEL-X64-LABEL: test32:
-; LINUX-KERNEL-X64: .loc 1 0 0 prologue_end
+; LINUX-KERNEL-X64: .loc 1 4 2 prologue_end
+; LINUX-KERNEL-X64: .loc 1 0 0
; LINUX-KERNEL-X64-NEXT: callq __stack_chk_fail
; OPENBSD-AMD64-LABEL: test32:
-; OPENBSD-AMD64: .loc 1 0 0 prologue_end
+; OPENBSD-AMD64: .loc 1 4 2 prologue_end
+; OPENBSD-AMD64: .loc 1 0 0
; OPENBSD-AMD64-NEXT: movl
; OPENBSD-AMD64-NEXT: callq __stack_smash_handler
%0 = alloca [5 x i8], align 1
- ret void
+ ret void, !dbg !9
}
declare double @testi_aux()
@@ -3940,3 +3944,4 @@ attributes #5 = { ssp "stack-protector-b
!6 = distinct !DISubprogram(name: "__stack_chk_fail", scope: !1, type: !8, unit: !0)
!7 = distinct !DISubprogram(name: "test32", scope: !1, type: !8, unit: !0)
!8 = !DISubroutineType(types: !2)
+!9 = !DILocation(line: 4, column: 2, scope: !7)
Modified: llvm/trunk/test/DebugInfo/AArch64/line-header.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/AArch64/line-header.ll?rev=288212&r1=288211&r2=288212&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/AArch64/line-header.ll (original)
+++ llvm/trunk/test/DebugInfo/AArch64/line-header.ll Tue Nov 29 16:41:16 2016
@@ -3,4 +3,4 @@
; check line table length is correctly calculated for both big and little endian
CHECK-LABEL: .debug_line contents:
-CHECK: total_length: 0x0000003c
+CHECK: total_length: 0x0000003e
Added: llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll?rev=288212&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll (added)
+++ llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll Tue Nov 29 16:41:16 2016
@@ -0,0 +1,74 @@
+; Verify "no source location" directives appear in appropriate places.
+; RUN: llc %s -o - | FileCheck %s
+
+; Generated from this .cpp targeting linux using -g
+; and then removed function attributes as clutter.
+;
+; void bar(int *);
+; void baz(int *);
+; # 5 "no-source-loc.cpp"
+; void foo(int x) {
+; int z;
+; if (x)
+; # 20 "include.h"
+; bar(&z);
+; # 10 "no-source-loc.cpp"
+; baz(&z);
+; }
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: uwtable
+define void @_Z3fooi(i32 %x) !dbg !6 {
+entry:
+ %x.addr = alloca i32, align 4
+ %z = alloca i32, align 4
+ store i32 %x, i32* %x.addr, align 4
+ %0 = load i32, i32* %x.addr, align 4, !dbg !8
+ %tobool = icmp ne i32 %0, 0, !dbg !8
+ br i1 %tobool, label %if.then, label %if.end, !dbg !8
+
+if.then: ; preds = %entry
+ call void @_Z3barPi(i32* %z), !dbg !9
+ br label %if.end, !dbg !9
+
+if.end: ; preds = %if.then, %entry
+ call void @_Z3bazPi(i32* %z), !dbg !12
+ ret void, !dbg !14
+}
+
+; CHECK: .loc 1 7 7
+; CHECK-NOT: .loc
+; CHECK: .loc 1 0 0 is_stmt 0
+; CHECK-NOT: .loc
+; CHECK: .loc 2 20 5 is_stmt 1
+; CHECK: .LBB0_2:
+; CHECK-NEXT: .loc 2 0 0 is_stmt 0
+; CHECK-NOT: .loc
+; CHECK: .loc 1 10 3 is_stmt 1
+
+
+declare void @_Z3barPi(i32*)
+
+declare void @_Z3bazPi(i32*)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0 (trunk 278782)", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2)
+!1 = !DIFile(filename: "no-source-loc.cpp", directory: "/tests")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 4.0.0 (trunk 278782)"}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 7, column: 7, scope: !6)
+!9 = !DILocation(line: 20, column: 5, scope: !10)
+!10 = !DILexicalBlockFile(scope: !6, file: !11, discriminator: 0)
+!11 = !DIFile(filename: "include.h", directory: "/tests")
+!12 = !DILocation(line: 10, column: 3, scope: !13)
+!13 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 0)
+!14 = !DILocation(line: 11, column: 1, scope: !13)
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