[llvm] r262247 - Fix PR26585 by improving the promotion of DBG_VALUEs to DW_AT_locations.
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 10 08:23:28 PST 2016
> On Mar 9, 2016, at 5:25 PM, Pieb, Wolfgang <Wolfgang_Pieb at playstation.sony.com> wrote:
>
> Hi, I noticed that with the following source:
>
> /*========================*/
> extern void use(void *, int *);
>
> void foo(void *ptr) {
> int arr[100] = {1};
> use(ptr, arr);
> }
> /*========================*/
>
> native linux, clang -O2 -march=btver2 -g -c foo.c
>
> After the patch the location for 'ptr' becomes a single-entry location list rather than a DW_AT_location. Should validAtEntry() in DwarfDebug.cpp skip CFI instructions perhaps? I can file a PR if you like.
That sounds reasonable; please do!
-- adrian
>
> -- wolfgang
>
>> -----Original Message-----
>> From: llvm-commits [mailto:llvm-commits-bounces at lists.llvm.org] On
>> Behalf Of Adrian Prantl via llvm-commits
>> Sent: Monday, February 29, 2016 11:50 AM
>> To: llvm-commits at lists.llvm.org
>> Subject: [llvm] r262247 - Fix PR26585 by improving the promotion of
>> DBG_VALUEs to DW_AT_locations.
>>
>> Author: adrian
>> Date: Mon Feb 29 13:49:46 2016
>> New Revision: 262247
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=262247&view=rev
>> Log:
>> Fix PR26585 by improving the promotion of DBG_VALUEs to
>> DW_AT_locations.
>> When a variable is described by a single DBG_VALUE instruction we can
>> often use a more efficient inline DW_AT_location instead of using a
>> location list.
>>
>> This commit makes the heuristic that decides when to apply this
>> optimization stricter by also verifying that the DBG_VALUE is live at
>> the entry of the function (instead of just checking that it is valid
>> until the end of the function).
>>
>> <rdar://problem/24611008>
>>
>> Added:
>> llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll
>> Modified:
>> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>> llvm/trunk/test/DebugInfo/X86/PR26148.ll
>> llvm/trunk/test/DebugInfo/X86/parameters.ll
>> llvm/trunk/test/DebugInfo/X86/pieces-2.ll
>> llvm/trunk/test/DebugInfo/X86/pieces-3.ll
>> llvm/trunk/test/DebugInfo/X86/reference-argument.ll
>> llvm/trunk/test/DebugInfo/X86/subregisters.ll
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=262247&r1=
>> 262246&r2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Mon Feb 29
>> 13:49:46
>> +++ 2016
>> @@ -935,6 +935,18 @@ DbgVariable *DwarfDebug::createConcreteV
>> return ConcreteVariables.back().get(); }
>>
>> +// Determine whether this DBG_VALUE is valid at the beginning of the
>> function.
>> +static bool validAtEntry(const MachineInstr *MInsn) {
>> + auto MBB = MInsn->getParent();
>> + // Is it in the entry basic block?
>> + if (!MBB->pred_empty())
>> + return false;
>> + for (MachineBasicBlock::const_reverse_iterator I(MInsn); I != MBB-
>>> rend(); ++I)
>> + if (!(I->isDebugValue() || I->getFlag(MachineInstr::FrameSetup)))
>> + return false;
>> + return true;
>> +}
>> +
>> // Find variables for each lexical scope.
>> void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
>> const DISubprogram *SP, @@ -967,8
>> +979,11 @@ void DwarfDebug::collectVariableInfo(Dwa
>> const MachineInstr *MInsn = Ranges.front().first;
>> assert(MInsn->isDebugValue() && "History must begin with debug
>> value");
>>
>> - // Check if the first DBG_VALUE is valid for the rest of the
>> function.
>> - if (Ranges.size() == 1 && Ranges.front().second == nullptr) {
>> + // Check if there is a single DBG_VALUE, valid throughout the
>> function.
>> + // A single constant is also considered valid for the entire
>> function.
>> + if (Ranges.size() == 1 &&
>> + (MInsn->getOperand(0).isImm() ||
>> + (validAtEntry(MInsn) && Ranges.front().second == nullptr))) {
>> RegVar->initializeDbgValue(MInsn);
>> continue;
>> }
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/PR26148.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/PR26148.ll?rev=262247&r1=262246&r
>> 2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/PR26148.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/PR26148.ll Mon Feb 29 13:49:46 2016
>> @@ -19,7 +19,7 @@
>> ; AS in 26163, we expect two ranges (as opposed to one), the first one
>> being zero sized ; ; -; CHECK: 0x00000000: Beginning address offset:
>> 0x0000000000000004
>> +; CHECK: 0x00000025: Beginning address offset: 0x0000000000000004
>> ; CHECK: Ending address offset: 0x0000000000000004
>> ; CHECK: Location description: 10 03 55 93 04
>> ; CHECK: Beginning address offset: 0x0000000000000004
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/parameters.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/parameters.ll?rev=262247&r1=26224
>> 6&r2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/parameters.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/parameters.ll Mon Feb 29 13:49:46
>> 2016
>> @@ -25,15 +25,19 @@
>> ; CHECK: debug_info contents
>> ; 0x74 is DW_OP_breg4, showing that the parameter is accessed
>> indirectly ; (with a zero offset) from the register parameter -;
>> CHECK: DW_AT_location{{.*}}(<0x0{{.}}> 74 00
>> +; CHECK: DW_AT_location [DW_FORM_data4] ([[F_LOC:0x[0-9]*]])
>> ; CHECK-NOT: DW_TAG
>> ; CHECK: DW_AT_name{{.*}} = "f"
>> -
>> +;
>> ; CHECK: DW_AT_location{{.*}}([[G_LOC:0x[0-9]*]])
>> ; CHECK-NOT: DW_TAG
>> ; CHECK: DW_AT_name{{.*}} = "g"
>> +;
>> ; CHECK: debug_loc contents
>> -; CHECK-NEXT: [[G_LOC]]: Beginning
>> +; CHECK: [[F_LOC]]: Beginning
>> +; CHECK-NEXT: Ending
>> +; CHECK-NEXT: Location description: 74 00
>> +; CHECK: [[G_LOC]]: Beginning
>> ; CHECK-NEXT: Ending
>> ; CHECK-NEXT: Location description: 74 00
>>
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/pieces-2.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/pieces-
>> 2.ll?rev=262247&r1=262246&r2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/pieces-2.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/pieces-2.ll Mon Feb 29 13:49:46 2016
>> @@ -17,10 +17,15 @@
>> ;
>> ;
>> ; CHECK: DW_TAG_variable [4]
>> -; rax, piece
>> 0x00000004
>> -; CHECK-NEXT: DW_AT_location [DW_FORM_block1]{{.*}}50 93 04
>> +; CHECK-NEXT: DW_AT_location [DW_FORM_data4] ([[LOC:.*]])
>> ; CHECK-NEXT: DW_AT_name {{.*}}"i1"
>> ;
>> +; CHECK: .debug_loc
>> +; CHECK: [[LOC]]: Beginning address offset: 0x0000000000000004
>> +; CHECK-NEXT: Ending address offset: 0x0000000000000005
>> +; rax, piece 0x00000004
>> +; CHECK-NEXT: Location description: 50 93 04
>> +;
>> ; ModuleID = '/Volumes/Data/llvm/test/DebugInfo/X86/sroasplit-1.ll'
>> target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
>> target triple = "x86_64-apple-macosx10.9.0"
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/pieces-3.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/pieces-
>> 3.ll?rev=262247&r1=262246&r2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/pieces-3.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/pieces-3.ll Mon Feb 29 13:49:46 2016
>> @@ -16,19 +16,22 @@
>> ; }
>> ;
>> ; CHECK: DW_TAG_formal_parameter [3]
>> -; CHECK-NEXT: DW_AT_location [DW_FORM_data4] ([[LOC:.*]])
>> +; CHECK-NEXT: DW_AT_location [DW_FORM_data4] ([[LOC1:.*]])
>> ; CHECK-NEXT: DW_AT_name {{.*}}"outer"
>> ; CHECK: DW_TAG_variable
>> -; rsi, piece
>> 0x00000004
>> -; CHECK-NEXT: DW_AT_location [DW_FORM_block1] {{.*}} 54 93 04
>> +; CHECK-NEXT: DW_AT_location [DW_FORM_data4] ([[LOC2:.*]])
>> ; CHECK-NEXT: "i1"
>> ;
>> ; CHECK: .debug_loc
>> -; CHECK: [[LOC]]:
>> -; CHECK: Beginning address offset: 0x0000000000000000
>> -; CHECK: Ending address offset: 0x0000000000000008
>> -; rdi, piece 0x00000008, piece 0x00000004, rsi, piece 0x00000004 -;
>> CHECK: Location description: 55 93 08 93 04 54 93 04
>> +; CHECK: [[LOC1]]: Beginning address offset: 0x0000000000000000
>> +; CHECK: Ending address offset: 0x0000000000000008
>> +; rdi, piece 0x00000008, piece 0x00000004, rsi, piece
>> 0x00000004
>> +; CHECK-NEXT: Location description: 55 93 08 93 04 54 93 04 ; CHECK:
>> +[[LOC2]]: Beginning address offset: 0x0000000000000004
>> +; CHECK-NEXT: Ending address offset: 0x0000000000000008
>> +; rsi, piece 0x00000004
>> +; CHECK-NEXT: Location description: 54 93 04
>> +
>> ;
>> ; ModuleID = '/Volumes/Data/llvm/test/DebugInfo/X86/sroasplit-2.ll'
>> target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/reference-argument.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/reference-
>> argument.ll?rev=262247&r1=262246&r2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/reference-argument.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/reference-argument.ll Mon Feb 29
>> +++ 13:49:46 2016
>> @@ -1,8 +1,9 @@
>> -; RUN: llc -mtriple=x86_64-apple-macosx10.9.0 -filetype=obj -O0 < %s |
>> llvm-dwarfdump -debug-dump=info - | FileCheck %s
>> +; RUN: llc -mtriple=x86_64-apple-macosx10.9.0 -filetype=obj -O0 < %s |
>> +llvm-dwarfdump -debug-dump=all - | FileCheck %s
>> ; ModuleID = 'aggregate-indirect-arg.cpp'
>> ; extracted from debuginfo-tests/aggregate-indirect-arg.cpp
>>
>> ; v should be a pointer.
>> +; CHECK: .debug_info contents:
>> ; CHECK: DW_TAG_subprogram
>> ; CHECK: DW_AT_specification {{.*}} "_ZN1A3fooE4SVal"
>> ; CHECK-NOT: DW_TAG_subprogram
>> @@ -10,9 +11,11 @@
>> ; CHECK: DW_AT_name {{.*}} "this"
>> ; CHECK-NOT: DW_TAG_subprogram
>> ; CHECK: DW_TAG_formal_parameter
>> -; rsi+0
>> -; CHECK-NEXT: DW_AT_location [DW_FORM_block1] (<0x02> 74 00{{
>> *}})
>> +; CHECK-NEXT: DW_AT_location [DW_FORM_data4] (0x00000000)
>> ; CHECK-NEXT: DW_AT_name {{.*}} "v"
>> +; CHECK: .debug_loc contents:
>> +; rsi+0
>> +; CHECK: Location description: 74 00
>>
>> target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-
>> i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-
>> f80:128:128-n8:16:32:64-S128"
>> target triple = "x86_64-apple-macosx10.9.0"
>>
>> Added: llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/single-
>> dbg_value.ll?rev=262247&view=auto
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll (added)
>> +++ llvm/trunk/test/DebugInfo/X86/single-dbg_value.ll Mon Feb 29
>> +++ 13:49:46 2016
>> @@ -0,0 +1,71 @@
>> +; RUN: %llc_dwarf -stop-after=livedebugvalues -o /dev/null %s 2>&1 \
>> +; RUN: | FileCheck %s --check-prefix=SANITY
>> +; RUN: %llc_dwarf -march=x86-64 -o - %s -filetype=obj \
>> +; RUN: | llvm-dwarfdump -debug-dump=all - | FileCheck %s
>> +;
>> +; CHECK: .debug_info contents:
>> +; CHECK: DW_TAG_variable
>> +; CHECK-NEXT: DW_AT_location [DW_FORM_data4]
>> +; CHECK-NEXT: DW_AT_name{{.*}}"a"
>> +; CHECK: .debug_loc contents:
>> +; rax, piece 0x00000004
>> +; CHECK: Location description: 50 93 04 ; SANITY: DBG_VALUE ;
>> +SANITY-NOT: DBG_VALUE ; ModuleID = 'test.ll'
>> +; Compiled with -O:
>> +; void h(int);
>> +; int g();
>> +; void f() {
>> +; h(0);
>> +; int a = g();
>> +; h(a);
>> +; }
>> +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
>> +target triple = "x86_64-apple-macosx"
>> +
>> +; Function Attrs: nounwind ssp uwtable
>> +define void @f() #0 !dbg !4 {
>> +entry:
>> + tail call void @h(i32 0) #2, !dbg !14
>> + %call = tail call i32 (...) @g() #2, !dbg !15
>> + tail call void @llvm.dbg.value(metadata i32 %call, i64 0, metadata
>> +!8, metadata !16), !dbg !17
>> + tail call void @h(i32 %call) #2, !dbg !18
>> + ret void, !dbg !19
>> +}
>> +
>> +declare void @h(i32)
>> +
>> +declare i32 @g(...)
>> +
>> +; Function Attrs: nounwind readnone
>> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
>> +
>> +attributes #0 = { nounwind ssp uwtable "no-frame-pointer-elim"="true"
>> }
>> +attributes #1 = { nounwind readnone } attributes #2 = { nounwind }
>> +
>> +!llvm.dbg.cu = !{!0}
>> +!llvm.module.flags = !{!10, !11, !12}
>> +!llvm.ident = !{!13}
>> +
>> +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1,
>> producer:
>> +"clang version 3.9.0 ", isOptimized: true, runtimeVersion: 0,
>> +emissionKind: 1, enums: !2, subprograms: !3)
>> +!1 = !DIFile(filename: "test.c", directory: "/Volumes/Data/llvm")
>> +!2 = !{}
>> +!3 = !{!4}
>> +!4 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 3,
>> +type: !5, isLocal: false, isDefinition: true, scopeLine: 3,
>> +isOptimized: true, variables: !7)
>> +!5 = !DISubroutineType(types: !6)
>> +!6 = !{null}
>> +!7 = !{!8}
>> +!8 = !DILocalVariable(name: "a", scope: !4, file: !1, line: 5, type:
>> +!9)
>> +!9 = !DIBasicType(name: "int", size: 32, align: 32, encoding:
>> +DW_ATE_signed)
>> +!10 = !{i32 2, !"Dwarf Version", i32 2}
>> +!11 = !{i32 2, !"Debug Info Version", i32 3}
>> +!12 = !{i32 1, !"PIC Level", i32 2}
>> +!13 = !{!"clang version 3.9.0 "}
>> +!14 = !DILocation(line: 4, column: 3, scope: !4)
>> +!15 = !DILocation(line: 5, column: 11, scope: !4)
>> +!16 = !DIExpression()
>> +!17 = !DILocation(line: 5, column: 7, scope: !4)
>> +!18 = !DILocation(line: 6, column: 3, scope: !4)
>> +!19 = !DILocation(line: 7, column: 1, scope: !4)
>>
>> Modified: llvm/trunk/test/DebugInfo/X86/subregisters.ll
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/test/DebugInfo/X86/subregisters.ll?rev=262247&r1=262
>> 246&r2=262247&view=diff
>> =======================================================================
>> =======
>> --- llvm/trunk/test/DebugInfo/X86/subregisters.ll (original)
>> +++ llvm/trunk/test/DebugInfo/X86/subregisters.ll Mon Feb 29 13:49:46
>> +++ 2016
>> @@ -6,8 +6,13 @@
>> ;
>> ; rdar://problem/16015314
>> ;
>> -; CHECK: DW_AT_location [DW_FORM_block1] (<0x03> 54 93 04 )
>> -; CHECK: DW_AT_name [DW_FORM_strp]{{.*}} "a"
>> +; CHECK: .debug_info contents:
>> +; CHECK: DW_TAG_variable
>> +; CHECK-NEXT: DW_AT_location [DW_FORM_data4] (0x00000000)
>> +; CHECK-NEXT: DW_AT_name [DW_FORM_strp]{{.*}} "a"
>> +; CHECK: .debug_loc contents:
>> +; rsi, piece 0x00000004
>> +; CHECK: Location description: 54 93 04
>> ;
>> ; struct bar {
>> ; int a;
>>
>>
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