[llvm] r278703 - Local variables whose address is taken and passed on to a call are described
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 19 10:34:57 PDT 2016
Hello Wolfgang,
one problem I came across with this change is that
SelectionDAG::TransferDbgValues() currently doesn't handle FRAMEIX values at all which causes them to get dropped quite easily. I will try and come up with a testcase I can share, but in the meantime I was wondering if this is something you might already have patch in the pipeline for?
-- adrian
> On Aug 15, 2016, at 11:18 AM, Wolfgang Pieb via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>
> Author: wolfgangp
> Date: Mon Aug 15 13:18:26 2016
> New Revision: 278703
>
> URL: http://llvm.org/viewvc/llvm-project?rev=278703&view=rev
> Log:
> Local variables whose address is taken and passed on to a call are described
> in debug info using their stack slots instead of as an indirection of param reg + 0
> offset. This is done by detecting FrameIndexSDNodes in SelectionDAG and generating
> FrameIndexDbgValues for them. This ultimately generates DBG_VALUEs with stack
> location operands.
>
> Differential Revision: http://reviews.llvm.org/D23283
>
>
> Added:
> llvm/trunk/test/DebugInfo/X86/debug-loc-frame.ll
> Modified:
> llvm/trunk/include/llvm/IR/DebugInfoMetadata.h
> llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
> llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
> llvm/trunk/test/DebugInfo/AArch64/coalescing.ll
> llvm/trunk/test/DebugInfo/X86/array.ll
> llvm/trunk/test/DebugInfo/X86/bbjoin.ll
> llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll
>
> Modified: llvm/trunk/include/llvm/IR/DebugInfoMetadata.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/DebugInfoMetadata.h?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/IR/DebugInfoMetadata.h (original)
> +++ llvm/trunk/include/llvm/IR/DebugInfoMetadata.h Mon Aug 15 13:18:26 2016
> @@ -2155,6 +2155,11 @@ public:
> static bool classof(const Metadata *MD) {
> return MD->getMetadataID() == DIExpressionKind;
> }
> +
> + /// \brief Is the first element a DW_OP_deref?.
> + bool startsWithDeref() const {
> + return getNumElements() > 0 && getElement(0) == dwarf::DW_OP_deref;
> + }
> };
>
> class DIObjCProperty : public DINode {
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Mon Aug 15 13:18:26 2016
> @@ -1020,8 +1020,7 @@ void SelectionDAGBuilder::resolveDanglin
> if (Val.getNode()) {
> if (!EmitFuncArgumentDbgValue(V, Variable, Expr, dl, Offset, false,
> Val)) {
> - SDV = DAG.getDbgValue(Variable, Expr, Val.getNode(), Val.getResNo(),
> - false, Offset, dl, DbgSDNodeOrder);
> + SDV = getDbgValue(Val, Variable, Expr, Offset, dl, DbgSDNodeOrder);
> DAG.AddDbgValue(SDV, Val.getNode(), false);
> }
> } else
> @@ -4742,6 +4741,32 @@ bool SelectionDAGBuilder::EmitFuncArgume
> return true;
> }
>
> +/// Return the appropriate SDDbgValue based on N.
> +SDDbgValue *SelectionDAGBuilder::getDbgValue(SDValue N,
> + DILocalVariable *Variable,
> + DIExpression *Expr, int64_t Offset,
> + DebugLoc dl,
> + unsigned DbgSDNodeOrder) {
> + SDDbgValue *SDV;
> + auto *FISDN = dyn_cast<FrameIndexSDNode>(N.getNode());
> + if (FISDN && Expr->startsWithDeref()) {
> + // Construct a FrameIndexDbgValue for FrameIndexSDNodes so we can describe
> + // stack slot locations as such instead of as indirectly addressed
> + // locations.
> + ArrayRef<uint64_t> TrailingElements(Expr->elements_begin() + 1,
> + Expr->elements_end());
> + DIExpression *DerefedDIExpr =
> + DIExpression::get(*DAG.getContext(), TrailingElements);
> + int FI = FISDN->getIndex();
> + SDV = DAG.getFrameIndexDbgValue(Variable, DerefedDIExpr, FI, 0, dl,
> + DbgSDNodeOrder);
> + } else {
> + SDV = DAG.getDbgValue(Variable, Expr, N.getNode(), N.getResNo(), false,
> + Offset, dl, DbgSDNodeOrder);
> + }
> + return SDV;
> +}
> +
> // VisualStudio defines setjmp as _setjmp
> #if defined(_MSC_VER) && defined(setjmp) && \
> !defined(setjmp_undefined_for_msvc)
> @@ -4943,8 +4968,7 @@ SelectionDAGBuilder::visitIntrinsicCall(
> if (N.getNode()) {
> if (!EmitFuncArgumentDbgValue(V, Variable, Expression, dl, Offset,
> false, N)) {
> - SDV = DAG.getDbgValue(Variable, Expression, N.getNode(), N.getResNo(),
> - false, Offset, dl, SDNodeOrder);
> + SDV = getDbgValue(N, Variable, Expression, Offset, dl, SDNodeOrder);
> DAG.AddDbgValue(SDV, N.getNode(), false);
> }
> } else if (!V->use_empty() ) {
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h Mon Aug 15 13:18:26 2016
> @@ -942,6 +942,11 @@ private:
> /// Update the DAG and DAG builder with the relevant information after
> /// a new root node has been created which could be a tail call.
> void updateDAGForMaybeTailCall(SDValue MaybeTC);
> +
> + /// Return the appropriate SDDbgValue based on N.
> + SDDbgValue *getDbgValue(SDValue N, DILocalVariable *Variable,
> + DIExpression *Expr, int64_t Offset, DebugLoc dl,
> + unsigned DbgSDNodeOrder);
> };
>
> /// RegsForValue - This struct represents the registers (physical or virtual)
>
> Modified: llvm/trunk/test/DebugInfo/AArch64/coalescing.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/AArch64/coalescing.ll?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/AArch64/coalescing.ll (original)
> +++ llvm/trunk/test/DebugInfo/AArch64/coalescing.ll Mon Aug 15 13:18:26 2016
> @@ -25,7 +25,8 @@ entry:
> ; CHECK-NEXT: DW_AT_location
> ; CHECK-NEXT: DW_AT_name {{.*}}"size"
> ; CHECK: .debug_loc contents:
> - ; CHECK: Location description: 70 00
> + ; Expecting the encoding for sp+12: DW_OP_breg31 0c
> + ; CHECK: Location description: 8f 0c
> ret void, !dbg !18
> }
>
>
> Modified: llvm/trunk/test/DebugInfo/X86/array.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/array.ll?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/array.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/array.ll Mon Aug 15 13:18:26 2016
> @@ -16,9 +16,7 @@
> ; Test that we only emit register-indirect locations for the array array.
> ; rdar://problem/14874886
> ;
> -; FIXME: If we described this location as RSP-relative instead of RDI-relative
> -; the live range would be larger.
> -; CHECK: ##DEBUG_VALUE: main:array <- [%RDI+0]
> +; CHECK: ##DEBUG_VALUE: main:array <- [%RSP+0]
> ; CHECK-NOT: ##DEBUG_VALUE: main:array <- %R{{.*}}
> 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/bbjoin.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/bbjoin.ll?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/bbjoin.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/bbjoin.ll Mon Aug 15 13:18:26 2016
> @@ -12,7 +12,7 @@
> ; CHECK: ![[X:.*]] = !DILocalVariable(name: "x",
> ; CHECK: bb.0.entry:
> ; CHECK: DBG_VALUE 23, 0, ![[X]],
> -; CHECK: DBG_VALUE debug-use %rdi, debug-use _, ![[X]]
> +; CHECK: DBG_VALUE %rsp, 4, ![[X]]
> ; CHECK: bb.1.if.then:
> ; CHECK: DBG_VALUE 43, 0, ![[X]],
> ; CHECK: bb.2.if.end:
>
> Modified: llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll?rev=278703&r1=278702&r2=278703&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/dbg-value-const-byref.ll Mon Aug 15 13:18:26 2016
> @@ -41,7 +41,8 @@
> ; rdi+0
> ; CHECK: Beginning address offset: [[R1]]
> ; CHECK: Ending address offset: [[R2:.*]]
> -; CHECK: Location description: 75 00
> +; CHECK: Location description: 77 04
> +; rsp+4
> ;
> target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
> target triple = "x86_64-apple-macosx10.9.0"
>
> Added: llvm/trunk/test/DebugInfo/X86/debug-loc-frame.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/debug-loc-frame.ll?rev=278703&view=auto
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/debug-loc-frame.ll (added)
> +++ llvm/trunk/test/DebugInfo/X86/debug-loc-frame.ll Mon Aug 15 13:18:26 2016
> @@ -0,0 +1,113 @@
> +; REQUIRES: object-emission
> +
> +; Check that when variables are allocated on the stack we generate debug locations
> +; for the stack location directly instead of generating a register+offset indirection.
> +
> +; RUN: %llc_dwarf -O2 -filetype=obj -disable-post-ra < %s | llvm-dwarfdump - | FileCheck %s
> +;
> +; int data = 17;
> +; int sum = 0;
> +; int zero = 0;
> +; int *ptr;
> +;
> +; extern void foo(int i, int *p);
> +;
> +; int main()
> +; {
> +; int val;
> +; val = data;
> +; foo(1, &val);
> +; foo(2, &data);
> +; return zero;
> +; }
> +;
> +; CHECK: .debug_info contents
> +; CHECK: DW_TAG_subprogram
> +; CHECK-NOT: NULL
> +; CHECK: DW_TAG_variable
> +; CHECK: DW_AT_location [DW_FORM_sec_offset] ([[DEBUGLOCOFFSET:0x[0-9a-f]+]]){{[[:space:]].*}}"val"
> +
> +; See that 'val' has at least one location entry with a DW_op_breg? operand.
> +; The DWARF DW_op_breg* ops are encoded from 0x70 to 0x8f, but checking for an
> +; op in the range from 0x70 to 0x7f should suffice because that range covers
> +; all integer GPRs.
> +;
> +; CHECK: .debug_loc contents:
> +; CHECK-NOT: .debug{{.*}} contents
> +; CHECK: [[DEBUGLOCOFFSET]]: Beginning
> +; CHECK-NOT: {{0x[0-9a-f]+}}: Beginning
> +; CHECK: Location description: 7{{[0-9a-f] .*}}
> +
> +; ModuleID = 'frame.c'
> +source_filename = "frame.c"
> +
> + at data = global i32 17, align 4
> + at sum = local_unnamed_addr global i32 0, align 4
> + at zero = local_unnamed_addr global i32 0, align 4
> + at ptr = common local_unnamed_addr global i32* null, align 8
> +
> +; Function Attrs: nounwind uwtable
> +define i32 @main() local_unnamed_addr !dbg !13 {
> +entry:
> + %val = alloca i32, align 4
> + %0 = bitcast i32* %val to i8*, !dbg !18
> + call void @llvm.lifetime.start(i64 4, i8* %0), !dbg !18
> + %1 = load i32, i32* @data, align 4, !dbg !19, !tbaa !20
> + tail call void @llvm.dbg.value(metadata i32 %1, i64 0, metadata !17, metadata !24), !dbg !25
> + store i32 %1, i32* %val, align 4, !dbg !26, !tbaa !20
> + tail call void @llvm.dbg.value(metadata i32* %val, i64 0, metadata !17, metadata !27), !dbg !25
> + call void @foo(i32 1, i32* nonnull %val), !dbg !28
> + call void @foo(i32 2, i32* nonnull @data), !dbg !29
> + %2 = load i32, i32* @zero, align 4, !dbg !30, !tbaa !20
> + call void @llvm.lifetime.end(i64 4, i8* %0), !dbg !31
> + ret i32 %2, !dbg !32
> +}
> +
> +; Function Attrs: argmemonly nounwind
> +declare void @llvm.lifetime.start(i64, i8* nocapture)
> +
> +declare void @foo(i32, i32*) local_unnamed_addr
> +
> +; Function Attrs: argmemonly nounwind
> +declare void @llvm.lifetime.end(i64, i8* nocapture)
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!10, !11}
> +!llvm.ident = !{!12}
> +
> +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 (trunk 273961)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3)
> +!1 = !DIFile(filename: "frame.c", directory: "/home/user/test")
> +!2 = !{}
> +!3 = !{!4, !6, !7, !8}
> +!4 = distinct !DIGlobalVariable(name: "data", scope: !0, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, variable: i32* @data)
> +!5 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
> +!6 = distinct !DIGlobalVariable(name: "sum", scope: !0, file: !1, line: 2, type: !5, isLocal: false, isDefinition: true, variable: i32* @sum)
> +!7 = distinct !DIGlobalVariable(name: "zero", scope: !0, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, variable: i32* @zero)
> +!8 = distinct !DIGlobalVariable(name: "ptr", scope: !0, file: !1, line: 4, type: !9, isLocal: false, isDefinition: true, variable: i32** @ptr)
> +!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64, align: 64)
> +!10 = !{i32 2, !"Dwarf Version", i32 4}
> +!11 = !{i32 2, !"Debug Info Version", i32 3}
> +!12 = !{!"clang version 3.9.0 (trunk 273961)"}
> +!13 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 8, type: !14, isLocal: false, isDefinition: true, scopeLine: 9, isOptimized: true, unit: !0, variables: !16)
> +!14 = !DISubroutineType(types: !15)
> +!15 = !{!5}
> +!16 = !{!17}
> +!17 = !DILocalVariable(name: "val", scope: !13, file: !1, line: 10, type: !5)
> +!18 = !DILocation(line: 10, column: 3, scope: !13)
> +!19 = !DILocation(line: 11, column: 9, scope: !13)
> +!20 = !{!21, !21, i64 0}
> +!21 = !{!"int", !22, i64 0}
> +!22 = !{!"omnipotent char", !23, i64 0}
> +!23 = !{!"Simple C/C++ TBAA"}
> +!24 = !DIExpression()
> +!25 = !DILocation(line: 10, column: 7, scope: !13)
> +!26 = !DILocation(line: 11, column: 7, scope: !13)
> +!27 = !DIExpression(DW_OP_deref)
> +!28 = !DILocation(line: 12, column: 3, scope: !13)
> +!29 = !DILocation(line: 13, column: 3, scope: !13)
> +!30 = !DILocation(line: 14, column: 10, scope: !13)
> +!31 = !DILocation(line: 15, column: 1, scope: !13)
> +!32 = !DILocation(line: 14, column: 3, scope: !13)
>
>
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