[CGDebugInfo] Emit subprograms for decls when AT_tail_call is understood
Currently, clang emits subprograms for declared functions when the target debugger or DWARF standard is known to support entry values (DW_OP_entry_value & the GNU equivalent). Treat DW_AT_tail_call the same way to allow debuggers to follow cross-TU tail calls. Pre-patch debug session with a cross-TU tail call: ``` * frame #0: 0x0000000100000fa4 main`target at b.c:4:3 [opt] frame #1: 0x0000000100000f99 main`main at a.c:8:10 [opt] ``` Post-patch (note that the tail-calling frame, "helper", is visible): ``` * frame #0: 0x0000000100000fa4 main`target at b.c:4:3 [opt] frame #1: 0x0000000100000f80 main`helper [opt] [artificial] frame #2: 0x0000000100000f99 main`main at a.c:8:10 [opt] ``` rdar://46577651 Differential Revision: https://reviews.llvm.org/D69743
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@ -3748,9 +3748,7 @@ void CGDebugInfo::EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
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void CGDebugInfo::EmitFuncDeclForCallSite(llvm::CallBase *CallOrInvoke,
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void CGDebugInfo::EmitFuncDeclForCallSite(llvm::CallBase *CallOrInvoke,
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QualType CalleeType,
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QualType CalleeType,
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const FunctionDecl *CalleeDecl) {
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const FunctionDecl *CalleeDecl) {
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auto &CGOpts = CGM.getCodeGenOpts();
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if (!CallOrInvoke || getCallSiteRelatedAttrs() == llvm::DINode::FlagZero)
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if (!CGOpts.EnableDebugEntryValues || !CGM.getLangOpts().Optimize ||
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!CallOrInvoke)
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return;
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return;
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auto *Func = CallOrInvoke->getCalledFunction();
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auto *Func = CallOrInvoke->getCalledFunction();
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@ -4824,10 +4822,10 @@ llvm::DINode::DIFlags CGDebugInfo::getCallSiteRelatedAttrs() const {
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bool SupportsDWARFv4Ext =
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bool SupportsDWARFv4Ext =
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CGM.getCodeGenOpts().DwarfVersion == 4 &&
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CGM.getCodeGenOpts().DwarfVersion == 4 &&
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(CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB ||
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(CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB ||
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(CGM.getCodeGenOpts().EnableDebugEntryValues &&
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CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::GDB);
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CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::GDB));
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if (!SupportsDWARFv4Ext && CGM.getCodeGenOpts().DwarfVersion < 5)
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if (!SupportsDWARFv4Ext && CGM.getCodeGenOpts().DwarfVersion < 5 &&
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!CGM.getCodeGenOpts().EnableDebugEntryValues)
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return llvm::DINode::FlagZero;
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return llvm::DINode::FlagZero;
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return llvm::DINode::FlagAllCallsDescribed;
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return llvm::DINode::FlagAllCallsDescribed;
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@ -1,8 +1,21 @@
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// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -target x86_64-none-linux-gnu -S -emit-llvm %s -o - | FileCheck %s -check-prefix=CHECK-EXT
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// When entry values are emitted, expect a subprogram for extern decls so that
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// CHECK-EXT: !DISubprogram(name: "fn1"
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// the dwarf generator can describe call site parameters at extern call sites.
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//
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// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -target x86_64-none-linux-gnu -S -emit-llvm %s -o - | FileCheck %s -check-prefix=ENTRY-VAL
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// ENTRY-VAL: !DISubprogram(name: "fn1"
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// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -S -emit-llvm %s -o - | FileCheck %s
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// Similarly, when the debugger tuning is gdb, expect a subprogram for extern
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// CHECK-NOT: !DISubprogram(name: "fn1"
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// decls so that the dwarf generator can describe information needed for tail
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// call frame reconstrution.
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//
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// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -ggdb -S -emit-llvm %s -o - | FileCheck %s -check-prefix=GDB
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// GDB: !DISubprogram(name: "fn1"
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//
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// Do not emit a subprogram for extern decls when entry values are disabled and
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// the tuning is not set to gdb.
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//
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// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -gsce -S -emit-llvm %s -o - | FileCheck %s -check-prefix=SCE
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// SCE-NOT: !DISubprogram(name: "fn1"
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extern int fn1(int a, int b);
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extern int fn1(int a, int b);
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@ -56,6 +56,7 @@
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// NO-ATTR-NOT: FlagAllCallsDescribed
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// NO-ATTR-NOT: FlagAllCallsDescribed
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// HAS-ATTR-DAG: DISubprogram(name: "declaration1", {{.*}}, flags: DIFlagPrototyped
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// HAS-ATTR-DAG: DISubprogram(name: "declaration2", {{.*}}, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition
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// HAS-ATTR-DAG: DISubprogram(name: "declaration2", {{.*}}, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition
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// HAS-ATTR-DAG: DISubprogram(name: "struct1", {{.*}}, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
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// HAS-ATTR-DAG: DISubprogram(name: "struct1", {{.*}}, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
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// HAS-ATTR-DAG: DISubprogram(name: "struct1", {{.*}}, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition
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// HAS-ATTR-DAG: DISubprogram(name: "struct1", {{.*}}, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition
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@ -25,6 +25,14 @@
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@sink = global i32 0, align 4, !dbg !0
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@sink = global i32 0, align 4, !dbg !0
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define void @__has_no_subprogram() {
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entry:
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%0 = load volatile i32, i32* @sink, align 4
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%inc = add nsw i32 %0, 1
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store volatile i32 %inc, i32* @sink, align 4
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ret void
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}
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; ASM: DW_TAG_subprogram
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; ASM: DW_TAG_subprogram
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; ASM: DW_AT_call_all_calls
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; ASM: DW_AT_call_all_calls
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; OBJ: [[bat_sp:.*]]: DW_TAG_subprogram
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; OBJ: [[bat_sp:.*]]: DW_TAG_subprogram
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@ -70,6 +78,7 @@ entry:
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; OBJ: DW_AT_call_tail_call
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; OBJ: DW_AT_call_tail_call
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define void @_Z3foov() !dbg !25 {
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define void @_Z3foov() !dbg !25 {
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entry:
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entry:
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tail call void @__has_no_subprogram()
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tail call void @_Z3barv(), !dbg !26
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tail call void @_Z3barv(), !dbg !26
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tail call void @_Z3batv(), !dbg !27
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tail call void @_Z3batv(), !dbg !27
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tail call void @_Z3barv(), !dbg !26
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tail call void @_Z3barv(), !dbg !26
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