[clang] a5c8ec4 - [CGDebugInfo] Emit subprograms for decls when AT_tail_call is understood
Vedant Kumar via cfe-commits
cfe-commits at lists.llvm.org
Mon Nov 4 15:14:33 PST 2019
Author: Vedant Kumar
Date: 2019-11-04T15:14:24-08:00
New Revision: a5c8ec4baa2c00d8dbca36ffd236a40f9e0c07ed
URL: https://github.com/llvm/llvm-project/commit/a5c8ec4baa2c00d8dbca36ffd236a40f9e0c07ed
DIFF: https://github.com/llvm/llvm-project/commit/a5c8ec4baa2c00d8dbca36ffd236a40f9e0c07ed.diff
LOG: [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
Added:
Modified:
clang/lib/CodeGen/CGDebugInfo.cpp
clang/test/CodeGen/debug-info-extern-call.c
clang/test/CodeGenCXX/dbg-info-all-calls-described.cpp
llvm/test/DebugInfo/X86/dwarf-callsite-related-attrs.ll
Removed:
################################################################################
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index e0bb3fda7acf..c0c8fd3c8f16 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3748,9 +3748,7 @@ void CGDebugInfo::EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc,
void CGDebugInfo::EmitFuncDeclForCallSite(llvm::CallBase *CallOrInvoke,
QualType CalleeType,
const FunctionDecl *CalleeDecl) {
- auto &CGOpts = CGM.getCodeGenOpts();
- if (!CGOpts.EnableDebugEntryValues || !CGM.getLangOpts().Optimize ||
- !CallOrInvoke)
+ if (!CallOrInvoke || getCallSiteRelatedAttrs() == llvm::DINode::FlagZero)
return;
auto *Func = CallOrInvoke->getCalledFunction();
@@ -4824,10 +4822,10 @@ llvm::DINode::DIFlags CGDebugInfo::getCallSiteRelatedAttrs() const {
bool SupportsDWARFv4Ext =
CGM.getCodeGenOpts().DwarfVersion == 4 &&
(CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB ||
- (CGM.getCodeGenOpts().EnableDebugEntryValues &&
- CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::GDB));
+ CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::GDB);
- if (!SupportsDWARFv4Ext && CGM.getCodeGenOpts().DwarfVersion < 5)
+ if (!SupportsDWARFv4Ext && CGM.getCodeGenOpts().DwarfVersion < 5 &&
+ !CGM.getCodeGenOpts().EnableDebugEntryValues)
return llvm::DINode::FlagZero;
return llvm::DINode::FlagAllCallsDescribed;
diff --git a/clang/test/CodeGen/debug-info-extern-call.c b/clang/test/CodeGen/debug-info-extern-call.c
index e35669b78f93..7f58fe59a635 100644
--- a/clang/test/CodeGen/debug-info-extern-call.c
+++ b/clang/test/CodeGen/debug-info-extern-call.c
@@ -1,8 +1,21 @@
-// 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
-// CHECK-EXT: !DISubprogram(name: "fn1"
+// When entry values are emitted, expect a subprogram for extern decls so that
+// the dwarf generator can describe call site parameters at extern call sites.
+//
+// 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
+// ENTRY-VAL: !DISubprogram(name: "fn1"
-// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -S -emit-llvm %s -o - | FileCheck %s
-// CHECK-NOT: !DISubprogram(name: "fn1"
+// Similarly, when the debugger tuning is gdb, expect a subprogram for extern
+// decls so that the dwarf generator can describe information needed for tail
+// call frame reconstrution.
+//
+// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -ggdb -S -emit-llvm %s -o - | FileCheck %s -check-prefix=GDB
+// GDB: !DISubprogram(name: "fn1"
+//
+// Do not emit a subprogram for extern decls when entry values are disabled and
+// the tuning is not set to gdb.
+//
+// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -gsce -S -emit-llvm %s -o - | FileCheck %s -check-prefix=SCE
+// SCE-NOT: !DISubprogram(name: "fn1"
extern int fn1(int a, int b);
diff --git a/clang/test/CodeGenCXX/dbg-info-all-calls-described.cpp b/clang/test/CodeGenCXX/dbg-info-all-calls-described.cpp
index 1cb2b6c609f3..667c2469b55e 100644
--- a/clang/test/CodeGenCXX/dbg-info-all-calls-described.cpp
+++ b/clang/test/CodeGenCXX/dbg-info-all-calls-described.cpp
@@ -56,6 +56,7 @@
// NO-ATTR-NOT: FlagAllCallsDescribed
+// HAS-ATTR-DAG: DISubprogram(name: "declaration1", {{.*}}, flags: DIFlagPrototyped
// HAS-ATTR-DAG: DISubprogram(name: "declaration2", {{.*}}, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition
// HAS-ATTR-DAG: DISubprogram(name: "struct1", {{.*}}, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
// HAS-ATTR-DAG: DISubprogram(name: "struct1", {{.*}}, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition
diff --git a/llvm/test/DebugInfo/X86/dwarf-callsite-related-attrs.ll b/llvm/test/DebugInfo/X86/dwarf-callsite-related-attrs.ll
index c37ce1eb7fbe..33e06faba57b 100644
--- a/llvm/test/DebugInfo/X86/dwarf-callsite-related-attrs.ll
+++ b/llvm/test/DebugInfo/X86/dwarf-callsite-related-attrs.ll
@@ -25,6 +25,14 @@
@sink = global i32 0, align 4, !dbg !0
+define void @__has_no_subprogram() {
+entry:
+ %0 = load volatile i32, i32* @sink, align 4
+ %inc = add nsw i32 %0, 1
+ store volatile i32 %inc, i32* @sink, align 4
+ ret void
+}
+
; ASM: DW_TAG_subprogram
; ASM: DW_AT_call_all_calls
; OBJ: [[bat_sp:.*]]: DW_TAG_subprogram
@@ -70,6 +78,7 @@ entry:
; OBJ: DW_AT_call_tail_call
define void @_Z3foov() !dbg !25 {
entry:
+ tail call void @__has_no_subprogram()
tail call void @_Z3barv(), !dbg !26
tail call void @_Z3batv(), !dbg !27
tail call void @_Z3barv(), !dbg !26
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