<div dir="ltr">Looks good to me, please commit.<br><br>(test might do with an improvement - to make sure the attribute is appearing in the right place, I'd expect something like:<br><br>CHECK: DW_TAG_subprogram<br>CHECK-NOT: {{DW_TAG|NULL}}<div>CHECK: DW_AT_name {{.*}} "main"</div><div>CHECK-NOT: {{DW_TAG|NULL}}<br>CHECK: DW_AT_main_subprogram...<br><br>or the like.<br><br><div class="gmail_quote"><div dir="ltr">On Tue, Nov 22, 2016 at 11:22 PM Tom Tromey via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I'd like the Rust compiler to emit DW_AT_main_subprogram in its DWARF<br class="gmail_msg">
output, so that debuggers can find the user-provided main entry point.<br class="gmail_msg">
See <a href="https://github.com/rust-lang/rust/issues/32620" rel="noreferrer" class="gmail_msg" target="_blank">https://github.com/rust-lang/rust/issues/32620</a><br class="gmail_msg">
<br class="gmail_msg">
This patch adds support for DW_AT_main_subprogram to LLVM to support<br class="gmail_msg">
this effort.<br class="gmail_msg">
<br class="gmail_msg">
I've built and tested it on x86-64 Fedora 24.<br class="gmail_msg">
<br class="gmail_msg">
Note that while DWARF allows DW_AT_main_subprogram to appear on a<br class="gmail_msg">
DW_TAG_compile_unit DIE, I did not need this, so I've only implemented<br class="gmail_msg">
it for DW_TAG_subroutine.<br class="gmail_msg">
<br class="gmail_msg">
I've added a new test case, which I copied from version.ll and then<br class="gmail_msg">
modified to suit.<br class="gmail_msg">
<br class="gmail_msg">
Tom<br class="gmail_msg">
---<br class="gmail_msg">
include/llvm/IR/DebugInfoFlags.def | 3 ++-<br class="gmail_msg">
include/llvm/IR/DebugInfoMetadata.h | 1 +<br class="gmail_msg">
lib/CodeGen/AsmPrinter/DwarfUnit.cpp | 3 +++<br class="gmail_msg">
test/DebugInfo/Generic/mainsubprogram.ll | 31 +++++++++++++++++++++++++++++++<br class="gmail_msg">
4 files changed, 37 insertions(+), 1 deletion(-)<br class="gmail_msg">
create mode 100644 test/DebugInfo/Generic/mainsubprogram.ll<br class="gmail_msg">
<br class="gmail_msg">
diff --git a/include/llvm/IR/DebugInfoFlags.def b/include/llvm/IR/DebugInfoFlags.def<br class="gmail_msg">
index 013114c..87f3dc9 100644<br class="gmail_msg">
--- a/include/llvm/IR/DebugInfoFlags.def<br class="gmail_msg">
+++ b/include/llvm/IR/DebugInfoFlags.def<br class="gmail_msg">
@@ -41,6 +41,7 @@ HANDLE_DI_FLAG((3 << 16), VirtualInheritance)<br class="gmail_msg">
HANDLE_DI_FLAG((1 << 18), IntroducedVirtual)<br class="gmail_msg">
HANDLE_DI_FLAG((1 << 19), BitField)<br class="gmail_msg">
HANDLE_DI_FLAG((1 << 20), NoReturn)<br class="gmail_msg">
+HANDLE_DI_FLAG((1 << 21), MainSubprogram)<br class="gmail_msg">
<br class="gmail_msg">
// To avoid needing a dedicated value for IndirectVirtualBase, we use<br class="gmail_msg">
// the bitwise or of Virtual and FwdDecl, which does not otherwise<br class="gmail_msg">
@@ -50,7 +51,7 @@ HANDLE_DI_FLAG((1 << 2) | (1 << 5), IndirectVirtualBase)<br class="gmail_msg">
#ifdef DI_FLAG_LARGEST_NEEDED<br class="gmail_msg">
// intended to be used with ADT/BitmaskEnum.h<br class="gmail_msg">
// NOTE: always must be equal to largest flag, check this when adding new flag<br class="gmail_msg">
-HANDLE_DI_FLAG((1 << 20), Largest)<br class="gmail_msg">
+HANDLE_DI_FLAG((1 << 21), Largest)<br class="gmail_msg">
#undef DI_FLAG_LARGEST_NEEDED<br class="gmail_msg">
#endif<br class="gmail_msg">
<br class="gmail_msg">
diff --git a/include/llvm/IR/DebugInfoMetadata.h b/include/llvm/IR/DebugInfoMetadata.h<br class="gmail_msg">
index aaa0e0d..fcd4d08 100644<br class="gmail_msg">
--- a/include/llvm/IR/DebugInfoMetadata.h<br class="gmail_msg">
+++ b/include/llvm/IR/DebugInfoMetadata.h<br class="gmail_msg">
@@ -1420,6 +1420,7 @@ public:<br class="gmail_msg">
}<br class="gmail_msg">
bool isExplicit() const { return getFlags() & FlagExplicit; }<br class="gmail_msg">
bool isPrototyped() const { return getFlags() & FlagPrototyped; }<br class="gmail_msg">
+ bool isMainSubprogram() const { return getFlags() & FlagMainSubprogram; }<br class="gmail_msg">
<br class="gmail_msg">
/// Check if this is reference-qualified.<br class="gmail_msg">
///<br class="gmail_msg">
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp<br class="gmail_msg">
index a49518a..d2fbf0a 100644<br class="gmail_msg">
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp<br class="gmail_msg">
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp<br class="gmail_msg">
@@ -1282,6 +1282,9 @@ void DwarfUnit::applySubprogramAttributes(const DISubprogram *SP, DIE &SPDie,<br class="gmail_msg">
<br class="gmail_msg">
if (SP->isExplicit())<br class="gmail_msg">
addFlag(SPDie, dwarf::DW_AT_explicit);<br class="gmail_msg">
+<br class="gmail_msg">
+ if (SP->isMainSubprogram())<br class="gmail_msg">
+ addFlag(SPDie, dwarf::DW_AT_main_subprogram);<br class="gmail_msg">
}<br class="gmail_msg">
<br class="gmail_msg">
void DwarfUnit::constructSubrangeDIE(DIE &Buffer, const DISubrange *SR,<br class="gmail_msg">
diff --git a/test/DebugInfo/Generic/mainsubprogram.ll b/test/DebugInfo/Generic/mainsubprogram.ll<br class="gmail_msg">
new file mode 100644<br class="gmail_msg">
index 0000000..be843c4<br class="gmail_msg">
--- /dev/null<br class="gmail_msg">
+++ b/test/DebugInfo/Generic/mainsubprogram.ll<br class="gmail_msg">
@@ -0,0 +1,31 @@<br class="gmail_msg">
+; REQUIRES: object-emission<br class="gmail_msg">
+<br class="gmail_msg">
+; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t<br class="gmail_msg">
+; RUN: llvm-dwarfdump %t | FileCheck %s<br class="gmail_msg">
+<br class="gmail_msg">
+; Make sure we're emitting DW_AT_main_subprogram.<br class="gmail_msg">
+; CHECK: DW_AT_main_subprogram [DW_FORM_flag_present] (true)<br class="gmail_msg">
+<br class="gmail_msg">
+define i32 @main() #0 !dbg !4 {<br class="gmail_msg">
+entry:<br class="gmail_msg">
+ %retval = alloca i32, align 4<br class="gmail_msg">
+ store i32 0, i32* %retval<br class="gmail_msg">
+ ret i32 0, !dbg !10<br class="gmail_msg">
+}<br class="gmail_msg">
+<br class="gmail_msg">
+attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }<br class="gmail_msg">
+<br class="gmail_msg">
+!<a href="http://llvm.dbg.cu" rel="noreferrer" class="gmail_msg" target="_blank">llvm.dbg.cu</a> = !{!0}<br class="gmail_msg">
+!llvm.module.flags = !{!9, !11}<br class="gmail_msg">
+<br class="gmail_msg">
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang version 3.4 (trunk 185475)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)<br class="gmail_msg">
+!1 = !DIFile(filename: "CodeGen/dwarf-version.c", directory: "test")<br class="gmail_msg">
+!2 = !{}<br class="gmail_msg">
+!4 = distinct !DISubprogram(name: "main", line: 6, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped | DIFlagMainSubprogram, isOptimized: false, unit: !0, scopeLine: 6, file: !1, scope: !5, type: !6, variables: !2)<br class="gmail_msg">
+!5 = !DIFile(filename: "CodeGen/dwarf-version.c", directory: "test")<br class="gmail_msg">
+!6 = !DISubroutineType(types: !7)<br class="gmail_msg">
+!7 = !{!8}<br class="gmail_msg">
+!8 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)<br class="gmail_msg">
+!9 = !{i32 2, !"Dwarf Version", i32 4}<br class="gmail_msg">
+!10 = !DILocation(line: 7, scope: !4)<br class="gmail_msg">
+!11 = !{i32 1, !"Debug Info Version", i32 3}<br class="gmail_msg">
--<br class="gmail_msg">
2.7.4<br class="gmail_msg">
<br class="gmail_msg">
_______________________________________________<br class="gmail_msg">
llvm-commits mailing list<br class="gmail_msg">
<a href="mailto:llvm-commits@lists.llvm.org" class="gmail_msg" target="_blank">llvm-commits@lists.llvm.org</a><br class="gmail_msg">
<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits" rel="noreferrer" class="gmail_msg" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</a><br class="gmail_msg">
</blockquote></div></div></div>