[llvm] r364039 - Fix a crash with assembler source and -g.
Paul Robinson via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 21 06:10:19 PDT 2019
Author: probinson
Date: Fri Jun 21 06:10:19 2019
New Revision: 364039
URL: http://llvm.org/viewvc/llvm-project?rev=364039&view=rev
Log:
Fix a crash with assembler source and -g.
llvm-mc or clang with -g normally produces debug info describing the
assembler source itself; however, if that source already contains some
.file/.loc directives, we should instead emit the debug info described
by those directives. For certain assembler sources seen in the wild
(particularly in the Chrome build) this was causing a crash due to
incorrect assumptions about legal sequences of assembler source text.
Fixes PR38994.
Differential Revision: https://reviews.llvm.org/D63573
Added:
llvm/trunk/test/MC/AsmParser/directive_file-g.s
Modified:
llvm/trunk/include/llvm/MC/MCDwarf.h
llvm/trunk/lib/MC/MCParser/AsmParser.cpp
Modified: llvm/trunk/include/llvm/MC/MCDwarf.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCDwarf.h?rev=364039&r1=364038&r2=364039&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCDwarf.h (original)
+++ llvm/trunk/include/llvm/MC/MCDwarf.h Fri Jun 21 06:10:19 2019
@@ -261,6 +261,14 @@ public:
HasSource = Source.hasValue();
}
+ void resetFileTable() {
+ MCDwarfDirs.clear();
+ MCDwarfFiles.clear();
+ RootFile.Name.clear();
+ resetMD5Usage();
+ HasSource = false;
+ }
+
private:
void emitV2FileDirTables(MCStreamer *MCOS) const;
void emitV5FileDirTables(MCStreamer *MCOS, Optional<MCDwarfLineStr> &LineStr) const;
@@ -326,12 +334,7 @@ public:
Header.HasSource = Source.hasValue();
}
- void resetRootFile() {
- assert(Header.MCDwarfFiles.empty());
- Header.RootFile.Name.clear();
- Header.resetMD5Usage();
- Header.HasSource = false;
- }
+ void resetFileTable() { Header.resetFileTable(); }
bool hasRootFile() const { return !Header.RootFile.Name.empty(); }
Modified: llvm/trunk/lib/MC/MCParser/AsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCParser/AsmParser.cpp?rev=364039&r1=364038&r2=364039&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCParser/AsmParser.cpp (original)
+++ llvm/trunk/lib/MC/MCParser/AsmParser.cpp Fri Jun 21 06:10:19 2019
@@ -3395,9 +3395,9 @@ bool AsmParser::parseDirectiveFile(SMLoc
} else {
// In case there is a -g option as well as debug info from directive .file,
// we turn off the -g option, directly use the existing debug info instead.
- // Also reset any implicit ".file 0" for the assembler source.
+ // Throw away any implicit file table for the assembler source.
if (Ctx.getGenDwarfForAssembly()) {
- Ctx.getMCDwarfLineTable(0).resetRootFile();
+ Ctx.getMCDwarfLineTable(0).resetFileTable();
Ctx.setGenDwarfForAssembly(false);
}
Added: llvm/trunk/test/MC/AsmParser/directive_file-g.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/AsmParser/directive_file-g.s?rev=364039&view=auto
==============================================================================
--- llvm/trunk/test/MC/AsmParser/directive_file-g.s (added)
+++ llvm/trunk/test/MC/AsmParser/directive_file-g.s Fri Jun 21 06:10:19 2019
@@ -0,0 +1,24 @@
+## Make sure that using -g (or equivalent) on an asm file that already has
+## debug-info directives in it will correctly ignore the -g and produce
+## debug info corresponding to the directives in the source.
+## Note gcc accepts ".file 1" after a label, although not after an opcode.
+## If no other directives appear, gcc emits no debug info at all.
+
+# RUN: llvm-mc -g -triple i386-unknown-unknown -filetype=obj %s -o %t
+# RUN: llvm-dwarfdump -debug-info -debug-line %t | FileCheck %s
+
+foo:
+ .file 1 "a.c"
+ .loc 1 1 1
+ nop
+
+# CHECK: .debug_info
+## gcc does generate a DW_TAG_compile_unit in this case, with or without
+## -g on the command line, but we do not.
+# CHECK-EMPTY:
+# CHECK_NEXT: .debug_line
+# CHECK: file_names[ 1]:
+# CHECK-NEXT: name: "a.c"
+# CHECK-NEXT: dir_index: 0
+# CHECK: 0x{{0+}}0 1 1 1 0 0 is_stmt
+# CHECK: 0x{{0+}}1 1 1 1 0 0 is_stmt end_sequence
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