From 56262a74c315f7a654915ac6053d7d5a3b4f71d7 Mon Sep 17 00:00:00 2001
From: Leandro Vaz <leandrov@graphcore.ai>
Date: Thu, 21 May 2020 16:24:07 +0100
Subject: [PATCH] Fix debug line info when line markers are present inside
 macros.

Compiling assembly files when newlines are reduced to line markers within a `.macro` context will generate wrong information in `.debug_line` section.
This patch fixes this issue by evaluating line markers within the macro scope but not when they are used and evaluated.

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D80381
---
 llvm/lib/MC/MCParser/AsmParser.cpp               | 16 ++++++++++++----
 .../test/MC/AsmParser/line-marker-inside-macro.s | 14 ++++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/MC/AsmParser/line-marker-inside-macro.s

diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 1cb30ae3073e..9e92ce09986f 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -267,7 +267,7 @@ private:
   bool parseStatement(ParseStatementInfo &Info,
                       MCAsmParserSemaCallback *SI);
   bool parseCurlyBlockScope(SmallVectorImpl<AsmRewrite>& AsmStrRewrites);
-  bool parseCppHashLineFilenameComment(SMLoc L);
+  bool parseCppHashLineFilenameComment(SMLoc L, bool SaveLocInfo = true);
 
   void checkForBadMacro(SMLoc DirectiveLoc, StringRef Name, StringRef Body,
                         ArrayRef<MCAsmMacroParameter> Parameters);
@@ -1699,7 +1699,9 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
   StringRef IDVal;
   int64_t LocalLabelVal = -1;
   if (Lexer.is(AsmToken::HashDirective))
-    return parseCppHashLineFilenameComment(IDLoc);
+    return parseCppHashLineFilenameComment(IDLoc,
+                                           !isInsideMacroInstantiation());
+
   // Allow an integer followed by a ':' as a directional local label.
   if (Lexer.is(AsmToken::Integer)) {
     LocalLabelVal = getTok().getIntVal();
@@ -2294,7 +2296,7 @@ AsmParser::parseCurlyBlockScope(SmallVectorImpl<AsmRewrite> &AsmStrRewrites) {
 
 /// parseCppHashLineFilenameComment as this:
 ///   ::= # number "filename"
-bool AsmParser::parseCppHashLineFilenameComment(SMLoc L) {
+bool AsmParser::parseCppHashLineFilenameComment(SMLoc L, bool SaveLocInfo) {
   Lex(); // Eat the hash token.
   // Lexer only ever emits HashDirective if it fully formed if it's
   // done the checking already so this is an internal error.
@@ -2307,6 +2309,9 @@ bool AsmParser::parseCppHashLineFilenameComment(SMLoc L) {
   StringRef Filename = getTok().getString();
   Lex();
 
+  if (!SaveLocInfo)
+    return false;
+
   // Get rid of the enclosing quotes.
   Filename = Filename.substr(1, Filename.size() - 2);
 
@@ -4454,7 +4459,8 @@ bool AsmParser::parseDirectiveMacro(SMLoc DirectiveLoc) {
     if (getLexer().is(AsmToken::Eof))
       return Error(DirectiveLoc, "no matching '.endmacro' in definition");
 
-    // Otherwise, check whether we have reach the .endmacro.
+    // Otherwise, check whether we have reach the .endmacro or the start of a
+    // preprocessor line marker.
     if (getLexer().is(AsmToken::Identifier)) {
       if (getTok().getIdentifier() == ".endm" ||
           getTok().getIdentifier() == ".endmacro") {
@@ -4474,6 +4480,8 @@ bool AsmParser::parseDirectiveMacro(SMLoc DirectiveLoc) {
         // macro is expanded so just ignore them for now.
         ++MacroDepth;
       }
+    } else if (Lexer.is(AsmToken::HashDirective)) {
+      (void)parseCppHashLineFilenameComment(getLexer().getLoc());
     }
 
     // Otherwise, scan til the end of the statement.
diff --git a/llvm/test/MC/AsmParser/line-marker-inside-macro.s b/llvm/test/MC/AsmParser/line-marker-inside-macro.s
new file mode 100644
index 000000000000..ee6ddb8f5835
--- /dev/null
+++ b/llvm/test/MC/AsmParser/line-marker-inside-macro.s
@@ -0,0 +1,14 @@
+// RUN: llvm-mc -triple i386-unknown-unknown --filetype=obj -g %s -o %t
+// RUN: llvm-dwarfdump -a %t | FileCheck %s
+
+.macro FOO
+# 100 "./line-marker-inside-macro.s"
+.endm
+
+
+
+FOO
+  mov %eax, 0
+
+// CHECK:      0x0000000000000000 105 0 1 0 0 is_stmt
+// CHECK-NEXT: 0x0000000000000005 105 0 1 0 0 is_stmt end_sequence