[llvm] r224810 - IAS: correct debug line info for asm macros

[Saleem Abdulrasool]

Author: compnerd
Date: Wed Dec 24 00:32:43 2014
New Revision: 224810

URL: http://llvm.org/viewvc/llvm-project?rev=224810&view=rev
Log:
IAS: correct debug line info for asm macros

Correct the line information generation for preprocessed assembly.  Although we
tracked the source information for the macro instantiation, we failed to account
for the fact that we were instantiating a macro, which is populated into a new
buffer and that the line information would be relative to the definition rather
than the actual instantiation location.  This could cause the line number
associated with the statement to be very high due to wrapping of the difference
calculated for the preprocessor line information emitted into the stream.
Properly calculate the line for the macro instantiation, referencing the line
where the macro is actually used as GCC/gas do.

The test case uses x86, though the same problem exists on any other target using
the LLVM IAS.

Added:
    llvm/trunk/test/DebugInfo/X86/asm-macro-line-number.s
Modified:
    llvm/trunk/lib/MC/MCParser/AsmParser.cpp

Modified: llvm/trunk/lib/MC/MCParser/AsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCParser/AsmParser.cpp?rev=224810&r1=224809&r2=224810&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCParser/AsmParser.cpp (original)
+++ llvm/trunk/lib/MC/MCParser/AsmParser.cpp Wed Dec 24 00:32:43 2014
@@ -1595,14 +1595,18 @@ bool AsmParser::parseStatement(ParseStat
   // directive for the instruction.
   if (!HadError && getContext().getGenDwarfForAssembly() &&
       getContext().getGenDwarfSectionSyms().count(
-        getStreamer().getCurrentSection().first)) {
-
-    unsigned Line = SrcMgr.FindLineNumber(IDLoc, CurBuffer);
+          getStreamer().getCurrentSection().first)) {
+    unsigned Line;
+    if (ActiveMacros.empty())
+      Line = SrcMgr.FindLineNumber(IDLoc, CurBuffer);
+    else
+      Line = SrcMgr.FindLineNumber(ActiveMacros.back()->InstantiationLoc,
+                                   ActiveMacros.back()->ExitBuffer);
 
     // If we previously parsed a cpp hash file line comment then make sure the
     // current Dwarf File is for the CppHashFilename if not then emit the
     // Dwarf File table for it and adjust the line number for the .loc.
-    if (CppHashFilename.size() != 0) {
+    if (CppHashFilename.size()) {
       unsigned FileNumber = getStreamer().EmitDwarfFileDirective(
           0, StringRef(), CppHashFilename);
       getContext().setGenDwarfFileNumber(FileNumber);

Added: llvm/trunk/test/DebugInfo/X86/asm-macro-line-number.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/asm-macro-line-number.s?rev=224810&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/asm-macro-line-number.s (added)
+++ llvm/trunk/test/DebugInfo/X86/asm-macro-line-number.s Wed Dec 24 00:32:43 2014
@@ -0,0 +1,20 @@
+# RUN: llvm-mc -g -triple i686-linux-gnu -filetype asm -o - %s | FileCheck %s
+
+# 1 "reduced.S"
+# 1 "<built-in>" 1
+# 1 "reduced.S" 2
+
+ .macro return arg
+  movl %eax, \arg
+  retl
+ .endm
+
+function:
+ return 0
+
+# CHECK: .file 2 "reduced.S"
+# CHECK: .loc 2 8 0
+# CHECK: movl %eax, 0
+# CHECK: .loc 2 8 0
+# CHECK: retl
+