[llvm] r289620 - [DWARF] Preserve column number when emitting 'line 0' record

[Paul Robinson via llvm-commits]

Author: probinson
Date: Tue Dec 13 18:27:35 2016
New Revision: 289620

URL: http://llvm.org/viewvc/llvm-project?rev=289620&view=rev
Log:
[DWARF] Preserve column number when emitting 'line 0' record

Follow-up to r289256, address a FIXME to avoid resetting the column
number. This reduced .debug_line by 2.6% in a RelWithDebInfo
self-build of clang.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    llvm/trunk/test/CodeGen/X86/unknown-location.ll
    llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll
    llvm/trunk/test/DebugInfo/X86/tail-merge.ll

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=289620&r1=289619&r2=289620&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Tue Dec 13 18:27:35 2016
@@ -1048,11 +1048,16 @@ void DwarfDebug::beginInstruction(const
     //   location from the physically previous (maybe unrelated) block.
     if (UnknownLocations == Enable || PrevLabel ||
         (PrevInstBB && PrevInstBB != MI->getParent())) {
-      // Preserve the file number, if we can, to save space in the line table.
+      // Preserve the file and column numbers, if we can, to save space in
+      // the encoded line table.
       // Do not update PrevInstLoc, it remembers the last non-0 line.
-      // FIXME: Also preserve the column number, to save more space?
-      const MDNode *Scope = PrevInstLoc ? PrevInstLoc.getScope() : nullptr;
-      recordSourceLine(0, 0, Scope, 0);
+      const MDNode *Scope = nullptr;
+      unsigned Column = 0;
+      if (PrevInstLoc) {
+        Scope = PrevInstLoc.getScope();
+        Column = PrevInstLoc.getCol();
+      }
+      recordSourceLine(/*Line=*/0, Column, Scope, /*Flags=*/0);
     }
     return;
   }

Modified: llvm/trunk/test/CodeGen/X86/unknown-location.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/unknown-location.ll?rev=289620&r1=289619&r2=289620&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/unknown-location.ll (original)
+++ llvm/trunk/test/CodeGen/X86/unknown-location.ll Tue Dec 13 18:27:35 2016
@@ -1,11 +1,10 @@
 ; RUN: llc < %s -asm-verbose=false -mtriple=x86_64-apple-darwin10 -use-unknown-locations=Enable | FileCheck %s
 
 ; The divide instruction does not have a debug location. CodeGen should
-; represent this in the debug information. This is done by setting line
-; and column to 0
+; represent this in the debug information. This is done by setting line to 0.
 
 ;      CHECK:         leal
-; CHECK-NEXT:         .loc 1 0 0
+; CHECK-NEXT:         .loc 1 0 3
 ;      CHECK:         cltd
 ; CHECK-NEXT:         idivl
 ; CHECK-NEXT:         .loc 1 4 3

Modified: llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll?rev=289620&r1=289619&r2=289620&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/dwarf-no-source-loc.ll Tue Dec 13 18:27:35 2016
@@ -42,11 +42,11 @@ if.end:
 
 ; CHECK:      .loc 1 7 7
 ; CHECK-NOT:  .loc
-; CHECK:      .loc 1 0 0 is_stmt 0
+; CHECK:      .loc 1 0 7 is_stmt 0
 ; CHECK-NOT:  .loc
 ; CHECK:      .loc 2 20 5 is_stmt 1
 ; CHECK:      .LBB0_2:
-; CHECK-NEXT: .loc 2 0 0 is_stmt 0
+; CHECK-NEXT: .loc 2 0 5 is_stmt 0
 ; CHECK-NOT:  .loc
 ; CHECK:      .loc 1 10 3 is_stmt 1
 ;

Modified: llvm/trunk/test/DebugInfo/X86/tail-merge.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/tail-merge.ll?rev=289620&r1=289619&r2=289620&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/tail-merge.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/tail-merge.ll Tue Dec 13 18:27:35 2016
@@ -27,7 +27,7 @@
 ; CHECK: .loc	1 8 10
 ; CHECK: callq	bar
 ; CHECK: [[TAIL]]:
-; CHECK: .loc	1 0 0
+; CHECK: .loc	1 0
 ; CHECK: addl	[[REG]], %eax
 ; CHECK: .loc	1 9 3