[llvm] r344841 - DebugInfo: Use base address specifiers more aggressively

[David Blaikie via llvm-commits]

Author: dblaikie
Date: Sat Oct 20 02:16:49 2018
New Revision: 344841

URL: http://llvm.org/viewvc/llvm-project?rev=344841&view=rev
Log:
DebugInfo: Use base address specifiers more aggressively

Using a base address specifier even for a single-element range is a size
win for object files (7 words versus 8 words - more significant savings
if the debug info is compressed (since it's 3 words of uncompressable
reloc + 4 compressable words compared to 6 uncompressable reloc + 2
compressable words) - does trade off executable size increase though.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    llvm/trunk/test/DebugInfo/X86/range_reloc.ll

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=344841&r1=344840&r2=344841&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Sat Oct 20 02:16:49 2018
@@ -2163,7 +2163,7 @@ static void emitRangeList(DwarfDebug &DD
     // or optnone where there may be holes in a single CU's section
     // contributions.
     auto *Base = CUBase;
-    if (!Base && P.second.size() > 1 &&
+    if (!Base && (P.second.size() > 1 || DwarfVersion < 5) &&
         (UseDwarfRangesBaseAddressSpecifier || DwarfVersion >= 5)) {
       BaseIsSet = true;
       // FIXME/use care: This may not be a useful base address if it's not

Modified: llvm/trunk/test/DebugInfo/X86/range_reloc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/range_reloc.ll?rev=344841&r1=344840&r2=344841&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/range_reloc.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/range_reloc.ll Sat Oct 20 02:16:49 2018
@@ -16,8 +16,21 @@
 ; smaller (the growth of debug_ranges itself would be more significant).
 
 ; COMMON: {{^.Ldebug_ranges0}}
-; COMMON-NEXT:   .quad   .Lfunc_begin0
-; COMMON-NEXT:   .quad   .Lfunc_end0
+; NOBASE-NEXT:   .quad   .Lfunc_begin0
+; NOBASE-NEXT:   .quad   .Lfunc_end0
+; NOBASE-NEXT:   .quad   .Lfunc_begin1
+; NOBASE-NEXT:   .quad   .Lfunc_end1
+; NOBASE-NEXT:   .quad   .Lfunc_begin3
+; NOBASE-NEXT:   .quad   .Lfunc_end3
+; NOBASE-NEXT:   .quad   .Lfunc_begin4
+; NOBASE-NEXT:   .quad   .Lfunc_end4
+; NOBASE-NEXT:   .quad   .Lfunc_begin5
+; NOBASE-NEXT:   .quad   .Lfunc_end5
+
+; BASE-NEXT:   .quad   -1
+; BASE-NEXT:   .quad   .Lfunc_begin0
+; BASE-NEXT:   .quad   .Lfunc_begin0-.Lfunc_begin0
+; BASE-NEXT:   .quad   .Lfunc_end0-.Lfunc_begin0
 ; BASE-NEXT:   .quad   -1
 ; BASE-NEXT:   .quad   .Lfunc_begin1
 ; BASE-NEXT:   .quad   .Lfunc_begin1-.Lfunc_begin1
@@ -25,15 +38,13 @@
 ; BASE-NEXT:   .quad   .Lfunc_begin3-.Lfunc_begin1
 ; BASE-NEXT:   .quad   .Lfunc_end3-.Lfunc_begin1
 ; BASE-NEXT:   .quad   -1
-; BASE-NEXT:   .quad   0
-; NOBASE-NEXT:   .quad   .Lfunc_begin1
-; NOBASE-NEXT:   .quad   .Lfunc_end1
-; NOBASE-NEXT:   .quad   .Lfunc_begin3
-; NOBASE-NEXT:   .quad   .Lfunc_end3
-; COMMON-NEXT:   .quad   .Lfunc_begin4
-; COMMON-NEXT:   .quad   .Lfunc_end4
-; COMMON-NEXT:   .quad   .Lfunc_begin5
-; COMMON-NEXT:   .quad   .Lfunc_end5
+; BASE-NEXT:   .quad   .Lfunc_begin4
+; BASE-NEXT:   .quad   .Lfunc_begin4-.Lfunc_begin4
+; BASE-NEXT:   .quad   .Lfunc_end4-.Lfunc_begin4
+; BASE-NEXT:   .quad   -1
+; BASE-NEXT:   .quad   .Lfunc_begin5
+; BASE-NEXT:   .quad   .Lfunc_begin5-.Lfunc_begin5
+; BASE-NEXT:   .quad   .Lfunc_end5-.Lfunc_begin5
 ; COMMON-NEXT:   .quad   0
 ; COMMON-NEXT:   .quad   0