commit 2f3f76fdb14a25fa27773bf415f61d7b10d53d62
author David Blaikie <dblaikie@gmail.com> Thu Aug 21 22:45:21 2014 +0000
committer David Blaikie <dblaikie@gmail.com> Thu Aug 21 22:45:21 2014 +0000
tree 08752e73a58574306840eb1ead039fd731e07a3d
parent 3e9af0dd1d1b6c5ce4164b9eedda7512b4761027

Use DILexicalBlockFile, rather than DILexicalBlock, to track discriminator changes to ensure discriminator changes don't introduce new DWARF DW_TAG_lexical_blocks.

Somewhat unnoticed in the original implementation of discriminators, but
it could cause instructions to end up in new, small,
DW_TAG_lexical_blocks due to the use of DILexicalBlock to track
discriminator changes.

Instead, use DILexicalBlockFile which we already use to track file
changes without introducing new scopes, so it works well to track
discriminator changes in the same way.

llvm-svn: 216239

llvm/docs/SourceLevelDebugging.rst

diff --git a/llvm/docs/SourceLevelDebugging.rst b/llvm/docs/SourceLevelDebugging.rst
index f76202a..f7b62cb 100644
--- a/llvm/docs/SourceLevelDebugging.rst
+++ b/llvm/docs/SourceLevelDebugging.rst
@@ -320,7 +320,6 @@
     metadata, ;; Reference to context descriptor
     i32,      ;; Line number
     i32,      ;; Column number
-    i32,      ;; DWARF path discriminator value
     i32       ;; Unique ID to identify blocks from a template function
   }
 
@@ -334,6 +333,7 @@
     i32,      ;; Tag = 11 (DW_TAG_lexical_block)
     metadata, ;; Source directory (including trailing slash) & file pair
     metadata  ;; Reference to the scope we're annotating with a file change
+    i32,      ;; DWARF path discriminator value
   }
 
 This descriptor provides a wrapper around a lexical scope to handle file
@@ -733,8 +733,7 @@
   !15 = metadata !{i32 786688, metadata !16, metadata !"Z", metadata !5, i32 5,
                    metadata !11, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [Z] \
                      [line 5]
-  !16 = metadata !{i32 786443, metadata !1, metadata !4, i32 4, i32 0, i32 0,
-                   i32 0} \
+  !16 = metadata !{i32 786443, metadata !1, metadata !4, i32 4, i32 0, i32 0} \
                    ; [ DW_TAG_lexical_block ] [/private/tmp/t.c]
   !17 = metadata !{i32 5, i32 0, metadata !16, null}
   !18 = metadata !{i32 6, i32 0, metadata !16, null}
@@ -786,8 +785,7 @@
 
 .. code-block:: llvm
 
-  !16 = metadata !{i32 786443, metadata !1, metadata !4, i32 4, i32 0, i32 0,
-                   i32 0}
+  !16 = metadata !{i32 786443, metadata !1, metadata !4, i32 4, i32 0, i32 0} \
                    ; [ DW_TAG_lexical_block ] [/private/tmp/t.c]
   !17 = metadata !{i32 5, i32 0, metadata !16, null}