vendor/llvm/llvm-trunk-r300890

1 files changed, 19 insertions, 3 deletions

diff --git a/docs/SourceLevelDebugging.rst b/docs/SourceLevelDebugging.rst
index 41f8dbfab3dc..a9f5c3a08147 100644
--- a/docs/SourceLevelDebugging.rst
+++ b/docs/SourceLevelDebugging.rst
@@ -180,11 +180,27 @@ provide debug information at various points in generated code.
 
   void @llvm.dbg.declare(metadata, metadata, metadata)
 
-This intrinsic provides information about a local element (e.g., variable).
-The first argument is metadata holding the alloca for the variable.  The second
+This intrinsic provides information about a local element (e.g., variable).  The
+first argument is metadata holding the alloca for the variable.  The second
 argument is a `local variable <LangRef.html#dilocalvariable>`_ containing a
 description of the variable.  The third argument is a `complex expression
-<LangRef.html#diexpression>`_.
+<LangRef.html#diexpression>`_.  An `llvm.dbg.declare` instrinsic describes the
+*location* of a source variable.
+
+.. code-block:: llvm
+
+    %i.addr = alloca i32, align 4
+    call void @llvm.dbg.declare(metadata i32* %i.addr, metadata !1, metadata !2), !dbg !3
+    !1 = !DILocalVariable(name: "i", ...) ; int i
+    !2 = !DIExpression()
+    !3 = !DILocation(...)
+    ...
+    %buffer = alloca [256 x i8], align 8
+    ; The address of i is buffer+64.
+    call void @llvm.dbg.declare(metadata [256 x i8]* %buffer, metadata !1, metadata !2)
+    !1 = !DILocalVariable(name: "i", ...) ; int i
+    !2 = !DIExpression(DW_OP_plus, 64)
+
 
 ``llvm.dbg.value``
 ^^^^^^^^^^^^^^^^^^