With the newly simplified SourceMgr interfaces and the generalized

SrcMgrDiagHandler, we can improve clang diagnostics for inline asm:
instead of reporting them on a source line of the original line,
we can report it on the correct line wherever the string literal came
from. For something like this:

void foo() {
  asm("push %rax\n"
      ".code32\n");
}

we used to get this: (note that the line in t.c isn't helpful)

t.c:4:7: error: warning: ignoring directive for now
  asm("push %rax\n"
      ^
<inline asm>:2:1: note: instantiated into assembly here
.code32
^

now we get:

t.c:5:8: error: warning: ignoring directive for now
      ".code32\n"
       ^
<inline asm>:2:1: note: instantiated into assembly here
.code32
^

Note that we're pointing to line 5 properly now.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119488 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LangRef.html

@@ -2625,8 +2625,8 @@ call void asm alignstack "eieio", ""()
 <div class="doc_text">
 
 <p>The call instructions that wrap inline asm nodes may have a "!srcloc" MDNode
-   attached to it that contains a constant integer.  If present, the code
-   generator will use the integer as the location cookie value when report
+   attached to it that contains a list of constant integers.  If present, the
+  code generator will use the integer as the location cookie value when report
    errors through the LLVMContext error reporting mechanisms.  This allows a
    front-end to correlate backend errors that occur with inline asm back to the
    source code that produced it.  For example:</p>
@@ -2638,7 +2638,8 @@ call void asm sideeffect "something bad", ""()<b>, !srcloc !42</b>
 </pre>
 
 <p>It is up to the front-end to make sense of the magic numbers it places in the
-   IR.</p>
+   IR.  If the MDNode contains multiple constants, the code generator will use
+   the one that corresponds to the line of the asm that the error occurs on.</p>
 
 </div>