Implement -Wframe-larger-than backend diagnostic

Add driver and frontend support for the GCC -Wframe-larger-than=bytes warning.
This is the first GCC-compatible backend diagnostic built around LLVM's
reporting feature.

This commit adds infrastructure to perform reverse lookup from mangled names
emitted after LLVM IR generation. We use that to resolve precise locations and
originating AST functions, lambdas or block declarations to produce seamless
codegen-guided diagnostics.

An associated change, StringMap now maintains unique mangled name strings
instead of allocating copies. This is a net memory saving in C++ and a small
hit for C where we no longer reuse IdentifierInfo storage, pending further
optimisation.

llvm-svn: 210293

1 files changed, 3 insertions, 6 deletions

diff --git a/clang/test/Frontend/backend-diagnostic.c b/clang/test/Frontend/backend-diagnostic.c
index 8b61c0350ec..d6fe48bc9c5 100644
--- a/clang/test/Frontend/backend-diagnostic.c
+++ b/clang/test/Frontend/backend-diagnostic.c
@@ -11,16 +11,13 @@
 // RUN: not %clang_cc1 %s -mllvm -warn-stack-size=0 -no-integrated-as -S -o - -triple=i386-apple-darwin -Wno-frame-larger-than 2> %t.err
 // RUN: FileCheck < %t.err %s --check-prefix=IGNORE --check-prefix=ASM
 //
-// Currently the stack size reporting cannot be checked with -verify because
-//  no source location is attached to the diagnostic. Therefore do not emit
-// them for the -verify test for now.
 // RUN: %clang_cc1 %s -S -o - -triple=i386-apple-darwin -verify -no-integrated-as
 
 extern void doIt(char *);
 
-// REGULAR: warning: stack size exceeded ({{[0-9]+}}) in stackSizeWarning
-// PROMOTE: error: stack size exceeded ({{[0-9]+}}) in stackSizeWarning
-// IGNORE-NOT: stack size exceeded ({{[0-9]+}}) in stackSizeWarning
+// REGULAR: warning: stack frame size of {{[0-9]+}} bytes in function 'stackSizeWarning'
+// PROMOTE: error: stack frame size of {{[0-9]+}} bytes in function 'stackSizeWarning'
+// IGNORE-NOT: stack frame size of {{[0-9]+}} bytes in function 'stackSizeWarning'
 void stackSizeWarning() {
   char buffer[80];
   doIt(buffer);