[cfe-dev] Big slowdown introduced in r92348

[Abramo Bagnara]

Using as usual the big gcc.c source from

http://people.csail.mit.edu/smcc/projects/single-file-programs/

$ time ~/llvm_opt/Release/bin/clang -w -fsyntax-only gcc.c

real	0m3.792s
user	0m3.472s
sys	0m0.319s
$ time ~/llvm_opt/Release/bin/clang -w -fsyntax-only gcc.c

real	0m13.384s
user	0m13.046s
sys	0m0.335s

Using bisection I've found the culprit in commit r92348.

Why a modify to Sema::LookupTemplateName could impact a non C++ program
is beyond my comprehension, but perhaps the name of function is
misleading I don't know...