Make the Preprocessor more memory efficient and improve macro instantiation diagnostics.

When a macro instantiation occurs, reserve a SLocEntry chunk with length the
full length of the macro definition source. Set the spelling location of this chunk
to point to the start of the macro definition and any tokens that are lexed directly
from the macro definition will get a location from this chunk with the appropriate offset.

For any tokens that come from argument expansion, '##' paste operator, etc. have their
instantiation location point at the appropriate place in the instantiated macro definition
(the argument identifier and the '##' token respectively).
This improves macro instantiation diagnostics:

Before:

t.c:5:9: error: invalid operands to binary expression ('struct S' and 'int')
int y = M(/);
        ^~~~
t.c:5:11: note: instantiated from:
int y = M(/);
          ^

After:

t.c:5:9: error: invalid operands to binary expression ('struct S' and 'int')
int y = M(/);
        ^~~~
t.c:3:20: note: instantiated from:
\#define M(op) (foo op 3);
                ~~~ ^  ~
t.c:5:11: note: instantiated from:
int y = M(/);
          ^

The memory savings for a candidate boost library that abuses the preprocessor are:

- 32% less SLocEntries (37M -> 25M)
- 30% reduction in PCH file size (900M -> 635M)
- 50% reduction in memory usage for the SLocEntry table (1.6G -> 800M)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134587 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/PCH/variables.c b/test/PCH/variables.c
index 58fd8ae..9f90b37 100644
--- a/test/PCH/variables.c
+++ b/test/PCH/variables.c
@@ -1,18 +1,40 @@
 // Test this without pch.
-// RUN: %clang_cc1 -include %S/variables.h -fsyntax-only -verify %s
+// RUN: %clang_cc1 -include %s -fsyntax-only -verify %s
 
 // Test with pch.
-// RUN: %clang_cc1 -emit-pch -o %t %S/variables.h
+// RUN: %clang_cc1 -emit-pch -o %t %s
 // RUN: %clang_cc1 -include-pch %t -fsyntax-only -verify %s 
 
+#ifndef HEADER
+#define HEADER
+
+extern float y;
+extern int *ip, x;
+
+float z; // expected-note{{previous}}
+
+int z2 = 17; // expected-note{{previous}}
+
+#define MAKE_HAPPY(X) X##Happy
+int MAKE_HAPPY(Very); // expected-note{{previous definition is here}}
+
+#define A_MACRO_IN_THE_PCH 492
+#define FUNCLIKE_MACRO(X, Y) X ## Y
+
+#define PASTE2(x,y) x##y
+#define PASTE1(x,y) PASTE2(x,y)
+#define UNIQUE(x) PASTE1(x,__COUNTER__)
+
+int UNIQUE(a);  // a0
+int UNIQUE(a);  // a1
+
+#else
+
 int *ip2 = &x;
 float *fp = &ip; // expected-warning{{incompatible pointer types}}
-// FIXME:variables.h expected-note{{previous}}
 double z; // expected-error{{redefinition}}
-// FIXME:variables.h expected-note{{previous}}
 int z2 = 18; // expected-error{{redefinition}}
 double VeryHappy; // expected-error{{redefinition}}
-// FIXME:variables.h expected-note{{previous definition is here}}
 
 int Q = A_MACRO_IN_THE_PCH;
 
@@ -21,3 +43,5 @@
 
 int UNIQUE(a);  // a2
 int *Arr[] = { &a0, &a1, &a2 };
+
+#endif