Do not put instrumentation counters before phis in ObjC for-in loops.

We still don't use the PGO to set branch weights for these loops, but at
least this keeps the compiler from crashing. <rdar://problem/16137778>

llvm-svn: 202002

clang/lib/CodeGen/CGObjC.cpp

@@ -1525,13 +1525,10 @@ void CodeGenFunction::EmitObjCForCollectionStmt(const ObjCForCollectionStmt &S){
   llvm::Value *initialMutations =
     Builder.CreateLoad(StateMutationsPtr, "forcoll.initial-mutations");
 
-  RegionCounter Cnt = getPGORegionCounter(&S);
-
   // Start looping.  This is the point we return to whenever we have a
   // fresh, non-empty batch of objects.
   llvm::BasicBlock *LoopBodyBB = createBasicBlock("forcoll.loopbody");
   EmitBlock(LoopBodyBB);
-  Cnt.beginRegion(Builder);
 
   // The current index into the buffer.
   llvm::PHINode *index = Builder.CreatePHI(UnsignedLongLTy, 3, "forcoll.index");
@@ -1541,6 +1538,9 @@ void CodeGenFunction::EmitObjCForCollectionStmt(const ObjCForCollectionStmt &S){
   llvm::PHINode *count = Builder.CreatePHI(UnsignedLongLTy, 3, "forcoll.count");
   count->addIncoming(initialBufferLimit, LoopInitBB);
 
+  RegionCounter Cnt = getPGORegionCounter(&S);
+  Cnt.beginRegion(Builder);
+
   // Check whether the mutations value has changed from where it was
   // at start.  StateMutationsPtr should actually be invariant between
   // refreshes.

clang/test/CodeGenObjC/Inputs/instr-profile.profdata

@@ -0,0 +1,7 @@
+foreach 2
+1
+2
+
+main 1
+1
+

clang/test/CodeGenObjC/instr-profile.m

@@ -0,0 +1,38 @@
+// Test that instrumentation based profiling feeds branch prediction
+// correctly. This tests both generation of profile data and use of the same,
+// and the input file for the -fprofile-instr-use case is expected to be result
+// of running the program generated by the -fprofile-instr-generate case. As
+// such, main() should call every function in this test.
+
+// RUN: %clang %s -o - -emit-llvm -S -fprofile-instr-generate | FileCheck -check-prefix=PGOGEN %s
+// RUN: %clang %s -o - -emit-llvm -S -fprofile-instr-use=%S/Inputs/instr-profile.profdata | FileCheck -check-prefix=PGOUSE %s
+
+#ifdef HAVE_FOUNDATION
+// Use this to build an instrumented version to regenerate the input file.
+#import <Foundation/Foundation.h>
+#else
+struct NSFastEnumerationState;
+@interface NSArray
+- (unsigned long) countByEnumeratingWithState: (struct NSFastEnumerationState*) state
+                  objects: (id*) buffer
+                  count: (unsigned long) bufferSize;
++(NSArray*) arrayWithObjects: (id) first, ...;
+@end;
+#endif
+
+// PGOGEN: @[[FOR:__llvm_pgo_ctr[0-9]*]] = private global [2 x i64] zeroinitializer
+
+// PGOGEN-LABEL: @foreach
+// PGOUSE-LABEL: @foreach
+// PGOGEN: store {{.*}} @[[FOR]], i64 0, i64 0
+void foreach(NSArray *array) {
+  // PGOGEN: store {{.*}} @[[FOR]], i64 0, i64 1
+  // FIXME: We don't emit branch weights for this yet.
+  for (id x in array) {
+  }
+}
+
+int main(int argc, const char *argv[]) {
+  NSArray *array = [NSArray arrayWithObjects: @"0", @"1", (void*)0];
+  foreach(array);
+}