Implement -finstrument-functions.

Closes #1839.

driver/cl_options.cpp

@@ -455,6 +455,11 @@ cl::opt<std::string> usefileInstrProf(
     cl::ValueRequired);
 #endif
 
+cl::opt<bool>
+    instrumentFunctions("finstrument-functions",
+                        cl::desc("Instrument function entry and exit with "
+                                 "GCC-compatible profiling calls"));
+
 static cl::extrahelp footer(
     "\n"
     "-d-debug can also be specified without options, in which case it enables "

driver/cl_options.h

@@ -87,6 +87,7 @@ extern cl::opt<unsigned, true> nestedTemplateDepth;
 extern cl::opt<std::string> genfileInstrProf;
 extern cl::opt<std::string> usefileInstrProf;
 #endif
+extern cl::opt<bool> instrumentFunctions;
 
 // Arguments to -d-debug
 extern std::vector<std::string> debugArgs;

gen/functions.cpp

@@ -973,6 +973,9 @@ void DtoDefineFunction(FuncDeclaration *fd, bool linkageAvailableExternally) {
   // debug info - after all allocas, but before any llvm.dbg.declare etc
   gIR->DBuilder.EmitFuncStart(fd);
 
+  if (opts::instrumentFunctions && fd->emitInstrumentation)
+    emitInstrumentationFn(false);
+
   // this hack makes sure the frame pointer elimination optimization is
   // disabled.
   // this this eliminates a bunch of inline asm related issues.
@@ -1088,6 +1091,9 @@ void DtoDefineFunction(FuncDeclaration *fd, bool linkageAvailableExternally) {
     // llvm requires all basic blocks to end with a TerminatorInst but DMD does
     // not put a return statement in automatically, so we do it here.
 
+    if (opts::instrumentFunctions && fd->emitInstrumentation)
+      emitInstrumentationFn(true);
+
     // pass the previous block into this block
     gIR->DBuilder.EmitStopPoint(fd->endloc);
     if (func->getReturnType() == LLType::getVoidTy(gIR->context())) {

gen/runtime.cpp

@@ -221,7 +221,8 @@ static void createFwdDecl(LINK linkage, Type *returntype,
                           ArrayParam<llvm::StringRef> fnames,
                           ArrayParam<Type *> paramtypes,
                           ArrayParam<StorageClass> paramsSTC = {},
-                          AttrSet attribset = AttrSet()) {
+                          AttrSet attribset = AttrSet(),
+                          llvm::Module *module = M) {
 
   Parameters *params = nullptr;
   if (!paramtypes.empty()) {
@@ -244,7 +245,7 @@ static void createFwdDecl(LINK linkage, Type *returntype,
 
   for (auto fname : fnames) {
     llvm::Function *fn = llvm::Function::Create(
-        llfunctype, llvm::GlobalValue::ExternalLinkage, fname, M);
+        llfunctype, llvm::GlobalValue::ExternalLinkage, fname, module);
 
     fn->setAttributes(attrs);
 
@@ -327,6 +328,16 @@ static void buildRuntimeModule() {
   //////////////////////////////////////////////////////////////////////////////
   //////////////////////////////////////////////////////////////////////////////
 
+  // void __cyg_profile_func_enter(void *callee, void *caller)
+  // void __cyg_profile_func_exit(void *callee, void *caller)
+  createFwdDecl(LINKc, voidTy,
+                {"__cyg_profile_func_exit", "__cyg_profile_func_enter"},
+                {voidPtrTy, voidPtrTy});
+
+  //////////////////////////////////////////////////////////////////////////////
+  //////////////////////////////////////////////////////////////////////////////
+  //////////////////////////////////////////////////////////////////////////////
+
   // void _d_assert(string file, uint line)
   // void _d_arraybounds(string file, uint line)
   createFwdDecl(LINKc, Type::tvoid, {"_d_assert", "_d_arraybounds"},
@@ -736,3 +747,20 @@ static void buildRuntimeModule() {
     }
   }
 }
+
+void emitInstrumentationFn(bool atExit) {
+  const char *name =
+      atExit ? "__cyg_profile_func_exit" : "__cyg_profile_func_enter";
+  LLFunction *fn = getRuntimeFunction(Loc(), gIR->module, name);
+
+  // Grab the address of the calling function
+  auto *caller =
+      gIR->ir->CreateCall(GET_INTRINSIC_DECL(returnaddress), DtoConstInt(1));
+  auto callee = DtoBitCast(gIR->topfunc(), getVoidPtrType());
+
+#if LDC_LLVM_VER >= 307
+  gIR->ir->CreateCall(fn, {callee, caller});
+#else
+  gIR->ir->CreateCall2(fn, callee, caller);
+#endif
+}

gen/runtime.h

@@ -32,4 +32,6 @@ llvm::Function *getRuntimeFunction(const Loc &loc, llvm::Module &target,
 llvm::GlobalVariable *
 getRuntimeGlobal(const Loc &loc, llvm::Module &target, const char *name);
 
+void emitInstrumentationFn(bool atExit);
+
 #endif // LDC_GEN_RUNTIME_H

gen/statements.cpp

@@ -12,6 +12,7 @@
 #include "module.h"
 #include "mtype.h"
 #include "port.h"
+#include "driver/cl_options.h"
 #include "gen/abi.h"
 #include "gen/arrays.h"
 #include "gen/classes.h"
@@ -134,6 +135,9 @@ class ToIRVisitor : public Visitor {
     FuncDeclaration *const fd = f->decl;
     LLFunction *const llFunc = f->func;
 
+    if (opts::instrumentFunctions && fd->emitInstrumentation)
+      emitInstrumentationFn(true);
+
     // is there a return value expression?
     if (stmt->exp || (!stmt->exp && (llFunc == irs->mainFunc))) {
       // if the function's return type is void, it uses sret

tests/codegen/instrumentation.d

@@ -0,0 +1,29 @@
+// RUN: %ldc -c -output-ll -finstrument-functions -of=%t.ll %s && FileCheck %s < %t.ll
+
+void fun0 () {
+  // CHECK-LABEL: define{{.*}} @{{.*}}4fun0FZv
+  // CHECK: call void @__cyg_profile_func_enter
+  // CHECK: call void @__cyg_profile_func_exit
+  // CHECK-NEXT: ret
+  return;
+}
+
+pragma(LDC_profile_instr, false)
+int fun1 (int x) {
+  // CHECK-LABEL: define{{.*}} @{{.*}}4fun1FiZi
+  // CHECK-NOT: call void @__cyg_profile_func_enter
+  // CHECK-NOT: call void @__cyg_profile_func_exit
+  return 42;
+}
+
+bool fun2 (int x) {
+  // CHECK-LABEL: define{{.*}} @{{.*}}4fun2FiZb
+  if (x < 10)
+    // CHECK: call void @__cyg_profile_func_exit
+    // CHECK-NEXT: ret
+    return true;
+
+  // CHECK: call void @__cyg_profile_func_exit
+  // CHECK-NEXT: ret
+  return false;
+}