[AIX] Fix mcount name and call arguments

[francii]

Summary

Currently, compiling a program with the -pg flag will result in an undefined symbol error for .mcount. This revision fixes the call to use __mcount, which requires a pointer argument to a pointer-sized object (unique per inserted call) on AIX.

This is only a partial fix. This patch should fix the -pg flag's behaviour on AIX to work with code you are compiling, but it will not link against standard libraries with mcount instrumentation calls. The next step is to add profiled libraries to the linker search paths in the Clang driver for the AIX toolchain when linking with -pg.

[cebowleratibm]

clang/test/CodeGen/mcount-aix.c

3

Is it necessary to specify -no-opaque-pointers for this test?

[cebowleratibm]

clang/lib/Basic/Targets/OSTargets.h

754 ↗

(On Diff #465808)

Suggest sticking with the normal mcount name and remapping on the call insertion when the target is AIX.

[francii]

Removed use of -no-opaque-pointers and call to "__mcount.aix"

[francii]

Removed __mcount.aix usage

[francii]

Replace target pointers with opaque pointers

[cebowleratibm]

llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp

40

Please use isOSAIX

[francii]

Updated target triple check to use isOSAIX()

[hubert.reinterpretcast]

llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp

39–40

A Twine can be implicitly constructed from a std::string. The implicit conversion works in this context.
Also: Change the variable name to use the LLVM naming convention for non-"functions".

41

I see no reason why we should assume that all of the other function names should have the extra argument passed on AIX.

[francii]

"Added check for __mcount on aix

[hubert.reinterpretcast]

LGTM with minor comment; thanks!

llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp

40

The construction for the Triple already did the string processing.

[francii]

Updated check for Func name

[cebowleratibm]

I had a typo in the commit so this didn't auto close.

clang/test/CodeGen/mcount-aix.c

+// RUN: %clang_cc1 -pg -triple powerpc-ibm-aix7.2.0.0 -S -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -pg -triple powerpc64-ibm-aix7.2.0.0 -S -emit-llvm %s -o - | FileCheck %s -check-prefix=CHECK64
+
+void foo() {
+}
+
+void bar() {
+    foo();
+}
+// CHECK: @[[GLOB0:[0-9]+]] = internal global i32 0
+// CHECK: @[[GLOB1:[0-9]+]] = internal global i32 0
+// CHECK64: @[[GLOB0:[0-9]+]] = internal global i64 0
+// CHECK64: @[[GLOB1:[0-9]+]] = internal global i64 0
+// CHECK-LABEL: @foo(
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    call void @__mcount(i32* @[[GLOB0]])
+// CHECK64-LABEL: @foo(
+// CHECK64-NEXT:  entry:
+// CHECK64-NEXT:    call void @__mcount(i64* @[[GLOB0]])
+// CHECK-LABEL: @bar(
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    call void @__mcount(i32* @[[GLOB1]])
+// CHECK64-LABEL: @bar(
+// CHECK64-NEXT:  entry:
+// CHECK64-NEXT:    call void @__mcount(i64* @[[GLOB1]])

llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp

 //===- EntryExitInstrumenter.cpp - Function Entry/Exit Instrumentation ----===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
if (Func == "mcount" ||
       Func == "llvm.arm.gnu.eabi.mcount" ||
       Func == "\01_mcount" ||
       Func == "\01mcount" ||
       Func == "__mcount" ||
       Func == "_mcount" ||
       Func == "__cyg_profile_func_enter_bare") {
     FunctionCallee Fn = M.getOrInsertFunction(Func, Type::getVoidTy(C));
     CallInst *Call = CallInst::Create(Fn, "", InsertionPt);
     Call->setDebugLoc(DL);
     return;
   }
 
+  if (Func == "__mcount.aix") {
+    Type *SizeTy = M.getDataLayout().getIntPtrType(C);
+    Type *SizePtrTy = SizeTy->getPointerTo();
+    GlobalVariable *GV = new GlobalVariable(M, SizeTy, /*isConstant=*/false,
+                                            GlobalValue::InternalLinkage,
+                                            ConstantInt::get(SizeTy, 0));
+    CallInst *Call = CallInst::Create(
+        M.getOrInsertFunction("__mcount",
+                              FunctionType::get(Type::getVoidTy(C), {SizePtrTy},
+                                                /*isVarArg=*/false)),
+        {GV}, "", InsertionPt);
+    Call->setDebugLoc(DL);
+    return;
+  }
+
   if (Func == "__cyg_profile_func_enter" || Func == "__cyg_profile_func_exit") {
     Type *ArgTypes[] = {Type::getInt8PtrTy(C), Type::getInt8PtrTy(C)};
 
     FunctionCallee Fn = M.getOrInsertFunction(
         Func, FunctionType::get(Type::getVoidTy(C), ArgTypes, false));
 
     Instruction *RetAddr = CallInst::Create(
         Intrinsic::getDeclaration(&M, Intrinsic::returnaddress),