[flang][AIX] Predefine __64BIT__ and _AIX macros (#138591)

flang/lib/Frontend/CompilerInvocation.cpp

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 28f2f69..238079a 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -1615,13 +1615,10 @@
   }
 
   llvm::Triple targetTriple{llvm::Triple(this->targetOpts.triple)};
-  if (targetTriple.isPPC()) {
-    // '__powerpc__' is a generic macro for any PowerPC cases. e.g. Max integer
-    // size.
-    fortranOptions.predefinitions.emplace_back("__powerpc__", "1");
-  }
   if (targetTriple.isOSLinux()) {
     fortranOptions.predefinitions.emplace_back("__linux__", "1");
+  } else if (targetTriple.isOSAIX()) {
+    fortranOptions.predefinitions.emplace_back("_AIX", "1");
   }
 
   switch (targetTriple.getArch()) {
@@ -1631,6 +1628,16 @@
     fortranOptions.predefinitions.emplace_back("__x86_64__", "1");
     fortranOptions.predefinitions.emplace_back("__x86_64", "1");
     break;
+  case llvm::Triple::ArchType::ppc:
+  case llvm::Triple::ArchType::ppc64:
+  case llvm::Triple::ArchType::ppcle:
+  case llvm::Triple::ArchType::ppc64le:
+    // '__powerpc__' is a generic macro for any PowerPC.
+    fortranOptions.predefinitions.emplace_back("__powerpc__", "1");
+    if (targetTriple.isOSAIX() && targetTriple.isArch64Bit()) {
+      fortranOptions.predefinitions.emplace_back("__64BIT__", "1");
+    }
+    break;
   }
 }
 

flang/test/Driver/predefined-macros-powerpc2.f90

diff --git a/flang/test/Driver/predefined-macros-powerpc2.f90 b/flang/test/Driver/predefined-macros-powerpc2.f90
index 6e10235..6d235af 100644
--- a/flang/test/Driver/predefined-macros-powerpc2.f90
+++ b/flang/test/Driver/predefined-macros-powerpc2.f90
@@ -1,13 +1,25 @@
 ! Test predefined macro for PowerPC architecture
 
-! RUN: %flang_fc1 -triple ppc64le-unknown-linux -cpp -E %s | FileCheck %s
+! RUN: %flang_fc1 -triple ppc64le-unknown-linux -cpp -E %s | FileCheck %s -check-prefix=CHECK-LINUX
+! RUN: %flang_fc1 -triple powerpc-unknown-aix -cpp -E %s | FileCheck %s -check-prefix=CHECK-AIX32
+! RUN: %flang_fc1 -triple powerpc64-unknown-aix -cpp -E %s | FileCheck %s -check-prefix=CHECK-AIX64
 ! REQUIRES: target=powerpc{{.*}}
 
-! CHECK: integer :: var1 = 1
-! CHECK: integer :: var2 = 1
+! CHECK-LINUX: integer :: var1 = 1
+! CHECK-LINUX: integer :: var2 = 1
+! CHECK-AIX32: integer :: var1 = 1
+! CHECK-AIX32: integer :: var2 = 1
+! CHECK-AIX32: integer :: var3 = __64BIT__
+! CHECK-AIX64: integer :: var1 = 1
+! CHECK-AIX64: integer :: var2 = 1
+! CHECK-AIX64: integer :: var3 = 1
 
 #if defined(__linux__) && defined(__powerpc__)
   integer :: var1 = __powerpc__
   integer :: var2 = __linux__
+#elif defined(_AIX) && defined(__powerpc__)
+  integer :: var1 = __powerpc__
+  integer :: var2 = _AIX
+  integer :: var3 = __64BIT__
 #endif
 end program