[XCOFF][DWARF] set default DWARF version to 3.

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D98010

Author: Chen Zheng

clang/lib/Driver/ToolChains/AIX.h

@@ -74,6 +74,9 @@ class LLVM_LIBRARY_VISIBILITY AIX : public ToolChain {
 
   RuntimeLibType GetDefaultRuntimeLibType() const override;
 
+  // Set default DWARF version to 3 for now as latest AIX OS supports version 3.
+  unsigned GetDefaultDwarfVersion() const override { return 3; }
+
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;

clang/test/CodeGen/dwarf-version.c

@@ -32,6 +32,17 @@
 //     Explicitly request both.
 // RUN: %clang -target i686-pc-windows-msvc -gdwarf -gcodeview -S -emit-llvm -o - %s \
 // RUN:     | FileCheck %s --check-prefixes=VER4,CODEVIEW
+// RUN: %clang -target powerpc-ibm-aix-xcoff -g -S -emit-llvm -o - %s | \
+// RUN:   FileCheck %s --check-prefix=VER3
+// RUN: %clang -target powerpc-ibm-aix-xcoff -gdwarf-2 -S -emit-llvm -o - %s | \
+// RUN:   FileCheck %s --check-prefix=VER2
+// RUN: %clang -target powerpc-ibm-aix-xcoff -gdwarf-3 -S -emit-llvm -o - %s | \
+// RUN:   FileCheck %s --check-prefix=VER3
+// RUN: %clang -target powerpc-ibm-aix-xcoff -gdwarf-4 -S -emit-llvm -o - %s | \
+// RUN:   FileCheck %s --check-prefix=VER4
+// RUN: %clang -target powerpc-ibm-aix-xcoff -gdwarf-5 -S -emit-llvm -o - %s | \
+// RUN:   FileCheck %s --check-prefix=VER5
+
 int main (void) {
   return 0;
 }