[PowerPC][GlobalMerge] Enable GlobalMerge by default on AIX (#101226)

This patch turns on the GlobalMerge pass by default on AIX and updates
LIT tests accordingly.

Author: amy-kwan

llvm/lib/Target/PowerPC/PPCTargetMachine.cpp

@@ -500,7 +500,12 @@ void PPCPassConfig::addIRPasses() {
 }
 
 bool PPCPassConfig::addPreISel() {
-  if (EnableGlobalMerge)
+  // The GlobalMerge pass is intended to be on by default on AIX.
+  // Specifying the command line option overrides the AIX default.
+  if ((EnableGlobalMerge.getNumOccurrences() > 0)
+          ? EnableGlobalMerge
+          : (TM->getTargetTriple().isOSAIX() &&
+             getOptLevel() != CodeGenOptLevel::None))
     addPass(
         createGlobalMergePass(TM, GlobalMergeMaxOffset, false, false, true));
 

llvm/test/CodeGen/PowerPC/merge-private.ll

@@ -11,6 +11,12 @@
 ; RUN: llc -verify-machineinstrs -mtriple powerpc64-unknown-linux -mcpu=pwr8 \
 ; RUN:     -ppc-asm-full-reg-names -ppc-global-merge=true < %s | FileCheck %s \
 ; RUN:     --check-prefix=LINUX64BE
+; The below run line is added to ensure that the assembly corresponding to
+; the following check-prefix is generated by default on AIX (without any
+; options).
+; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr8 \
+; RUN:     -ppc-asm-full-reg-names < %s | FileCheck %s \
+; RUN:     --check-prefix=AIX64
 
 @.str = private unnamed_addr constant [15 x i8] c"Private global\00", align 1
 @str = internal constant [16 x i8] c"Internal global\00", align 1

llvm/test/CodeGen/PowerPC/mergeable-string-pool.ll

@@ -1,6 +1,6 @@
-; RUN: llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr8 \
+; RUN: llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr8 -enable-global-merge=false \
 ; RUN:   -ppc-asm-full-reg-names < %s | FileCheck %s --check-prefixes=AIX32,AIXDATA
-; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr8 \
+; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr8 -enable-global-merge=false \
 ; RUN:   -ppc-asm-full-reg-names < %s | FileCheck %s --check-prefixes=AIX64,AIXDATA
 ; RUN: llc -verify-machineinstrs -mtriple powerpc64-unknown-linux -mcpu=pwr8 \
 ; RUN:   -ppc-asm-full-reg-names < %s | FileCheck %s --check-prefixes=LINUX64BE,LINUXDATA

llvm/test/DebugInfo/Symbolize/XCOFF/xcoff-symbolize-data.ll

@@ -5,7 +5,7 @@
 ;; AIX assembly syntax.
 
 ; REQUIRES: powerpc-registered-target
-; RUN: llc -filetype=obj -o %t -mtriple=powerpc-aix-ibm-xcoff < %s
+; RUN: llc -filetype=obj -o %t -mtriple=powerpc-aix-ibm-xcoff -ppc-global-merge=false < %s
 ; RUN: llvm-symbolizer --obj=%t 'DATA 0x60' 'DATA 0x61' 'DATA 0x64' 'DATA 0X68' \
 ; RUN:   'DATA 0x90' 'DATA 0x94' 'DATA 0X98' | \
 ; RUN:   FileCheck %s