Change all ARM calls into indirect calls.

src/IceTargetLoweringARM32.cpp

Index: src/IceTargetLoweringARM32.cpp
diff --git a/src/IceTargetLoweringARM32.cpp b/src/IceTargetLoweringARM32.cpp
index 0322a7e54ef60c6a77ff3599f78f52998d4a1620..4139fb8b951b9bc6b3bb581e24f1930367f7d3c7 100644
--- a/src/IceTargetLoweringARM32.cpp
+++ b/src/IceTargetLoweringARM32.cpp
@@ -3349,7 +3349,10 @@ void TargetARM32::lowerBr(const InstBr *Instr) {
 }
 
 void TargetARM32::lowerCall(const InstCall *Instr) {
-  Operand *CallTarget = Instr->getCallTarget();
+  // Note: Keep original call target. This allows us to call the correct
+  // postamble helper, even if the CallTarget gets modified during lowering.
+  Operand *OrigCallTarget = Instr->getCallTarget();
+  Operand *CallTarget = OrigCallTarget;
   if (Instr->isTargetHelperCall()) {
     auto TargetHelperPreamble = ARM32HelpersPreamble.find(CallTarget);
     if (TargetHelperPreamble != ARM32HelpersPreamble.end()) {
@@ -3474,12 +3477,9 @@ void TargetARM32::lowerCall(const InstCall *Instr) {
     }
   }
 
-  // Allow ConstantRelocatable to be left alone as a direct call, but force
-  // other constants like ConstantInteger32 to be in a register and make it an
-  // indirect call.
-  if (!llvm::isa<ConstantRelocatable>(CallTarget)) {
-    CallTarget = legalize(CallTarget, Legal_Reg);
-  }
+  // Note: To allow far calls, even for constant relocatables, we force
+  // the call target into a register, and make an indirect call.
+  CallTarget = legalizeToReg(CallTarget);
 
   // Copy arguments to be passed in registers to the appropriate registers.
   for (auto &FPArg : FPArgs) {
@@ -3530,7 +3530,7 @@ void TargetARM32::lowerCall(const InstCall *Instr) {
   }
 
   if (Instr->isTargetHelperCall()) {
-    auto TargetHelpersPostamble = ARM32HelpersPostamble.find(CallTarget);
+    auto TargetHelpersPostamble = ARM32HelpersPostamble.find(OrigCallTarget);
     if (TargetHelpersPostamble != ARM32HelpersPostamble.end()) {
       (this->*TargetHelpersPostamble->second)(Instr);
     }