Allow targets to opt-in to codegen in SCC order

Decouple this setting from EnableIRPA.

To support function calls on AMDGPU, it is necessary to
report the global register usage throughout the kernel's
call graph, so callees need to be handled first.

llvm-svn: 299487

2 files changed, 15 insertions, 2 deletions

diff --git a/llvm/include/llvm/CodeGen/TargetPassConfig.h b/llvm/include/llvm/CodeGen/TargetPassConfig.h
index 2156e87872f..f0c826dc1d4 100644
--- a/llvm/include/llvm/CodeGen/TargetPassConfig.h
+++ b/llvm/include/llvm/CodeGen/TargetPassConfig.h
@@ -115,6 +115,10 @@ protected:
   /// Default setting for -enable-tail-merge on this target.
   bool EnableTailMerge;
 
+  /// Require processing of functions such that callees are generated before
+  /// callers.
+  bool RequireCodeGenSCCOrder;
+
 public:
   TargetPassConfig(TargetMachine *tm, PassManagerBase &pm);
   // Dummy constructor.
@@ -162,6 +166,11 @@ public:
   bool getEnableTailMerge() const { return EnableTailMerge; }
   void setEnableTailMerge(bool Enable) { setOpt(EnableTailMerge, Enable); }
 
+  bool requiresCodeGenSCCOrder() const { return RequireCodeGenSCCOrder; }
+  void setRequiresCodeGenSCCOrder(bool Enable = true) {
+    setOpt(RequireCodeGenSCCOrder, Enable);
+  }
+
   /// Allow the target to override a specific pass without overriding the pass
   /// pipeline. When passes are added to the standard pipeline at the
   /// point where StandardID is expected, add TargetID in its place.
diff --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
index 09ca1de21a8..150195f5f85 100644
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -264,7 +264,8 @@ TargetPassConfig::~TargetPassConfig() {
 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
     : ImmutablePass(ID), PM(&pm), Started(true), Stopped(false),
       AddingMachinePasses(false), TM(tm), Impl(nullptr), Initialized(false),
-      DisableVerify(false), EnableTailMerge(true) {
+      DisableVerify(false), EnableTailMerge(true),
+      RequireCodeGenSCCOrder(false) {
 
   Impl = new PassConfigImpl();
 
@@ -282,6 +283,9 @@ TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
 
   if (StringRef(PrintMachineInstrs.getValue()).equals(""))
     TM->Options.PrintMachineCode = true;
+
+  if (TM->Options.EnableIPRA)
+    setRequiresCodeGenSCCOrder();
 }
 
 CodeGenOpt::Level TargetPassConfig::getOptLevel() const {
@@ -534,7 +538,7 @@ void TargetPassConfig::addISelPrepare() {
   addPreISel();
 
   // Force codegen to run according to the callgraph.
-  if (TM->Options.EnableIPRA)
+  if (requiresCodeGenSCCOrder())
     addPass(new DummyCGSCCPass);
 
   // Add both the safe stack and the stack protection passes: each of them will