AMDGPU/SI: Handle aliases in AMDGPUAlwaysInlinePass

[nhaustov]

Summary

Simply replace usage of aliases to functions with aliasee.
This came up when bitcode linking to builtin library and
calls to aliases not being resolved.

Also made minor improvements to existing test.

[arsenm]

LGTM. Can you also add a test which errors on an alias that is a constantexpr?

[nhaustov]

In D24023#529153, @arsenm wrote:

LGTM. Can you also add a test which errors on an alias that is a constantexpr?

Why would it error? It simply skips everything that is not alias to function.

lib/Target/AMDGPU/AMDGPUAlwaysInlinePass.cpp

public:
   const char *getPassName() const override { return "AMDGPU Always Inline Pass"; }
 };
 
 } // End anonymous namespace
 
 char AMDGPUAlwaysInline::ID = 0;
 
 bool AMDGPUAlwaysInline::runOnModule(Module &M) {
+  std::vector<GlobalAlias*> AliasesToRemove;
   std::vector<Function *> FuncsToClone;
 
+  for (GlobalAlias &A : M.aliases()) {
+    if (Function* F = dyn_cast<Function>(A.getAliasee())) {
+      A.replaceAllUsesWith(F);
+      AliasesToRemove.push_back(&A);
+    }
+  }
+
+  for (GlobalAlias* A : AliasesToRemove) {
+    A->eraseFromParent();
+  }
+
   for (Function &F : M) {
     if (!F.hasLocalLinkage() && !F.isDeclaration() && !F.use_empty() &&
         !F.hasFnAttribute(Attribute::NoInline))
       FuncsToClone.push_back(&F);
   }
 
   for (Function *F : FuncsToClone) {
     ValueToValueMapTy VMap;

test/CodeGen/AMDGPU/inline-calls.ll

 ; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s | FileCheck  %s
 ; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck  %s
 ; RUN: llc -march=r600 -mcpu=redwood -verify-machineinstrs < %s | FileCheck %s
 
 ; CHECK-NOT: {{^}}func:
 define internal fastcc i32 @func(i32 %a) {
 entry:
   %tmp0 = add i32 %a, 1
   ret i32 %tmp0
 }
 
 ; CHECK: {{^}}kernel:
+; CHECK-NOT: call
 define void @kernel(i32 addrspace(1)* %out) {
 entry:
   %tmp0 = call i32 @func(i32 1)
   store i32 %tmp0, i32 addrspace(1)* %out
   ret void
 }
 
 ; CHECK: {{^}}kernel2:
+; CHECK-NOT: call
 define void @kernel2(i32 addrspace(1)* %out) {
 entry:
   call void @kernel(i32 addrspace(1)* %out)
   ret void
 }
+
+; CHECK-NOT: func_alias
+@func_alias = alias i32 (i32), i32 (i32)* @func
+
+; CHECK: {{^}}kernel3:
+; CHECK-NOT: call
+define void @kernel3(i32 addrspace(1)* %out) {
+entry:
+  %tmp0 = call i32 @func_alias(i32 1)
+  store i32 %tmp0, i32 addrspace(1)* %out
+  ret void
+}
+
+; CHECK-NOT: kernel_alias
+@kernel_alias = alias void (i32 addrspace(1)*), void (i32 addrspace(1)*)* @kernel
+
+; CHECK: {{^}}kernel4:
+; CHECK-NOT: call
+define void @kernel4(i32 addrspace(1)* %out) {
+entry:
+  call void @kernel_alias(i32 addrspace(1)* %out)
+  ret void
+}