[PATCH] llvm.assume - CodeGen support

[hfinkel at anl.gov]

Hi chandlerc, reames,

This is part of the series started by D9375, and adds CodeGen support for llvm.noalias. The support is trivial (the intrinsic always returns its argument).

http://reviews.llvm.org/D9380

Files:
  lib/CodeGen/IntrinsicLowering.cpp
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  test/CodeGen/Generic/noalias.ll

Index: lib/CodeGen/IntrinsicLowering.cpp
===================================================================
--- lib/CodeGen/IntrinsicLowering.cpp
+++ lib/CodeGen/IntrinsicLowering.cpp
@@ -462,6 +462,11 @@
   case Intrinsic::assume:
   case Intrinsic::var_annotation:
     break;   // Strip out these intrinsics
+
+  case Intrinsic::noalias:
+    // Just forward the value
+    CI->replaceAllUsesWith(CI->getOperand(0));
+    break;
  
   case Intrinsic::memcpy: {
     Type *IntPtr = DL.getIntPtrType(Context);
Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4554,6 +4554,7 @@
   }
   case Intrinsic::annotation:
   case Intrinsic::ptr_annotation:
+  case Intrinsic::noalias:
     // Drop the intrinsic, but forward the value
     setValue(&I, getValue(I.getOperand(0)));
     return nullptr;
Index: test/CodeGen/Generic/noalias.ll
===================================================================
--- /dev/null
+++ test/CodeGen/Generic/noalias.ll
@@ -0,0 +1,12 @@
+; RUN: llc < %s
+
+define i8* @main(i8* %p) {
+  %v = call i8* @llvm.noalias.p0i8(i8* %p, metadata !1)
+  ret i8* %v
+}
+
+declare i8* @llvm.noalias.p0i8(i8*, metadata) nounwind
+
+!0 = !{!0, !"some domain"}
+!1 = !{!1, !0, !"some scope"}
+

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