[llvm-commits] [llvm] r86840 - in /llvm/trunk: include/llvm/IntrinsicInst.h lib/Transforms/Utils/Local.cpp test/Transforms/InstCombine/invariant.ll

[Duncan Sands]

Author: baldrick
Date: Wed Nov 11 09:34:13 2009
New Revision: 86840

URL: http://llvm.org/viewvc/llvm-project?rev=86840&view=rev
Log:
Don't trivially delete unused calls to llvm.invariant.start.  This allows
llvm.invariant.start to be used without necessarily being paired with a call
to llvm.invariant.end.  If you run the entire optimization pipeline then such
calls are in fact deleted (adce does it), but that's actually a good thing since
we probably do want them to be zapped late in the game.  There should really be
an integration test that checks that the llvm.invariant.start call lasts long
enough that all passes that do interesting things with it get to do their stuff
before it is deleted.  But since no passes do anything interesting with it yet
this will have to wait for later.

Added:
    llvm/trunk/test/Transforms/InstCombine/invariant.ll
Modified:
    llvm/trunk/include/llvm/IntrinsicInst.h
    llvm/trunk/lib/Transforms/Utils/Local.cpp

Modified: llvm/trunk/include/llvm/IntrinsicInst.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IntrinsicInst.h?rev=86840&r1=86839&r2=86840&view=diff

==============================================================================
--- llvm/trunk/include/llvm/IntrinsicInst.h (original)
+++ llvm/trunk/include/llvm/IntrinsicInst.h Wed Nov 11 09:34:13 2009
@@ -320,6 +320,28 @@
     }
   };
   
+  /// MemoryUseIntrinsic - This is the common base class for the memory use
+  /// marker intrinsics.
+  ///
+  struct MemoryUseIntrinsic : public IntrinsicInst {
+
+    // Methods for support type inquiry through isa, cast, and dyn_cast:
+    static inline bool classof(const MemoryUseIntrinsic *) { return true; }
+    static inline bool classof(const IntrinsicInst *I) {
+      switch (I->getIntrinsicID()) {
+      case Intrinsic::lifetime_start:
+      case Intrinsic::lifetime_end:
+      case Intrinsic::invariant_start:
+      case Intrinsic::invariant_end:
+        return true;
+      default: return false;
+      }
+    }
+    static inline bool classof(const Value *V) {
+      return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
+    }
+  };
+
 }
 
 #endif

Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=86840&r1=86839&r2=86840&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Wed Nov 11 09:34:13 2009
@@ -252,6 +252,9 @@
   // We don't want debug info removed by anything this general.
   if (isa<DbgInfoIntrinsic>(I)) return false;
 
+  // Likewise for memory use markers.
+  if (isa<MemoryUseIntrinsic>(I)) return false;
+
   if (!I->mayHaveSideEffects()) return true;
 
   // Special case intrinsics that "may have side effects" but can be deleted

Added: llvm/trunk/test/Transforms/InstCombine/invariant.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/invariant.ll?rev=86840&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/invariant.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/invariant.ll Wed Nov 11 09:34:13 2009
@@ -0,0 +1,16 @@
+; Test to make sure unused llvm.invariant.start calls are not trivially eliminated
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+declare void @g(i8*)
+
+declare { }* @llvm.invariant.start(i64, i8* nocapture) nounwind readonly
+
+define i8 @f() {
+  %a = alloca i8                                  ; <i8*> [#uses=4]
+  store i8 0, i8* %a
+  %i = call { }* @llvm.invariant.start(i64 1, i8* %a) ; <{ }*> [#uses=0]
+  ; CHECK: call { }* @llvm.invariant.start
+  call void @g(i8* %a)
+  %r = load i8* %a                                ; <i8> [#uses=1]
+  ret i8 %r
+}