[llvm] r232435 - LowerBitSets: do not use private aliases at all on Darwin.

[Peter Collingbourne]

Author: pcc
Date: Mon Mar 16 18:36:24 2015
New Revision: 232435

URL: http://llvm.org/viewvc/llvm-project?rev=232435&view=rev
Log:
LowerBitSets: do not use private aliases at all on Darwin.

LLVM currently turns these into linker-private symbols, which can be dead
stripped by the Darwin linker.

Modified:
    llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp
    llvm/trunk/test/Transforms/LowerBitSets/simple.ll

Modified: llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp?rev=232435&r1=232434&r2=232435&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/LowerBitSets.cpp Mon Mar 16 18:36:24 2015
@@ -349,9 +349,13 @@ void LowerBitSets::allocateByteArrays()
     // Create an alias instead of RAUW'ing the gep directly. On x86 this ensures
     // that the pc-relative displacement is folded into the lea instead of the
     // test instruction getting another displacement.
-    GlobalAlias *Alias = GlobalAlias::create(
-        Int8Ty, 0, GlobalValue::PrivateLinkage, "bits", GEP, M);
-    BAI->ByteArray->replaceAllUsesWith(Alias);
+    if (LinkerSubsectionsViaSymbols) {
+      BAI->ByteArray->replaceAllUsesWith(GEP);
+    } else {
+      GlobalAlias *Alias = GlobalAlias::create(
+          Int8Ty, 0, GlobalValue::PrivateLinkage, "bits", GEP, M);
+      BAI->ByteArray->replaceAllUsesWith(Alias);
+    }
     BAI->ByteArray->eraseFromParent();
   }
 
@@ -529,15 +533,16 @@ void LowerBitSets::buildBitSetsFromGloba
                                       ConstantInt::get(Int32Ty, I * 2)};
     Constant *CombinedGlobalElemPtr =
         ConstantExpr::getGetElementPtr(CombinedGlobal, CombinedGlobalIdxs);
-    GlobalValue::LinkageTypes GAliasLinkage = LinkerSubsectionsViaSymbols
-                                                  ? GlobalValue::PrivateLinkage
-                                                  : Globals[I]->getLinkage();
-    GlobalAlias *GAlias = GlobalAlias::create(
-        Globals[I]->getType()->getElementType(),
-        Globals[I]->getType()->getAddressSpace(), GAliasLinkage,
-        "", CombinedGlobalElemPtr, M);
-    GAlias->takeName(Globals[I]);
-    Globals[I]->replaceAllUsesWith(GAlias);
+    if (LinkerSubsectionsViaSymbols) {
+      Globals[I]->replaceAllUsesWith(CombinedGlobalElemPtr);
+    } else {
+      GlobalAlias *GAlias = GlobalAlias::create(
+          Globals[I]->getType()->getElementType(),
+          Globals[I]->getType()->getAddressSpace(), Globals[I]->getLinkage(),
+          "", CombinedGlobalElemPtr, M);
+      GAlias->takeName(Globals[I]);
+      Globals[I]->replaceAllUsesWith(GAlias);
+    }
     Globals[I]->eraseFromParent();
   }
 }

Modified: llvm/trunk/test/Transforms/LowerBitSets/simple.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LowerBitSets/simple.ll?rev=232435&r1=232434&r2=232435&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LowerBitSets/simple.ll (original)
+++ llvm/trunk/test/Transforms/LowerBitSets/simple.ll Mon Mar 16 18:36:24 2015
@@ -42,10 +42,20 @@ target datalayout = "e-p:32:32"
 ; CHECK: @b = alias getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 2)
 ; CHECK: @c = alias getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 4)
 ; CHECK: @d = alias getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 6)
-; CHECK-DARWIN: @a = private alias
-; CHECK-DARWIN: @b = private alias
-; CHECK-DARWIN: @c = private alias
-; CHECK-DARWIN: @d = private alias
+
+; CHECK-DARWIN: @aptr = constant i32* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G:@[^ ]*]], i32 0, i32 0)
+ at aptr = constant i32* @a
+
+; CHECK-DARWIN: @bptr = constant [63 x i32]* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 2)
+ at bptr = constant [63 x i32]* @b
+
+; CHECK-DARWIN: @cptr = constant i32* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 4)
+ at cptr = constant i32* @c
+
+; CHECK-DARWIN: @dptr = constant [2 x i32]* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 6)
+ at dptr = constant [2 x i32]* @d
+
+; CHECK-DARWIN: [[G]] = private constant
 
 ; CHECK: @bits = private alias getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)
 ; CHECK: @bits1 = private alias getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)