Make sure that any new and optimized objects created during GlobalOPT copy all the attributes from the base object.

Summary:
Make sure that any new and optimized objects created during GlobalOPT copy all the attributes from the base object.

A good example of improper behavior in the current implementation is section information associated with the GlobalObject. If a section was set for it, and GlobalOpt is creating/modifying a new object based on this one (often copying the original name), without this change new object will be placed in a default section, resulting in inappropriate properties of the new variable.
The argument here is that if customer specified a section for a variable, any changes to it that compiler does should not cause it to change that section allocation.
Moreover, any other properties worth representation in copyAttributesFrom() should also be propagated.

Reviewers: jmolloy, joker-eph, joker.eph

Subscribers: slarin, joker.eph, rafael, tobiasvk, llvm-commits

Differential Revision: http://reviews.llvm.org/D16074

llvm-svn: 258556

lib/Transforms/IPO/GlobalOpt.cpp

@@ -499,6 +499,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
                                                GV->getThreadLocalMode(),
                                               GV->getType()->getAddressSpace());
       NGV->setExternallyInitialized(GV->isExternallyInitialized());
+      NGV->copyAttributesFrom(GV);
       Globals.push_back(NGV);
       NewGlobals.push_back(NGV);
 
@@ -533,6 +534,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
                                                GV->getThreadLocalMode(),
                                               GV->getType()->getAddressSpace());
       NGV->setExternallyInitialized(GV->isExternallyInitialized());
+      NGV->copyAttributesFrom(GV);
       Globals.push_back(NGV);
       NewGlobals.push_back(NGV);
 
@@ -1291,6 +1293,7 @@ static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI,
         *GV->getParent(), PFieldTy, false, GlobalValue::InternalLinkage,
         Constant::getNullValue(PFieldTy), GV->getName() + ".f" + Twine(FieldNo),
         nullptr, GV->getThreadLocalMode());
+    NGV->copyAttributesFrom(GV);
     FieldGlobals.push_back(NGV);
 
     unsigned TypeSize = DL.getTypeAllocSize(FieldTy);
@@ -1610,6 +1613,7 @@ static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
                                              GV->getName()+".b",
                                              GV->getThreadLocalMode(),
                                              GV->getType()->getAddressSpace());
+  NewGV->copyAttributesFrom(GV);
   GV->getParent()->getGlobalList().insert(GV->getIterator(), NewGV);
 
   Constant *InitVal = GV->getInitializer();

test/Transforms/GlobalOpt/GSROA-section.ll

@@ -0,0 +1,30 @@
+; This test lets globalopt split the global struct and array into different
+; values. The pass needs to preserve section attribute.
+
+; RUN: opt < %s -globalopt -S | FileCheck %s
+; Check that the new global values still have their section assignment.
+; CHECK: @struct
+; CHECK: section ".foo"
+; CHECK: @array
+; CHECK-NOT: section ".foo"
+
+@struct = internal global { i32, i32 } zeroinitializer, section ".foo"
+@array = internal global [ 2 x i32 ] zeroinitializer
+
+define i32 @foo() {
+  %A = load i32, i32* getelementptr ({ i32, i32 }, { i32, i32 }* @struct, i32 0, i32 0)
+  %B = load i32, i32* getelementptr ([ 2 x i32 ], [ 2 x i32 ]* @array, i32 0, i32 0)
+  ; Use the loaded values, so they won't get removed completely
+  %R = add i32 %A, %B
+  ret i32 %R
+}
+
+; We put stores in a different function, so that the global variables won't get
+; optimized away completely.
+define void @bar(i32 %R) {
+  store i32 %R, i32* getelementptr ([ 2 x i32 ], [ 2 x i32 ]* @array, i32 0, i32 0)
+  store i32 %R, i32* getelementptr ({ i32, i32 }, { i32, i32 }* @struct, i32 0, i32 0)
+  ret void
+}
+
+

test/Transforms/GlobalOpt/MallocSROA-section.ll

@@ -0,0 +1,28 @@
+; RUN: opt -globalopt -S < %s | FileCheck %s
+; CHECK: @Y.f0
+; CHECK: section ".foo"
+; CHECK: @Y.f1
+; CHECK: section ".foo"
+
+%struct.xyz = type { double, i32 }
+
+@Y = internal global %struct.xyz* null ,section ".foo"            ; <%struct.xyz**> [#uses=2]
+@numf2s = external global i32                     ; <i32*> [#uses=1]
+
+define void @init_net()  {
+entry:
+  %0 = load i32, i32* @numf2s, align 4                 ; <i32> [#uses=1]
+  %mallocsize2 = shl i32 %0, 4                    ; <i32> [#uses=1]
+  %malloccall3 = tail call i8* @malloc(i32 %mallocsize2)  ; <i8*> [#uses=1]
+  %1 = bitcast i8* %malloccall3 to %struct.xyz*   ; <%struct.xyz*> [#uses=1]
+  store %struct.xyz* %1, %struct.xyz** @Y, align 8
+  ret void
+}
+
+define void @load_train()  {
+entry:
+  %0 = load %struct.xyz*, %struct.xyz** @Y, align 8             ; <%struct.xyz*> [#uses=0]
+  ret void
+}
+
+declare noalias i8* @malloc(i32)

test/Transforms/GlobalOpt/SROA-section.ll

@@ -0,0 +1,27 @@
+; Verify that section assignment is copied during SROA
+; RUN: opt < %s -globalopt -S | FileCheck %s
+; CHECK: @G.0
+; CHECK: section ".foo"
+; CHECK: @G.1
+; CHECK: section ".foo"
+; CHECK: @G.2
+; CHECK: section ".foo"
+
+%T = type { double, double, double }
+@G = internal global %T zeroinitializer, align 16, section ".foo"
+
+define void @test() {
+  store double 1.0, double* getelementptr (%T, %T* @G, i32 0, i32 0), align 16
+  store double 2.0, double* getelementptr (%T, %T* @G, i32 0, i32 1), align 8
+  store double 3.0, double* getelementptr (%T, %T* @G, i32 0, i32 2), align 16
+  ret void
+}
+
+define double @test2() {
+  %V1 = load double, double* getelementptr (%T, %T* @G, i32 0, i32 0), align 16
+  %V2 = load double, double* getelementptr (%T, %T* @G, i32 0, i32 1), align 8
+  %V3 = load double, double* getelementptr (%T, %T* @G, i32 0, i32 2), align 16
+  %R = fadd double %V1, %V2
+  %R2 = fadd double %R, %V3
+  ret double %R2
+}