If a global constant is dead then global's debug info should not prevent the optimize...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65994 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 0a35fa93e43ee4f9558ec673331863ee2dae7684..28cd902472dcf3f70ffdbee3d5eea038cc01fabe 100644 (file)
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -137,15 +137,23 @@ struct VISIBILITY_HIDDEN GlobalStatus {
 }
 
 /// ConstantIsDead - Return true if the specified constant is (transitively)
-/// dead.  The constant may be used by other constants (e.g. constant arrays and
-/// constant exprs) as long as they are dead, but it cannot be used by anything
-/// else.
-static bool ConstantIsDead(Constant *C) {
+/// dead.  The constant may be used by other constants (e.g. constant arrays,
+/// constant exprs, constant global variables) as long as they are dead, 
+/// but it cannot be used by anything else. If DeadGVs is not null then
+/// record dead constant GV users.
+static bool ConstantIsDead(Constant *C, 
+                           SmallPtrSet<GlobalVariable *, 4> *DeadGVs = false) {
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C))
+    if (GV->hasLocalLinkage() && GV->use_empty()) {
+      if (DeadGVs)
+        DeadGVs->insert(GV);
+      return true;
+    }
   if (isa<GlobalValue>(C)) return false;
 
   for (Value::use_iterator UI = C->use_begin(), E = C->use_end(); UI != E; ++UI)
     if (Constant *CU = dyn_cast<Constant>(*UI)) {
-      if (!ConstantIsDead(CU)) return false;
+      if (!ConstantIsDead(CU, DeadGVs)) return false;
     } else
       return false;
   return true;
@@ -338,7 +346,13 @@ static bool CleanupConstantGlobalUsers(Value *V, Constant *Init) {
     } else if (Constant *C = dyn_cast<Constant>(U)) {
       // If we have a chain of dead constantexprs or other things dangling from
       // us, and if they are all dead, nuke them without remorse.
-      if (ConstantIsDead(C)) {
+      SmallPtrSet<GlobalVariable *, 4> DeadGVs;
+      if (ConstantIsDead(C, &DeadGVs)) {
+        for (SmallPtrSet<GlobalVariable *, 4>::iterator TI = DeadGVs.begin(),
+               TE = DeadGVs.end(); TI != TE; ) {
+          GlobalVariable *TGV = *TI; ++TI;
+          TGV->eraseFromParent();
+        }
         C->destroyConstant();
         // This could have invalidated UI, start over from scratch.
         CleanupConstantGlobalUsers(V, Init);

diff --git a/test/Transforms/GlobalOpt/2009-03-03-dbg.ll b/test/Transforms/GlobalOpt/2009-03-03-dbg.ll
new file mode 100644 (file)
index 0000000..aa0bd0a
--- /dev/null
+++ b/test/Transforms/GlobalOpt/2009-03-03-dbg.ll
@@ -0,0 +1,52 @@
+; RUN: llvm-as < %s | opt -globalopt | llvm-dis | not grep global_variable42
+       %llvm.dbg.anchor.type = type { i32, i32 }
+       %llvm.dbg.basictype.type = type { i32, { }*, i8*, { }*, i32, i64, i64, i64, i32, i32 }
+       %llvm.dbg.compile_unit.type = type { i32, { }*, i32, i8*, i8*, i8*, i1, i1, i8*, i32 }
+       %llvm.dbg.composite.type = type { i32, { }*, i8*, { }*, i32, i64, i64, i64, i32, { }*, { }*, i32 }
+       %llvm.dbg.derivedtype.type = type { i32, { }*, i8*, { }*, i32, i64, i64, i64, i32, { }* }
+       %llvm.dbg.global_variable.type = type { i32, { }*, { }*, i8*, i8*, i8*, { }*, i32, { }*, i1, i1, { }* }
+       %llvm.dbg.subprogram.type = type { i32, { }*, { }*, i8*, i8*, i8*, { }*, i32, { }*, i1, i1 }
+       %llvm.dbg.subrange.type = type { i32, i64, i64 }
+       %llvm.dbg.variable.type = type { i32, { }*, i8*, { }*, i32, { }* }
+@llvm.dbg.compile_units = linkonce constant %llvm.dbg.anchor.type { i32 458752, i32 17 }, section "llvm.metadata"              ; <%llvm.dbg.anchor.type*> [#uses=1]
+@.str = internal constant [4 x i8] c"a.c\00", section "llvm.metadata"          ; <[4 x i8]*> [#uses=1]
+@.str1 = internal constant [5 x i8] c"/tmp\00", section "llvm.metadata"                ; <[5 x i8]*> [#uses=1]
+@.str2 = internal constant [57 x i8] c"4.2.1 (Based on Apple Inc. build 5636) (LLVM build 2099)\00", section "llvm.metadata"           ; <[57 x i8]*> [#uses=1]
+@llvm.dbg.compile_unit = internal constant %llvm.dbg.compile_unit.type { i32 458769, { }* bitcast (%llvm.dbg.anchor.type* @llvm.dbg.compile_units to { }*), i32 1, i8* getelementptr ([4 x i8]* @.str, i32 0, i32 0), i8* getelementptr ([5 x i8]* @.str1, i32 0, i32 0), i8* getelementptr ([57 x i8]* @.str2, i32 0, i32 0), i1 true, i1 false, i8* null, i32 0 }, section "llvm.metadata"           ; <%llvm.dbg.compile_unit.type*> [#uses=1]
+@.str3 = internal constant [4 x i8] c"int\00", section "llvm.metadata"         ; <[4 x i8]*> [#uses=1]
+@llvm.dbg.basictype = internal constant %llvm.dbg.basictype.type { i32 458788, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i8* getelementptr ([4 x i8]* @.str3, i32 0, i32 0), { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 0, i64 32, i64 32, i64 0, i32 0, i32 5 }, section "llvm.metadata"               ; <%llvm.dbg.basictype.type*> [#uses=1]
+@llvm.dbg.array = internal constant [1 x { }*] [ { }* bitcast (%llvm.dbg.basictype.type* @llvm.dbg.basictype to { }*) ], section "llvm.metadata"               ; <[1 x { }*]*> [#uses=1]
+@llvm.dbg.composite = internal constant %llvm.dbg.composite.type { i32 458773, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i8* null, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 0, i64 0, i64 0, i64 0, i32 0, { }* null, { }* bitcast ([1 x { }*]* @llvm.dbg.array to { }*), i32 0 }, section "llvm.metadata"            ; <%llvm.dbg.composite.type*> [#uses=1]
+@llvm.dbg.subprograms = linkonce constant %llvm.dbg.anchor.type { i32 458752, i32 46 }, section "llvm.metadata"                ; <%llvm.dbg.anchor.type*> [#uses=1]
+@.str4 = internal constant [5 x i8] c"main\00", section "llvm.metadata"                ; <[5 x i8]*> [#uses=1]
+@llvm.dbg.subprogram = internal constant %llvm.dbg.subprogram.type { i32 458798, { }* bitcast (%llvm.dbg.anchor.type* @llvm.dbg.subprograms to { }*), { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i8* getelementptr ([5 x i8]* @.str4, i32 0, i32 0), i8* getelementptr ([5 x i8]* @.str4, i32 0, i32 0), i8* null, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 3, { }* bitcast (%llvm.dbg.composite.type* @llvm.dbg.composite to { }*), i1 false, i1 true }, section "llvm.metadata"              ; <%llvm.dbg.subprogram.type*> [#uses=1]
+@llvm.dbg.derivedtype = internal constant %llvm.dbg.derivedtype.type { i32 458767, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i8* null, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 0, i64 32, i64 32, i64 0, i32 0, { }* bitcast (%llvm.dbg.basictype.type* @llvm.dbg.basictype to { }*) }, section "llvm.metadata"              ; <%llvm.dbg.derivedtype.type*> [#uses=1]
+@.str5 = internal constant [6 x i8] c"i_ptr\00", section "llvm.metadata"               ; <[6 x i8]*> [#uses=1]
+@llvm.dbg.variable = internal constant %llvm.dbg.variable.type { i32 459008, { }* bitcast (%llvm.dbg.subprogram.type* @llvm.dbg.subprogram to { }*), i8* getelementptr ([6 x i8]* @.str5, i32 0, i32 0), { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 5, { }* bitcast (%llvm.dbg.derivedtype.type* @llvm.dbg.derivedtype to { }*) }, section "llvm.metadata"                ; <%llvm.dbg.variable.type*> [#uses=0]
+@sillyArray.1433 = internal global [8 x i32] [ i32 2, i32 3, i32 5, i32 7, i32 11, i32 13, i32 17, i32 19 ]            ; <[8 x i32]*> [#uses=1]
+@llvm.dbg.subrange = internal constant %llvm.dbg.subrange.type { i32 458785, i64 0, i64 7 }, section "llvm.metadata"           ; <%llvm.dbg.subrange.type*> [#uses=1]
+@llvm.dbg.array6 = internal constant [1 x { }*] [ { }* bitcast (%llvm.dbg.subrange.type* @llvm.dbg.subrange to { }*) ], section "llvm.metadata"                ; <[1 x { }*]*> [#uses=1]
+@llvm.dbg.composite7 = internal constant %llvm.dbg.composite.type { i32 458753, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i8* null, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 0, i64 256, i64 32, i64 0, i32 0, { }* bitcast (%llvm.dbg.basictype.type* @llvm.dbg.basictype to { }*), { }* bitcast ([1 x { }*]* @llvm.dbg.array6 to { }*), i32 0 }, section "llvm.metadata"            ; <%llvm.dbg.composite.type*> [#uses=1]
+@llvm.dbg.global_variables = linkonce constant %llvm.dbg.anchor.type { i32 458752, i32 52 }, section "llvm.metadata"           ; <%llvm.dbg.anchor.type*> [#uses=1]
+@.str8 = internal constant [16 x i8] c"sillyArray.1433\00", section "llvm.metadata"            ; <[16 x i8]*> [#uses=1]
+@.str9 = internal constant [11 x i8] c"sillyArray\00", section "llvm.metadata"         ; <[11 x i8]*> [#uses=1]
+@llvm.dbg.global_variable42 = internal constant %llvm.dbg.global_variable.type { i32 458804, { }* bitcast (%llvm.dbg.anchor.type* @llvm.dbg.global_variables to { }*), { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i8* getelementptr ([16 x i8]* @.str8, i32 0, i32 0), i8* getelementptr ([11 x i8]* @.str9, i32 0, i32 0), i8* null, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*), i32 4, { }* bitcast (%llvm.dbg.composite.type* @llvm.dbg.composite7 to { }*), i1 true, i1 true, { }* bitcast ([8 x i32]* @sillyArray.1433 to { }*) }, section "llvm.metadata"               ; <%llvm.dbg.global_variable.type*> [#uses=0]
+
+define i32 @main() nounwind {
+entry:
+       %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
+       call void @llvm.dbg.func.start({ }* bitcast (%llvm.dbg.subprogram.type* @llvm.dbg.subprogram to { }*))
+       call void @llvm.dbg.stoppoint(i32 5, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*))
+       call void @llvm.dbg.stoppoint(i32 6, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*))
+       call void @llvm.dbg.stoppoint(i32 6, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*))
+       call void @llvm.dbg.region.end({ }* bitcast (%llvm.dbg.subprogram.type* @llvm.dbg.subprogram to { }*))
+       ret i32 0
+}
+
+declare void @llvm.dbg.func.start({ }*) nounwind
+
+declare void @llvm.dbg.declare({ }*, { }*) nounwind
+
+declare void @llvm.dbg.stoppoint(i32, i32, { }*) nounwind
+
+declare void @llvm.dbg.region.end({ }*) nounwind