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If a global constant is dead then global's debug info should not prevent the optimizer in deleting the global. And while deleting global, delete global's debug info also.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65994 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2009-03-04 01:22:23 +00:00
parent 0d6596b7bf
commit 7f6179d1d8
2 changed files with 72 additions and 6 deletions
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26
lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -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);

52
test/Transforms/GlobalOpt/2009-03-03-dbg.ll Normal file
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@ -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