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-rw-r--r--lib/Transforms/IPO/DeadArgumentElimination.cpp93
-rw-r--r--test/Transforms/DeadArgElim/deadexternal.ll12
2 files changed, 82 insertions, 23 deletions
diff --git a/lib/Transforms/IPO/DeadArgumentElimination.cpp b/lib/Transforms/IPO/DeadArgumentElimination.cpp
index 1749b1eff3..d99dd7fd94 100644
--- a/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ b/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -30,6 +30,7 @@
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
@@ -50,7 +51,7 @@ namespace {
/// argument. Used so that arguments and return values can be used
/// interchangably.
struct RetOrArg {
- RetOrArg(const Function* F, unsigned Idx, bool IsArg) : F(F), Idx(Idx),
+ RetOrArg(const Function *F, unsigned Idx, bool IsArg) : F(F), Idx(Idx),
IsArg(IsArg) {}
const Function *F;
unsigned Idx;
@@ -140,6 +141,7 @@ namespace {
void MarkLive(const Function &F);
void PropagateLiveness(const RetOrArg &RA);
bool RemoveDeadStuffFromFunction(Function *F);
+ bool RemoveDeadParamsFromCallersOf(Function *F);
bool DeleteDeadVarargs(Function &Fn);
};
}
@@ -280,7 +282,7 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
/// for void functions and 1 for functions not returning a struct. It returns
/// the number of struct elements for functions returning a struct.
static unsigned NumRetVals(const Function *F) {
- if (F->getReturnType() == Type::getVoidTy(F->getContext()))
+ if (F->getReturnType()->isVoidTy())
return 0;
else if (const StructType *STy = dyn_cast<StructType>(F->getReturnType()))
return STy->getNumElements();
@@ -305,7 +307,7 @@ DAE::Liveness DAE::MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses) {
/// SurveyUse - This looks at a single use of an argument or return value
/// and determines if it should be alive or not. Adds this use to MaybeLiveUses
-/// if it causes the used value to become MaybeAlive.
+/// if it causes the used value to become MaybeLive.
///
/// RetValNum is the return value number to use when this use is used in a
/// return instruction. This is used in the recursion, you should always leave
@@ -396,7 +398,7 @@ DAE::Liveness DAE::SurveyUses(Value *V, UseVector &MaybeLiveUses) {
// any callers use the return value. This fills in the LiveValues set and Uses
// map.
//
-// We consider arguments of non-internal functions to be intrinsically alive as
+// We consider arguments of overridable functions to be intrinsically alive as
// well as arguments to functions which have their "address taken".
//
void DAE::SurveyFunction(Function &F) {
@@ -420,9 +422,16 @@ void DAE::SurveyFunction(Function &F) {
return;
}
- if (!F.hasLocalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) {
+ if ((F.isDeclaration() || F.mayBeOverridden()) &&
+ (!ShouldHackArguments() || F.isIntrinsic())) {
MarkLive(F);
return;
+ } else if (!F.hasLocalLinkage()) {
+ DEBUG(dbgs() << "DAE - Intrinsically live return from " << F.getName()
+ << "\n");
+ // Mark the return values alive.
+ for (unsigned i = 0, e = NumRetVals(&F); i != e; ++i)
+ MarkLive(CreateRet(&F, i));
}
DEBUG(dbgs() << "DAE - Inspecting callers for fn: " << F.getName() << "\n");
@@ -531,14 +540,14 @@ void DAE::MarkValue(const RetOrArg &RA, Liveness L,
/// values (according to Uses) live as well.
void DAE::MarkLive(const Function &F) {
DEBUG(dbgs() << "DAE - Intrinsically live fn: " << F.getName() << "\n");
- // Mark the function as live.
- LiveFunctions.insert(&F);
- // Mark all arguments as live.
- for (unsigned i = 0, e = F.arg_size(); i != e; ++i)
- PropagateLiveness(CreateArg(&F, i));
- // Mark all return values as live.
- for (unsigned i = 0, e = NumRetVals(&F); i != e; ++i)
- PropagateLiveness(CreateRet(&F, i));
+ // Mark the function as live.
+ LiveFunctions.insert(&F);
+ // Mark all arguments as live.
+ for (unsigned i = 0, e = F.arg_size(); i != e; ++i)
+ PropagateLiveness(CreateArg(&F, i));
+ // Mark all return values as live.
+ for (unsigned i = 0, e = NumRetVals(&F); i != e; ++i)
+ PropagateLiveness(CreateRet(&F, i));
}
/// MarkLive - Mark the given return value or argument as live. Additionally,
@@ -603,8 +612,8 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
// -1 means unused, other numbers are the new index
SmallVector<int, 5> NewRetIdxs(RetCount, -1);
std::vector<const Type*> RetTypes;
- if (RetTy == Type::getVoidTy(F->getContext())) {
- NRetTy = Type::getVoidTy(F->getContext());
+ if (RetTy->isVoidTy()) {
+ NRetTy = RetTy;
} else {
const StructType *STy = dyn_cast<StructType>(RetTy);
if (STy)
@@ -653,7 +662,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
// values. Otherwise, ensure that we don't have any conflicting attributes
// here. Currently, this should not be possible, but special handling might be
// required when new return value attributes are added.
- if (NRetTy == Type::getVoidTy(F->getContext()))
+ if (NRetTy->isVoidTy())
RAttrs &= ~Attribute::typeIncompatible(NRetTy);
else
assert((RAttrs & Attribute::typeIncompatible(NRetTy)) == 0
@@ -705,8 +714,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
}
// Create the new function type based on the recomputed parameters.
- FunctionType *NFTy = FunctionType::get(NRetTy, Params,
- FTy->isVarArg());
+ FunctionType *NFTy = FunctionType::get(NRetTy, Params, FTy->isVarArg());
// No change?
if (NFTy == FTy)
@@ -791,7 +799,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
// Return type not changed? Just replace users then.
Call->replaceAllUsesWith(New);
New->takeName(Call);
- } else if (New->getType() == Type::getVoidTy(F->getContext())) {
+ } else if (New->getType()->isVoidTy()) {
// Our return value has uses, but they will get removed later on.
// Replace by null for now.
Call->replaceAllUsesWith(Constant::getNullValue(Call->getType()));
@@ -867,7 +875,7 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
Value *RetVal;
- if (NFTy->getReturnType() == Type::getVoidTy(F->getContext())) {
+ if (NFTy->getReturnType()->isVoidTy()) {
RetVal = 0;
} else {
assert (isa<StructType>(RetTy));
@@ -908,6 +916,42 @@ bool DAE::RemoveDeadStuffFromFunction(Function *F) {
return true;
}
+bool DAE::RemoveDeadParamsFromCallersOf(Function *F) {
+ // Don't modify fully live functions
+ if (LiveFunctions.count(F))
+ return false;
+
+ // Make a list of the dead arguments.
+ SmallVector<int, 10> ArgDead;
+ unsigned i = 0;
+ for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
+ I != E; ++I, ++i) {
+ RetOrArg Arg = CreateArg(F, i);
+ if (!LiveValues.count(Arg))
+ ArgDead.push_back(i);
+ }
+ if (ArgDead.empty())
+ return false;
+
+ bool MadeChange = false;
+ for (Function::use_iterator I = F->use_begin(), E = F->use_end();
+ I != E; ++I) {
+ CallSite CS = CallSite::get(*I);
+ if (CS.getInstruction() && CS.isCallee(I)) {
+ for (unsigned i = 0, e = ArgDead.size(); i != e; ++i) {
+ Value *A = CS.getArgument(ArgDead[i]);
+ if (!isa<UndefValue>(A)) {
+ MadeChange = true;
+ CS.setArgument(ArgDead[i], UndefValue::get(A->getType()));
+ RecursivelyDeleteTriviallyDeadInstructions(A);
+ }
+ }
+ }
+ }
+
+ return MadeChange;
+}
+
bool DAE::runOnModule(Module &M) {
bool Changed = false;
@@ -931,12 +975,15 @@ bool DAE::runOnModule(Module &M) {
SurveyFunction(*I);
// Now, remove all dead arguments and return values from each function in
- // turn
+ // turn.
for (Module::iterator I = M.begin(), E = M.end(); I != E; ) {
- // Increment now, because the function will probably get removed (ie
+ // Increment now, because the function will probably get removed (ie.
// replaced by a new one).
Function *F = I++;
- Changed |= RemoveDeadStuffFromFunction(F);
+ if (F->hasLocalLinkage())
+ Changed |= RemoveDeadStuffFromFunction(F);
+ else
+ Changed |= RemoveDeadParamsFromCallersOf(F);
}
return Changed;
}
diff --git a/test/Transforms/DeadArgElim/deadexternal.ll b/test/Transforms/DeadArgElim/deadexternal.ll
new file mode 100644
index 0000000000..84341781da
--- /dev/null
+++ b/test/Transforms/DeadArgElim/deadexternal.ll
@@ -0,0 +1,12 @@
+; RUN: opt -deadargelim -S %s | FileCheck %s
+
+define void @test(i32) {
+ ret void
+}
+
+define void @foo() {
+ call void @test(i32 0)
+ ret void
+; CHECK: @foo
+; CHECK: i32 undef
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-18 01:41:17 +0000