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Cleanup/remove some parts of the lifetime region handling code in memdep and GVN,

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per Chris' comments.  Adjust testcases to match.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90304 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2009-12-02 07:35:19 +00:00
parent 720e790480
commit 9ff5a23186
4 changed files with 21 additions and 44 deletions
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29
lib/Analysis/MemoryDependenceAnalysis.cpp
View File

@ -186,15 +186,17 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
}
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
// Debug intrinsics don't cause dependences.
if (isa<DbgInfoIntrinsic>(Inst)) continue;
// If we pass an invariant-end marker, then we've just entered an
// invariant region and can start ignoring dependencies.
if (II->getIntrinsicID() == Intrinsic::invariant_end) {
uint64_t InvariantSize = ~0ULL;
if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(2)))
InvariantSize = CI->getZExtValue();
AliasAnalysis::AliasResult R =
AA->alias(II->getOperand(3), InvariantSize, MemPtr, MemSize);
// FIXME: This only considers queries directly on the invariant-tagged
// pointer, not on query pointers that are indexed off of them. It'd
// be nice to handle that at some point.
AliasAnalysis::AliasResult R =
AA->alias(II->getOperand(3), ~0ULL, MemPtr, ~0ULL);
if (R == AliasAnalysis::MustAlias) {
InvariantTag = II->getOperand(1);
continue;
@ -202,14 +204,12 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
// If we reach a lifetime begin or end marker, then the query ends here
// because the value is undefined.
} else if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
II->getIntrinsicID() == Intrinsic::lifetime_end) {
uint64_t InvariantSize = ~0ULL;
if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(1)))
InvariantSize = CI->getZExtValue();
} else if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
// FIXME: This only considers queries directly on the invariant-tagged
// pointer, not on query pointers that are indexed off of them. It'd
// be nice to handle that at some point.
AliasAnalysis::AliasResult R =
AA->alias(II->getOperand(2), InvariantSize, MemPtr, MemSize);
AA->alias(II->getOperand(2), ~0ULL, MemPtr, ~0ULL);
if (R == AliasAnalysis::MustAlias)
return MemDepResult::getDef(II);
}
@ -219,9 +219,6 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
// at this point. Nothing a load depends on can live in an invariant region.
if (isLoad && InvariantTag) continue;
// Debug intrinsics don't cause dependences.
if (isa<DbgInfoIntrinsic>(Inst)) continue;
// Values depend on loads if the pointers are must aliased. This means that
// a load depends on another must aliased load from the same value.
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {

14
lib/Transforms/Scalar/GVN.cpp
View File

@ -1187,10 +1187,9 @@ static Value *ConstructSSAForLoadSet(LoadInst *LI,
return V;
}
static bool isLifetimeStartOrEnd(Instruction *Inst) {
static bool isLifetimeStart(Instruction *Inst) {
if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst))
return II->getIntrinsicID() == Intrinsic::lifetime_start ||
II->getIntrinsicID() == Intrinsic::lifetime_end;
return II->getIntrinsicID() == Intrinsic::lifetime_start;
return false;
}
@ -1262,8 +1261,8 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
// Loading the allocation -> undef.
if (isa<AllocaInst>(DepInst) || isMalloc(DepInst) ||
// Loading immediately after lifetime begin or end -> undef.
isLifetimeStartOrEnd(DepInst)) {
// Loading immediately after lifetime begin -> undef.
isLifetimeStart(DepInst)) {
ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
UndefValue::get(LI->getType())));
continue;
@ -1635,11 +1634,10 @@ bool GVN::processLoad(LoadInst *L, SmallVectorImpl<Instruction*> &toErase) {
return true;
}
// If this load occurs either right after a lifetime begin or a lifetime end,
// If this load occurs either right after a lifetime begin,
// then the loaded value is undefined.
if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(DepInst)) {
if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
II->getIntrinsicID() == Intrinsic::lifetime_end) {
if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
toErase.push_back(L);
NumGVNLoad++;

18
test/Transforms/DeadStoreElimination/lifetime-simple.ll
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@ -1,18 +0,0 @@
; RUN: opt < %s -dse -S | FileCheck %s
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin7"
define i8 @test2(i8* %P) nounwind {
; CHECK: @test2
; CHECK-NOT: store i8 1
; CHECK: ret i8 0
entry:
call void @llvm.lifetime.start(i64 32, i8* %P)
call void @llvm.lifetime.end(i64 32, i8* %P)
store i8 1, i8* %P
ret i8 0
}
declare {}* @llvm.lifetime.start(i64 %S, i8* nocapture %P) readonly
declare void @llvm.lifetime.end(i64 %S, i8* nocapture %P)

4
test/Transforms/GVN/lifetime-simple.ll
View File

@ -4,9 +4,9 @@ target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f3
target triple = "i386-apple-darwin7"
define i8 @test(i8* %P) nounwind {
; CHECK: @test
; CHECK: lifetime.start
; CHECK-NOT: load
; CHECK: ret i8 undef
; CHECK: lifetime.end
entry:
call void @llvm.lifetime.start(i64 32, i8* %P)
%0 = load i8* %P