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Atomic load/store handling for the passes using memdep (GVN, DSE, memcpyopt). 

llvm-svn: 137888
This commit is contained in:
Eli Friedman 2011-08-17 22:22:24 +00:00
parent 5b8ad40664
commit 9a468153e1
6 changed files with 239 additions and 9 deletions
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8
llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
View File

@ -213,9 +213,9 @@ getLocForRead(Instruction *Inst, AliasAnalysis &AA) {
/// isRemovable - If the value of this instruction and the memory it writes to
/// is unused, may we delete this instruction?
static bool isRemovable(Instruction *I) {
// Don't remove volatile stores.
// Don't remove volatile/atomic stores.
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return !SI->isVolatile();
return SI->isUnordered();
IntrinsicInst *II = cast<IntrinsicInst>(I);
switch (II->getIntrinsicID()) {
@ -447,7 +447,7 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (LoadInst *DepLoad = dyn_cast<LoadInst>(InstDep.getInst())) {
if (SI->getPointerOperand() == DepLoad->getPointerOperand() &&
SI->getOperand(0) == DepLoad && !SI->isVolatile()) {
SI->getOperand(0) == DepLoad && isRemovable(SI)) {
DEBUG(dbgs() << "DSE: Remove Store Of Load from same pointer:\n "
<< "LOAD: " << *DepLoad << "\n STORE: " << *SI << '\n');
@ -670,6 +670,8 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
// If we encounter a use of the pointer, it is no longer considered dead
if (LoadInst *L = dyn_cast<LoadInst>(BBI)) {
if (!L->isUnordered()) // Be conservative with atomic/volatile load
break;
LoadedLoc = AA->getLocation(L);
} else if (VAArgInst *V = dyn_cast<VAArgInst>(BBI)) {
LoadedLoc = AA->getLocation(V);

6
llvm/lib/Transforms/Scalar/GVN.cpp
View File

@ -982,8 +982,8 @@ static Value *GetLoadValueForLoad(LoadInst *SrcVal, unsigned Offset,
unsigned SrcValSize = TD.getTypeStoreSize(SrcVal->getType());
unsigned LoadSize = TD.getTypeStoreSize(LoadTy);
if (Offset+LoadSize > SrcValSize) {
assert(!SrcVal->isVolatile() && "Cannot widen volatile load!");
assert(isa<IntegerType>(SrcVal->getType())&&"Can't widen non-integer load");
assert(SrcVal->isSimple() && "Cannot widen volatile/atomic load!");
assert(SrcVal->getType()->isIntegerTy() && "Can't widen non-integer load");
// If we have a load/load clobber an DepLI can be widened to cover this
// load, then we should widen it to the next power of 2 size big enough!
unsigned NewLoadSize = Offset+LoadSize;
@ -1669,7 +1669,7 @@ bool GVN::processLoad(LoadInst *L) {
if (!MD)
return false;
if (L->isVolatile())
if (!L->isSimple())
return false;
if (L->use_empty()) {

6
llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
View File

@ -384,7 +384,7 @@ Instruction *MemCpyOpt::tryMergingIntoMemset(Instruction *StartInst,
if (StoreInst *NextStore = dyn_cast<StoreInst>(BI)) {
// If this is a store, see if we can merge it in.
if (NextStore->isVolatile()) break;
if (!NextStore->isSimple()) break;
// Check to see if this stored value is of the same byte-splattable value.
if (ByteVal != isBytewiseValue(NextStore->getOperand(0)))
@ -479,7 +479,7 @@ Instruction *MemCpyOpt::tryMergingIntoMemset(Instruction *StartInst,
bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
if (SI->isVolatile()) return false;
if (!SI->isSimple()) return false;
if (TD == 0) return false;
@ -487,7 +487,7 @@ bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
// happen to be using a load-store pair to implement it, rather than
// a memcpy.
if (LoadInst *LI = dyn_cast<LoadInst>(SI->getOperand(0))) {
if (!LI->isVolatile() && LI->hasOneUse() &&
if (LI->isSimple() && LI->hasOneUse() &&
LI->getParent() == SI->getParent()) {
MemDepResult ldep = MD->getDependency(LI);
CallInst *C = 0;

107
llvm/test/Transforms/DeadStoreElimination/atomic.ll Normal file
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@ -0,0 +1,107 @@
; RUN: opt -basicaa -dse -S < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-macosx10.7.0"
; Sanity tests for atomic stores.
; Note that it turns out essentially every transformation DSE does is legal on
; atomic ops, just some transformations are not allowed across them.
@x = common global i32 0, align 4
@y = common global i32 0, align 4
declare void @randomop(i32*)
; DSE across unordered store (allowed)
define void @test1() nounwind uwtable ssp {
; CHECK: test1
; CHECK-NOT: store i32 0
; CHECK: store i32 1
entry:
store i32 0, i32* @x
store atomic i32 0, i32* @y unordered, align 4
store i32 1, i32* @x
ret void
}
; DSE across seq_cst load (allowed in theory; not implemented ATM)
define i32 @test2() nounwind uwtable ssp {
; CHECK: test2
; CHECK: store i32 0
; CHECK: store i32 1
entry:
store i32 0, i32* @x
%x = load atomic i32* @y seq_cst, align 4
store i32 1, i32* @x
ret i32 %x
}
; DSE across seq_cst store (store before atomic store must not be removed)
define void @test3() nounwind uwtable ssp {
; CHECK: test3
; CHECK: store i32
; CHECK: store atomic i32 2
entry:
store i32 0, i32* @x
store atomic i32 2, i32* @y seq_cst, align 4
store i32 1, i32* @x
ret void
}
; DSE remove unordered store (allowed)
define void @test4() nounwind uwtable ssp {
; CHECK: test4
; CHECK-NOT: store atomic
; CHECK: store i32 1
entry:
store atomic i32 0, i32* @x unordered, align 4
store i32 1, i32* @x
ret void
}
; DSE unordered store overwriting non-atomic store (allowed)
define void @test5() nounwind uwtable ssp {
; CHECK: test5
; CHECK: store atomic i32 1
entry:
store i32 0, i32* @x
store atomic i32 1, i32* @x unordered, align 4
ret void
}
; DSE no-op unordered atomic store (allowed)
define void @test6() nounwind uwtable ssp {
; CHECK: test6
; CHECK-NOT: store
; CHECK: ret void
entry:
%x = load atomic i32* @x unordered, align 4
store atomic i32 %x, i32* @x unordered, align 4
ret void
}
; DSE seq_cst store (be conservative; DSE doesn't have infrastructure
; to reason about atomic operations).
define void @test7() nounwind uwtable ssp {
; CHECK: test7
; CHECK: store atomic
entry:
%a = alloca i32
store atomic i32 0, i32* %a seq_cst, align 4
ret void
}
; DSE and seq_cst load (be conservative; DSE doesn't have infrastructure
; to reason about atomic operations).
define i32 @test8() nounwind uwtable ssp {
; CHECK: test8
; CHECK: store
; CHECK: load atomic
entry:
%a = alloca i32
call void @randomop(i32* %a)
store i32 0, i32* %a, align 4
%x = load atomic i32* @x seq_cst, align 4
ret i32 %x
}

80
llvm/test/Transforms/GVN/atomic.ll Normal file
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@ -0,0 +1,80 @@
; RUN: opt -basicaa -gvn -S < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-macosx10.7.0"
@x = common global i32 0, align 4
@y = common global i32 0, align 4
; GVN across unordered store (allowed)
define i32 @test1() nounwind uwtable ssp {
; CHECK: test1
; CHECK: add i32 %x, %x
entry:
%x = load i32* @y
store atomic i32 %x, i32* @x unordered, align 4
%y = load i32* @y
%z = add i32 %x, %y
ret i32 %z
}
; GVN across seq_cst store (allowed in theory; not implemented ATM)
define i32 @test2() nounwind uwtable ssp {
; CHECK: test2
; CHECK: add i32 %x, %y
entry:
%x = load i32* @y
store atomic i32 %x, i32* @x seq_cst, align 4
%y = load i32* @y
%z = add i32 %x, %y
ret i32 %z
}
; GVN across unordered load (allowed)
define i32 @test3() nounwind uwtable ssp {
; CHECK: test3
; CHECK: add i32 %x, %x
entry:
%x = load i32* @y
%y = load atomic i32* @x unordered, align 4
%z = load i32* @y
%a = add i32 %x, %z
%b = add i32 %y, %a
ret i32 %b
}
; GVN across acquire load (load after atomic load must not be removed)
define i32 @test4() nounwind uwtable ssp {
; CHECK: test4
; CHECK: load atomic i32* @x
; CHECK: load i32* @y
entry:
%x = load i32* @y
%y = load atomic i32* @x seq_cst, align 4
%x2 = load i32* @y
%x3 = add i32 %x, %x2
%y2 = add i32 %y, %x3
ret i32 %y2
}
; GVN load to unordered load (allowed)
define i32 @test5() nounwind uwtable ssp {
; CHECK: test5
; CHECK: add i32 %x, %x
entry:
%x = load atomic i32* @x unordered, align 4
%y = load i32* @x
%z = add i32 %x, %y
ret i32 %z
}
; GVN unordered load to load (unordered load must not be removed)
define i32 @test6() nounwind uwtable ssp {
; CHECK: test6
; CHECK: load atomic i32* @x unordered
entry:
%x = load i32* @x
%x2 = load atomic i32* @x unordered, align 4
%x3 = add i32 %x, %x2
ret i32 %x3
}

41
llvm/test/Transforms/MemCpyOpt/atomic.ll Normal file
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@ -0,0 +1,41 @@
; RUN: opt -basicaa -memcpyopt -S < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-macosx10.7.0"
@x = global i32 0
declare void @otherf(i32*)
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
; memcpyopt should not touch atomic ops
define void @test1() nounwind uwtable ssp {
; CHECK: test1
; CHECK: store atomic
%x = alloca [101 x i32], align 16
%bc = bitcast [101 x i32]* %x to i8*
call void @llvm.memset.p0i8.i64(i8* %bc, i8 0, i64 400, i32 16, i1 false)
%gep1 = getelementptr inbounds [101 x i32]* %x, i32 0, i32 100
store atomic i32 0, i32* %gep1 unordered, align 4
%gep2 = getelementptr inbounds [101 x i32]* %x, i32 0, i32 0
call void @otherf(i32* %gep2)
ret void
}
; memcpyopt across unordered store
define void @test2() nounwind uwtable ssp {
; CHECK: test2
; CHECK: call
; CHECK-NEXT: store atomic
; CHECK-NEXT: call
%old = alloca i32
%new = alloca i32
call void @otherf(i32* nocapture %old)
store atomic i32 0, i32* @x unordered, align 4
%v = load i32* %old
store i32 %v, i32* %new
call void @otherf(i32* nocapture %new)
ret void
}