[llvm-commits] [llvm] r133905 - in /llvm/trunk: lib/Transforms/Scalar/ScalarReplAggregates.cpp test/Transforms/ScalarRepl/memcpy-from-global.ll
Nick Lewycky
nicholas at mxc.ca
Sun Jun 26 22:40:02 PDT 2011
Author: nicholas
Date: Mon Jun 27 00:40:02 2011
New Revision: 133905
URL: http://llvm.org/viewvc/llvm-project?rev=133905&view=rev
Log:
Teach one piece of scalarrepl to handle lifetime markers. When transforming an
alloca that only holds a copy of a global and we're going to replace the users
of the alloca with that global, just nuke the lifetime intrinsics. Part of
PR10121.
Modified:
llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll
Modified: llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp?rev=133905&r1=133904&r2=133905&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp Mon Jun 27 00:40:02 2011
@@ -152,7 +152,8 @@
void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI,
SmallVector<AllocaInst*, 32> &NewElts);
- static MemTransferInst *isOnlyCopiedFromConstantGlobal(AllocaInst *AI);
+ static MemTransferInst *isOnlyCopiedFromConstantGlobal(
+ AllocaInst *AI, SmallVector<Instruction*, 4> &ToDelete);
};
// SROA_DT - SROA that uses DominatorTree.
@@ -1443,8 +1444,8 @@
// performScalarRepl - This algorithm is a simple worklist driven algorithm,
-// which runs on all of the malloc/alloca instructions in the function, removing
-// them if they are only used by getelementptr instructions.
+// which runs on all of the alloca instructions in the function, removing them
+// if they are only used by getelementptr instructions.
//
bool SROA::performScalarRepl(Function &F) {
std::vector<AllocaInst*> WorkList;
@@ -1478,12 +1479,15 @@
// the constant global instead. This is commonly produced by the CFE by
// constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
// is only subsequently read.
- if (MemTransferInst *TheCopy = isOnlyCopiedFromConstantGlobal(AI)) {
+ SmallVector<Instruction *, 4> ToDelete;
+ if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(AI, ToDelete)) {
DEBUG(dbgs() << "Found alloca equal to global: " << *AI << '\n');
- DEBUG(dbgs() << " memcpy = " << *TheCopy << '\n');
- Constant *TheSrc = cast<Constant>(TheCopy->getSource());
+ DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
+ for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
+ ToDelete[i]->eraseFromParent();
+ Constant *TheSrc = cast<Constant>(Copy->getSource());
AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
- TheCopy->eraseFromParent(); // Don't mutate the global.
+ Copy->eraseFromParent(); // Don't mutate the global.
AI->eraseFromParent();
++NumGlobals;
Changed = true;
@@ -2507,8 +2511,14 @@
/// the uses. If we see a memcpy/memmove that targets an unoffseted pointer to
/// the alloca, and if the source pointer is a pointer to a constant global, we
/// can optimize this.
-static bool isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
- bool isOffset) {
+static bool
+isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
+ bool isOffset,
+ SmallVector<Instruction *, 4> &LifetimeMarkers) {
+ // We track lifetime intrinsics as we encounter them. If we decide to go
+ // ahead and replace the value with the global, this lets the caller quickly
+ // eliminate the markers.
+
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
User *U = cast<Instruction>(*UI);
@@ -2520,7 +2530,8 @@
if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
// If uses of the bitcast are ok, we are ok.
- if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, isOffset))
+ if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, isOffset,
+ LifetimeMarkers))
return false;
continue;
}
@@ -2528,7 +2539,8 @@
// If the GEP has all zero indices, it doesn't offset the pointer. If it
// doesn't, it does.
if (!isOnlyCopiedFromConstantGlobal(GEP, TheCopy,
- isOffset || !GEP->hasAllZeroIndices()))
+ isOffset || !GEP->hasAllZeroIndices(),
+ LifetimeMarkers))
return false;
continue;
}
@@ -2554,6 +2566,16 @@
continue;
}
+ // Lifetime intrinsics can be handled by the caller.
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
+ II->getIntrinsicID() == Intrinsic::lifetime_end) {
+ assert(II->use_empty() && "Lifetime markers have no result to use!");
+ LifetimeMarkers.push_back(II);
+ continue;
+ }
+ }
+
// If this is isn't our memcpy/memmove, reject it as something we can't
// handle.
MemTransferInst *MI = dyn_cast<MemTransferInst>(U);
@@ -2590,9 +2612,11 @@
/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
/// modified by a copy from a constant global. If we can prove this, we can
/// replace any uses of the alloca with uses of the global directly.
-MemTransferInst *SROA::isOnlyCopiedFromConstantGlobal(AllocaInst *AI) {
+MemTransferInst *
+SROA::isOnlyCopiedFromConstantGlobal(AllocaInst *AI,
+ SmallVector<Instruction*, 4> &ToDelete) {
MemTransferInst *TheCopy = 0;
- if (::isOnlyCopiedFromConstantGlobal(AI, TheCopy, false))
+ if (::isOnlyCopiedFromConstantGlobal(AI, TheCopy, false, ToDelete))
return TheCopy;
return 0;
}
Modified: llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll?rev=133905&r1=133904&r2=133905&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll (original)
+++ llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll Mon Jun 27 00:40:02 2011
@@ -93,4 +93,18 @@
ret void
}
+declare void @llvm.lifetime.start(i64, i8*)
+define void @test5() {
+ %A = alloca %T
+ %a = bitcast %T* %A to i8*
+ call void @llvm.lifetime.start(i64 -1, i8* %a)
+ call void @llvm.memcpy.p0i8.p0i8.i64(i8* %a, i8* bitcast (%T* @G to i8*), i64 124, i32 4, i1 false)
+ call void @baz(i8* byval %a)
+; CHECK: @test5
+; CHECK-NEXT: %a = bitcast %T* @G to i8*
+; CHECK-NEXT: call void @baz(i8* byval %a)
+ ret void
+}
+
+
declare void @baz(i8* byval)
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