[llvm-branch-commits] [llvm-branch] r89739 - in /llvm/branches/Apple/Zoidberg: include/llvm/Analysis/CaptureTracking.h lib/Analysis/BasicAliasAnalysis.cpp lib/Analysis/CaptureTracking.cpp lib/Transforms/IPO/FunctionAttrs.cpp
Bob Wilson
bob.wilson at apple.com
Mon Nov 23 21:32:21 PST 2009
Author: bwilson
Date: Mon Nov 23 23:32:21 2009
New Revision: 89739
URL: http://llvm.org/viewvc/llvm-project?rev=89739&view=rev
Log:
Reapply Dan's changes 89389, 89398, 89436, and 89485.
Modified:
llvm/branches/Apple/Zoidberg/include/llvm/Analysis/CaptureTracking.h
llvm/branches/Apple/Zoidberg/lib/Analysis/BasicAliasAnalysis.cpp
llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp
llvm/branches/Apple/Zoidberg/lib/Transforms/IPO/FunctionAttrs.cpp
Modified: llvm/branches/Apple/Zoidberg/include/llvm/Analysis/CaptureTracking.h
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Zoidberg/include/llvm/Analysis/CaptureTracking.h?rev=89739&r1=89738&r2=89739&view=diff
==============================================================================
--- llvm/branches/Apple/Zoidberg/include/llvm/Analysis/CaptureTracking.h (original)
+++ llvm/branches/Apple/Zoidberg/include/llvm/Analysis/CaptureTracking.h Mon Nov 23 23:32:21 2009
@@ -21,8 +21,12 @@
/// by the enclosing function (which is required to exist). This routine can
/// be expensive, so consider caching the results. The boolean ReturnCaptures
/// specifies whether returning the value (or part of it) from the function
+ /// counts as capturing it or not. The boolean StoreCaptures specified whether
+ /// storing the value (or part of it) into memory anywhere automatically
/// counts as capturing it or not.
- bool PointerMayBeCaptured(const Value *V, bool ReturnCaptures);
+ bool PointerMayBeCaptured(const Value *V,
+ bool ReturnCaptures,
+ bool StoreCaptures);
} // end namespace llvm
Modified: llvm/branches/Apple/Zoidberg/lib/Analysis/BasicAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Zoidberg/lib/Analysis/BasicAliasAnalysis.cpp?rev=89739&r1=89738&r2=89739&view=diff
==============================================================================
--- llvm/branches/Apple/Zoidberg/lib/Analysis/BasicAliasAnalysis.cpp (original)
+++ llvm/branches/Apple/Zoidberg/lib/Analysis/BasicAliasAnalysis.cpp Mon Nov 23 23:32:21 2009
@@ -79,7 +79,12 @@
static bool isNonEscapingLocalObject(const Value *V) {
// If this is a local allocation, check to see if it escapes.
if (isa<AllocaInst>(V) || isNoAliasCall(V))
- return !PointerMayBeCaptured(V, false);
+ // Set StoreCaptures to True so that we can assume in our callers that the
+ // pointer is not the result of a load instruction. Currently
+ // PointerMayBeCaptured doesn't have any special analysis for the
+ // StoreCaptures=false case; if it did, our callers could be refined to be
+ // more precise.
+ return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true);
// If this is an argument that corresponds to a byval or noalias argument,
// then it has not escaped before entering the function. Check if it escapes
@@ -89,7 +94,7 @@
// Don't bother analyzing arguments already known not to escape.
if (A->hasNoCaptureAttr())
return true;
- return !PointerMayBeCaptured(V, false);
+ return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true);
}
return false;
}
@@ -683,15 +688,19 @@
(V2Size != ~0U && isObjectSmallerThan(O1, V2Size, *TD)))
return NoAlias;
- // If one pointer is the result of a call/invoke and the other is a
+ // If one pointer is the result of a call/invoke or load and the other is a
// non-escaping local object, then we know the object couldn't escape to a
- // point where the call could return it.
- if ((isa<CallInst>(O1) || isa<InvokeInst>(O1)) &&
- isNonEscapingLocalObject(O2) && O1 != O2)
- return NoAlias;
- if ((isa<CallInst>(O2) || isa<InvokeInst>(O2)) &&
- isNonEscapingLocalObject(O1) && O1 != O2)
- return NoAlias;
+ // point where the call could return it. The load case works because
+ // isNonEscapingLocalObject considers all stores to be escapes (it
+ // passes true for the StoreCaptures argument to PointerMayBeCaptured).
+ if (O1 != O2) {
+ if ((isa<CallInst>(O1) || isa<InvokeInst>(O1) || isa<LoadInst>(O1)) &&
+ isNonEscapingLocalObject(O2))
+ return NoAlias;
+ if ((isa<CallInst>(O2) || isa<InvokeInst>(O2) || isa<LoadInst>(O2)) &&
+ isNonEscapingLocalObject(O1))
+ return NoAlias;
+ }
if (!isa<GEPOperator>(V1) && isa<GEPOperator>(V2)) {
std::swap(V1, V2);
Modified: llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp?rev=89739&r1=89738&r2=89739&view=diff
==============================================================================
--- llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp (original)
+++ llvm/branches/Apple/Zoidberg/lib/Analysis/CaptureTracking.cpp Mon Nov 23 23:32:21 2009
@@ -19,6 +19,7 @@
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Instructions.h"
#include "llvm/Value.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/CallSite.h"
@@ -28,8 +29,11 @@
/// by the enclosing function (which is required to exist). This routine can
/// be expensive, so consider caching the results. The boolean ReturnCaptures
/// specifies whether returning the value (or part of it) from the function
+/// counts as capturing it or not. The boolean StoreCaptures specified whether
+/// storing the value (or part of it) into memory anywhere automatically
/// counts as capturing it or not.
-bool llvm::PointerMayBeCaptured(const Value *V, bool ReturnCaptures) {
+bool llvm::PointerMayBeCaptured(const Value *V,
+ bool ReturnCaptures, bool StoreCaptures) {
assert(isa<PointerType>(V->getType()) && "Capture is for pointers only!");
SmallVector<Use*, 16> Worklist;
SmallSet<Use*, 16> Visited;
@@ -53,8 +57,7 @@
// Not captured if the callee is readonly, doesn't return a copy through
// its return value and doesn't unwind (a readonly function can leak bits
// by throwing an exception or not depending on the input value).
- if (CS.onlyReadsMemory() && CS.doesNotThrow() &&
- I->getType() == Type::getVoidTy(V->getContext()))
+ if (CS.onlyReadsMemory() && CS.doesNotThrow() && I->getType()->isVoidTy())
break;
// Not captured if only passed via 'nocapture' arguments. Note that
@@ -82,7 +85,11 @@
break;
case Instruction::Store:
if (V == I->getOperand(0))
- // Stored the pointer - it may be captured.
+ // Stored the pointer - conservatively assume it may be captured.
+ // TODO: If StoreCaptures is not true, we could do Fancy analysis
+ // to determine whether this store is not actually an escape point.
+ // In that case, BasicAliasAnalysis should be updated as well to
+ // take advantage of this.
return true;
// Storing to the pointee does not cause the pointer to be captured.
break;
@@ -98,6 +105,18 @@
Worklist.push_back(U);
}
break;
+ case Instruction::ICmp:
+ // Don't count comparisons of a no-alias return value against null as
+ // captures. This allows us to ignore comparisons of malloc results
+ // with null, for example.
+ if (isNoAliasCall(V->stripPointerCasts()))
+ if (ConstantPointerNull *CPN =
+ dyn_cast<ConstantPointerNull>(I->getOperand(1)))
+ if (CPN->getType()->getAddressSpace() == 0)
+ break;
+ // Otherwise, be conservative. There are crazy ways to capture pointers
+ // using comparisons.
+ return true;
default:
// Something else - be conservative and say it is captured.
return true;
Modified: llvm/branches/Apple/Zoidberg/lib/Transforms/IPO/FunctionAttrs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Zoidberg/lib/Transforms/IPO/FunctionAttrs.cpp?rev=89739&r1=89738&r2=89739&view=diff
==============================================================================
--- llvm/branches/Apple/Zoidberg/lib/Transforms/IPO/FunctionAttrs.cpp (original)
+++ llvm/branches/Apple/Zoidberg/lib/Transforms/IPO/FunctionAttrs.cpp Mon Nov 23 23:32:21 2009
@@ -212,7 +212,7 @@
for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); A!=E; ++A)
if (isa<PointerType>(A->getType()) && !A->hasNoCaptureAttr() &&
- !PointerMayBeCaptured(A, true)) {
+ !PointerMayBeCaptured(A, true, /*StoreCaptures=*/false)) {
A->addAttr(Attribute::NoCapture);
++NumNoCapture;
Changed = true;
@@ -280,7 +280,7 @@
return false; // Did not come from an allocation.
}
- if (PointerMayBeCaptured(RetVal, false))
+ if (PointerMayBeCaptured(RetVal, false, /*StoreCaptures=*/false))
return false;
}
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