Add a new attribute, 'noduplicate'. If a function contains a noduplicate call, the call cannot be duplicated - Jump threading, loop unrolling, loop unswitching, and loop rotation are inhibited if they would duplicate the call.
Similarly inlining of the function is inhibited, if that would duplicate the call (in particular inlining is still allowed when there is only one callsite and the function has internal linkage).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170704 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index f88cabb..de89fea 100644
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -54,6 +54,8 @@
bool IsRecursiveCall;
bool ExposesReturnsTwice;
bool HasDynamicAlloca;
+ bool ContainsNoDuplicateCall;
+
/// Number of bytes allocated statically by the callee.
uint64_t AllocatedSize;
unsigned NumInstructions, NumVectorInstructions;
@@ -128,8 +130,8 @@
CallAnalyzer(const DataLayout *TD, Function &Callee, int Threshold)
: TD(TD), F(Callee), Threshold(Threshold), Cost(0),
IsCallerRecursive(false), IsRecursiveCall(false),
- ExposesReturnsTwice(false), HasDynamicAlloca(false), AllocatedSize(0),
- NumInstructions(0), NumVectorInstructions(0),
+ ExposesReturnsTwice(false), HasDynamicAlloca(false), ContainsNoDuplicateCall(false),
+ AllocatedSize(0), NumInstructions(0), NumVectorInstructions(0),
FiftyPercentVectorBonus(0), TenPercentVectorBonus(0), VectorBonus(0),
NumConstantArgs(0), NumConstantOffsetPtrArgs(0), NumAllocaArgs(0),
NumConstantPtrCmps(0), NumConstantPtrDiffs(0),
@@ -615,6 +617,9 @@
ExposesReturnsTwice = true;
return false;
}
+ if (CS.isCall() &&
+ cast<CallInst>(CS.getInstruction())->hasFnAttr(Attribute::NoDuplicate))
+ ContainsNoDuplicateCall = true;
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
switch (II->getIntrinsicID()) {
@@ -842,7 +847,9 @@
// If there is only one call of the function, and it has internal linkage,
// the cost of inlining it drops dramatically.
- if (F.hasLocalLinkage() && F.hasOneUse() && &F == CS.getCalledFunction())
+ bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() &&
+ &F == CS.getCalledFunction();
+ if (OnlyOneCallAndLocalLinkage)
Cost += InlineConstants::LastCallToStaticBonus;
// If the instruction after the call, or if the normal destination of the
@@ -1008,6 +1015,12 @@
}
}
+ // If this is a noduplicate call, we can still inline as long as
+ // inlining this would cause the removal of the caller (so the instruction
+ // is not actually duplicated, just moved).
+ if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
+ return false;
+
Threshold += VectorBonus;
return Cost < Threshold;
@@ -1025,6 +1038,7 @@
DEBUG_PRINT_STAT(NumInstructionsSimplified);
DEBUG_PRINT_STAT(SROACostSavings);
DEBUG_PRINT_STAT(SROACostSavingsLost);
+ DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
#undef DEBUG_PRINT_STAT
}
#endif