[llvm-commits] [llvm] r41046 - /llvm/trunk/lib/VMCore/ConstantFold.cpp
Chris Lattner
sabre at nondot.org
Mon Aug 13 10:09:08 PDT 2007
Author: lattner
Date: Mon Aug 13 12:09:08 2007
New Revision: 41046
URL: http://llvm.org/viewvc/llvm-project?rev=41046&view=rev
Log:
Constant fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
Into: inttoptr (i64 0 to i8*) -> null
This occurs in the example in PR1602. With this fixed, we now compile
the example in PR1602 into fully "devirtualized" code:
define void @_Z1g1S(%struct.S* noalias %s) {
entry: %tmp131415 = getelementptr %struct.S* %s, i32 0, i32 0 ; <i32 (...)***> [#uses=1] %tmp16 = load i32 (...)*** %tmp131415, align 4 ; <i32 (...)**> [#uses=1]
%tmp26277 = load i32 (...)** %tmp16 ; <i32 (...)*> [#uses=1]
%tmp2829 = bitcast i32 (...)* %tmp26277 to void (%struct.S*)* ; <void (%struct.S*)*> [#uses=1]
tail call void %tmp2829( %struct.S* %s )
ret void
}
This still has the vtable dispatch (as required) but does not have any pointer
to method cruft left.
Modified:
llvm/trunk/lib/VMCore/ConstantFold.cpp
Modified: llvm/trunk/lib/VMCore/ConstantFold.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/ConstantFold.cpp?rev=41046&r1=41045&r2=41046&view=diff
==============================================================================
--- llvm/trunk/lib/VMCore/ConstantFold.cpp (original)
+++ llvm/trunk/lib/VMCore/ConstantFold.cpp Mon Aug 13 12:09:08 2007
@@ -1427,7 +1427,7 @@
// long 0, long 0)
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
//
- if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue())
+ if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) {
if (const PointerType *SPT =
dyn_cast<PointerType>(CE->getOperand(0)->getType()))
if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
@@ -1436,6 +1436,28 @@
if (CAT->getElementType() == SAT->getElementType())
return ConstantExpr::getGetElementPtr(
(Constant*)CE->getOperand(0), Idxs, NumIdx);
+ }
+
+ // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
+ // Into: inttoptr (i64 0 to i8*)
+ // This happens with pointers to member functions in C++.
+ if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
+ isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
+ cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) {
+ Constant *Base = CE->getOperand(0);
+ Constant *Offset = Idxs[0];
+
+ // Convert the smaller integer to the larger type.
+ if (Offset->getType()->getPrimitiveSizeInBits() <
+ Base->getType()->getPrimitiveSizeInBits())
+ Offset = ConstantExpr::getSExt(Offset, Base->getType());
+ else if (Base->getType()->getPrimitiveSizeInBits() <
+ Offset->getType()->getPrimitiveSizeInBits())
+ Base = ConstantExpr::getZExt(Base, Base->getType());
+
+ Base = ConstantExpr::getAdd(Base, Offset);
+ return ConstantExpr::getIntToPtr(Base, CE->getType());
+ }
}
return 0;
}
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