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Improve the safety of my globalopt enhancement by ensuring that the bitcast

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of the stored value to the new store type is always.  Also, add a testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123563 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2011-01-16 04:33:33 +00:00
parent 156eb0a569
commit 66f708f7e5
2 changed files with 81 additions and 12 deletions
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34
lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -2358,21 +2358,31 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal,
const Type *NewTy=cast<PointerType>(Ptr->getType())->getElementType();
// A bitcast'd pointer implicitly points to the first field of a
// struct. Insert implicity "gep @x, 0, 0, ..." until we get down
// to the first concrete member.
// FIXME: This could be extended to work for arrays as well.
while (const StructType *STy = dyn_cast<StructType>(NewTy)) {
NewTy = STy->getTypeAtIndex(0U);
// In order to push the bitcast onto the stored value, a bitcast
// from NewTy to Val's type must be legal. If it's not, we can try
// introspecting NewTy to find a legal conversion.
while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) {
// If NewTy is a struct, we can convert the pointer to the struct
// into a pointer to its first member.
// FIXME: This could be extended to support arrays as well.
if (const StructType *STy = dyn_cast<StructType>(NewTy)) {
NewTy = STy->getTypeAtIndex(0U);
const IntegerType *IdxTy =IntegerType::get(NewTy->getContext(), 32);
Constant *IdxZero = ConstantInt::get(IdxTy, 0, false);
Constant * const IdxList[] = {IdxZero, IdxZero};
Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList, 2);
const IntegerType *IdxTy =IntegerType::get(NewTy->getContext(), 32);
Constant *IdxZero = ConstantInt::get(IdxTy, 0, false);
Constant * const IdxList[] = {IdxZero, IdxZero};
Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList, 2);
// If we can't improve the situation by introspecting NewTy,
// we have to give up.
} else {
return 0;
}
}
if (!isa<PointerType>(NewTy)) return false;
// If we found compatible types, go ahead and push the bitcast
// onto the stored value.
Val = ConstantExpr::getBitCast(Val, NewTy);
}

59
test/Transforms/GlobalOpt/static-ctor-bitcast.ll Normal file
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@ -0,0 +1,59 @@
; RUN: opt -S -globalopt < %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-darwin10.0.0"
%0 = type { i8*, i8* }
%1 = type { i8*, i8*, i32, i32, i8*, i64 }
%2 = type { i32, void ()* }
%struct.A = type { i32 }
%struct.B = type { i32 (...)**, i8*, [4 x i8] }
@y = global i8 0, align 1
@x = global %struct.B zeroinitializer, align 8
@_ZTV1B = weak_odr unnamed_addr constant [3 x i8*] [i8* inttoptr (i64 16 to i8*), i8* null, i8* bitcast (%1* @_ZTI1B to i8*)]
@_ZTVN10__cxxabiv121__vmi_class_type_infoE = external global i8*
@_ZTS1B = weak_odr constant [3 x i8] c"1B\00"
@_ZTVN10__cxxabiv117__class_type_infoE = external global i8*
@_ZTS1A = weak_odr constant [3 x i8] c"1A\00"
@_ZTI1A = weak_odr unnamed_addr constant %0 { i8* bitcast (i8** getelementptr inbounds (i8** @_ZTVN10__cxxabiv117__class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8]* @_ZTS1A, i32 0, i32 0) }
@_ZTI1B = weak_odr unnamed_addr constant %1 { i8* bitcast (i8** getelementptr inbounds (i8** @_ZTVN10__cxxabiv121__vmi_class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([3 x i8]* @_ZTS1B, i32 0, i32 0), i32 0, i32 1, i8* bitcast (%0* @_ZTI1A to i8*), i64 -6141 }
@_ZTT1B = weak_odr unnamed_addr constant [1 x i8*] [i8* bitcast (i8** getelementptr inbounds ([3 x i8*]* @_ZTV1B, i64 1, i64 0) to i8*)]
@llvm.global_ctors = appending global [1 x %2] [%2 { i32 65535, void ()* @_GLOBAL__I_a }]
; CHECK-NOT: __cxx_global_var_init
define internal void @__cxx_global_var_init() section "__TEXT,__StaticInit,regular,pure_instructions" {
entry:
call void @_ZN1BC1Ev(%struct.B* @x)
ret void
}
; CHECK-NOT: _ZN1BC1Ev
define linkonce_odr unnamed_addr void @_ZN1BC1Ev(%struct.B* %this) inlinehint ssp align 2 {
entry:
%0 = bitcast %struct.B* %this to i8*
%1 = getelementptr inbounds i8* %0, i64 16
%2 = bitcast i8* %1 to %struct.A*
call void @_ZN1AC2Ev(%struct.A* %2)
%3 = bitcast %struct.B* %this to i8***
store i8** getelementptr inbounds ([3 x i8*]* @_ZTV1B, i64 1, i64 0), i8*** %3
ret void
}
; CHECK-NOT: _ZN1AC2Ev
define linkonce_odr unnamed_addr void @_ZN1AC2Ev(%struct.A* %this) nounwind ssp align 2 {
entry:
%0 = ptrtoint %struct.A* %this to i64
%sub = sub i64 %0, ptrtoint (%struct.B* @x to i64)
%div = udiv i64 %sub, 8
%conv = trunc i64 %div to i8
store i8 %conv, i8* @y, align 1
ret void
}
; CHECK-NOT: _GLOBAL__I_a
define internal void @_GLOBAL__I_a() section "__TEXT,__StaticInit,regular,pure_instructions" {
entry:
call void @__cxx_global_var_init()
ret void
}