implement a FIXME: limit the depth that DecomposeGEPExpression goes the same

way that getUnderlyingObject does it. 

This fixes the 'DecomposeGEPExpression and getUnderlyingObject disagree!' 
assertion on sqlite3.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90038 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-11-28 15:12:41 +00:00
parent af7a28939e
commit ab9530ee5d
2 changed files with 26 additions and 4 deletions

View File

@ -1028,9 +1028,11 @@ static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
const Value *llvm::DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
SmallVectorImpl<std::pair<const Value*, int64_t> > &VarIndices,
const TargetData *TD) {
// FIXME: Should limit depth like getUnderlyingObject?
// Limit recursion depth to limit compile time in crazy cases.
unsigned MaxLookup = 6;
BaseOffs = 0;
while (1) {
do {
// See if this is a bitcast or GEP.
const Operator *Op = dyn_cast<Operator>(V);
if (Op == 0) {
@ -1128,7 +1130,10 @@ const Value *llvm::DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
// Analyze the base pointer next.
V = GEPOp->getOperand(0);
}
} while (--MaxLookup);
// If the chain of expressions is too deep, just return early.
return V;
}

View File

@ -1,4 +1,4 @@
; RUN: opt < %s -dse | llvm-dis
; RUN: opt < %s -dse -S
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin10.0"
@ -24,3 +24,20 @@ bb: ; preds = %bb, %entry
%2 = tail call signext i8 @foo(i8 signext undef, i8 signext 1) nounwind ; <i8> [#uses=1]
br label %bb
}
define fastcc i32 @test2() nounwind ssp {
bb14: ; preds = %bb4
%0 = bitcast i8* undef to i8** ; <i8**> [#uses=1]
%1 = getelementptr inbounds i8** %0, i64 undef ; <i8**> [#uses=1]
%2 = bitcast i8** %1 to i16* ; <i16*> [#uses=2]
%3 = getelementptr inbounds i16* %2, i64 undef ; <i16*> [#uses=1]
%4 = bitcast i16* %3 to i8* ; <i8*> [#uses=1]
%5 = getelementptr inbounds i8* %4, i64 undef ; <i8*> [#uses=1]
%6 = getelementptr inbounds i16* %2, i64 undef ; <i16*> [#uses=1]
store i16 undef, i16* %6, align 2
%7 = getelementptr inbounds i8* %5, i64 undef ; <i8*> [#uses=1]
call void @llvm.memcpy.i64(i8* %7, i8* undef, i64 undef, i32 1) nounwind
unreachable
}
declare void @llvm.memcpy.i64(i8* nocapture, i8* nocapture, i64, i32) nounwind