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Don't attempt to simplify an non-affine IV expression if it can't
be simplified to a loop-invariant value. This fixes PR4315. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72798 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -465,17 +465,6 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType,
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// Compute the final addrec to expand into code.
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SCEVHandle AR = IU->getReplacementExpr(*UI);
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// FIXME: It is an extremely bad idea to indvar substitute anything more
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// complex than affine induction variables. Doing so will put expensive
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// polynomial evaluations inside of the loop, and the str reduction pass
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// currently can only reduce affine polynomials. For now just disable
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// indvar subst on anything more complex than an affine addrec, unless
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// it can be expanded to a trivial value.
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if (!Stride->isLoopInvariant(L) &&
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!isa<SCEVConstant>(AR) &&
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L->contains(User->getParent()))
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continue;
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Value *NewVal = 0;
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if (AR->isLoopInvariant(L)) {
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BasicBlock::iterator I = Rewriter.getInsertionPoint();
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@ -487,6 +476,15 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType,
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Rewriter.setInsertionPoint(I);
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++NumReplaced;
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} else {
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// FIXME: It is an extremely bad idea to indvar substitute anything more
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// complex than affine induction variables. Doing so will put expensive
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// polynomial evaluations inside of the loop, and the str reduction pass
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// currently can only reduce affine polynomials. For now just disable
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// indvar subst on anything more complex than an affine addrec, unless
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// it can be expanded to a trivial value.
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if (!Stride->isLoopInvariant(L))
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continue;
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const Type *IVTy = Offset->getType();
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const Type *UseTy = Op->getType();
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@ -520,7 +518,7 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType,
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// induction variable, still in the canonical induction variable's
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// type, so that all expanded arithmetic is done in the same type.
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SCEVHandle NewAR = SE->getAddRecExpr(SE->getIntegerSCEV(0, LargestType),
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PromotedStride, L);
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PromotedStride, L);
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// Add the PromotedOffset as a separate step, because it may not be
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// loop-invariant.
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NewAR = SE->getAddExpr(NewAR, PromotedOffset);
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43
test/Transforms/IndVarSimplify/variable-stride-ivs-1.ll
Normal file
43
test/Transforms/IndVarSimplify/variable-stride-ivs-1.ll
Normal file
@ -0,0 +1,43 @@
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; RUN: llvm-as < %s | opt -indvars
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; PR4315
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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-f80:128:128"
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target triple = "x86_64-undermydesk-freebsd8.0"
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%struct.mbuf = type <{ %struct.mbuf*, i8*, i32, i8, i8, i8, i8 }>
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define i32 @crash(%struct.mbuf* %m) nounwind {
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entry:
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br label %for.cond
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for.cond: ; preds = %if.end, %entry
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%i.0 = phi i32 [ 0, %entry ], [ %inc, %if.end ] ; <i32> [#uses=3]
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%chksum.0 = phi i8 [ 0, %entry ], [ %conv3, %if.end ] ; <i8> [#uses=3]
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%cmp = icmp slt i32 %i.0, 1 ; <i1> [#uses=1]
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br i1 %cmp, label %for.body, label %do.body
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for.body: ; preds = %for.cond
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br i1 undef, label %if.end, label %do.body
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if.end: ; preds = %for.body
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%i.02 = trunc i32 %i.0 to i8 ; <i8> [#uses=1]
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%conv3 = add i8 %chksum.0, %i.02 ; <i8> [#uses=1]
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%inc = add i32 %i.0, 1 ; <i32> [#uses=1]
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br label %for.cond
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do.body: ; preds = %do.cond, %for.body, %for.cond
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%chksum.2 = phi i8 [ undef, %do.cond ], [ %chksum.0, %for.body ], [ %chksum.0, %for.cond ] ; <i8> [#uses=1]
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br i1 undef, label %do.cond, label %bb.nph
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bb.nph: ; preds = %do.body
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br label %while.body
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while.body: ; preds = %while.body, %bb.nph
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%chksum.13 = phi i8 [ undef, %while.body ], [ %chksum.2, %bb.nph ] ; <i8> [#uses=0]
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br i1 undef, label %do.cond, label %while.body
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do.cond: ; preds = %while.body, %do.body
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br i1 false, label %do.end, label %do.body
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do.end: ; preds = %do.cond
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ret i32 0
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}
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