From: Dan Gohman Date: Wed, 3 Jun 2009 19:11:31 +0000 (+0000) Subject: Don't attempt to simplify an non-affine IV expression if it can't X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=68c9344056e714336a522148e0e468f35035c650;p=oota-llvm.git 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 --- diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index ca7aa7bd30d..af61eae16f8 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -465,17 +465,6 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType, // Compute the final addrec to expand into code. SCEVHandle AR = IU->getReplacementExpr(*UI); - // FIXME: It is an extremely bad idea to indvar substitute anything more - // complex than affine induction variables. Doing so will put expensive - // polynomial evaluations inside of the loop, and the str reduction pass - // currently can only reduce affine polynomials. For now just disable - // indvar subst on anything more complex than an affine addrec, unless - // it can be expanded to a trivial value. - if (!Stride->isLoopInvariant(L) && - !isa(AR) && - L->contains(User->getParent())) - continue; - Value *NewVal = 0; if (AR->isLoopInvariant(L)) { BasicBlock::iterator I = Rewriter.getInsertionPoint(); @@ -487,6 +476,15 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType, Rewriter.setInsertionPoint(I); ++NumReplaced; } else { + // FIXME: It is an extremely bad idea to indvar substitute anything more + // complex than affine induction variables. Doing so will put expensive + // polynomial evaluations inside of the loop, and the str reduction pass + // currently can only reduce affine polynomials. For now just disable + // indvar subst on anything more complex than an affine addrec, unless + // it can be expanded to a trivial value. + if (!Stride->isLoopInvariant(L)) + continue; + const Type *IVTy = Offset->getType(); const Type *UseTy = Op->getType(); @@ -520,7 +518,7 @@ void IndVarSimplify::RewriteIVExpressions(Loop *L, const Type *LargestType, // induction variable, still in the canonical induction variable's // type, so that all expanded arithmetic is done in the same type. SCEVHandle NewAR = SE->getAddRecExpr(SE->getIntegerSCEV(0, LargestType), - PromotedStride, L); + PromotedStride, L); // Add the PromotedOffset as a separate step, because it may not be // loop-invariant. NewAR = SE->getAddExpr(NewAR, PromotedOffset); diff --git a/test/Transforms/IndVarSimplify/variable-stride-ivs-0.ll b/test/Transforms/IndVarSimplify/variable-stride-ivs-0.ll new file mode 100644 index 00000000000..759ba8e177b --- /dev/null +++ b/test/Transforms/IndVarSimplify/variable-stride-ivs-0.ll @@ -0,0 +1,43 @@ +; RUN: llvm-as < %s | opt -indvars -instcombine | llvm-dis | \ +; RUN: grep {store i32 0} +; Test that -indvars can reduce variable stride IVs. If it can reduce variable +; stride iv's, it will make %iv. and %m.0.0 isomorphic to each other without +; cycles, allowing the tmp.21 subtraction to be eliminated. +; END. + +define void @vnum_test8(i32* %data) { +entry: + %tmp.1 = getelementptr i32* %data, i32 3 ; [#uses=1] + %tmp.2 = load i32* %tmp.1 ; [#uses=2] + %tmp.4 = getelementptr i32* %data, i32 4 ; [#uses=1] + %tmp.5 = load i32* %tmp.4 ; [#uses=2] + %tmp.8 = getelementptr i32* %data, i32 2 ; [#uses=1] + %tmp.9 = load i32* %tmp.8 ; [#uses=3] + %tmp.125 = icmp sgt i32 %tmp.2, 0 ; [#uses=1] + br i1 %tmp.125, label %no_exit.preheader, label %return + +no_exit.preheader: ; preds = %entry + %tmp.16 = getelementptr i32* %data, i32 %tmp.9 ; [#uses=1] + br label %no_exit + +no_exit: ; preds = %no_exit, %no_exit.preheader + %iv.ui = phi i32 [ 0, %no_exit.preheader ], [ %iv..inc.ui, %no_exit ] ; [#uses=1] + %iv. = phi i32 [ %tmp.5, %no_exit.preheader ], [ %iv..inc, %no_exit ] ; [#uses=2] + %m.0.0 = phi i32 [ %tmp.5, %no_exit.preheader ], [ %tmp.24, %no_exit ] ; [#uses=2] + store i32 2, i32* %tmp.16 + %tmp.21 = sub i32 %m.0.0, %iv. ; [#uses=1] + store i32 %tmp.21, i32* %data + %tmp.24 = add i32 %m.0.0, %tmp.9 ; [#uses=1] + %iv..inc = add i32 %tmp.9, %iv. ; [#uses=1] + %iv..inc.ui = add i32 %iv.ui, 1 ; [#uses=2] + %iv..inc1 = bitcast i32 %iv..inc.ui to i32 ; [#uses=1] + %tmp.12 = icmp slt i32 %iv..inc1, %tmp.2 ; [#uses=1] + br i1 %tmp.12, label %no_exit, label %return.loopexit + +return.loopexit: ; preds = %no_exit + br label %return + +return: ; preds = %return.loopexit, %entry + ret void +} + diff --git a/test/Transforms/IndVarSimplify/variable-stride-ivs-1.ll b/test/Transforms/IndVarSimplify/variable-stride-ivs-1.ll new file mode 100644 index 00000000000..075e899cd96 --- /dev/null +++ b/test/Transforms/IndVarSimplify/variable-stride-ivs-1.ll @@ -0,0 +1,43 @@ +; RUN: llvm-as < %s | opt -indvars +; PR4315 + +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" +target triple = "x86_64-undermydesk-freebsd8.0" + %struct.mbuf = type <{ %struct.mbuf*, i8*, i32, i8, i8, i8, i8 }> + +define i32 @crash(%struct.mbuf* %m) nounwind { +entry: + br label %for.cond + +for.cond: ; preds = %if.end, %entry + %i.0 = phi i32 [ 0, %entry ], [ %inc, %if.end ] ; [#uses=3] + %chksum.0 = phi i8 [ 0, %entry ], [ %conv3, %if.end ] ; [#uses=3] + %cmp = icmp slt i32 %i.0, 1 ; [#uses=1] + br i1 %cmp, label %for.body, label %do.body + +for.body: ; preds = %for.cond + br i1 undef, label %if.end, label %do.body + +if.end: ; preds = %for.body + %i.02 = trunc i32 %i.0 to i8 ; [#uses=1] + %conv3 = add i8 %chksum.0, %i.02 ; [#uses=1] + %inc = add i32 %i.0, 1 ; [#uses=1] + br label %for.cond + +do.body: ; preds = %do.cond, %for.body, %for.cond + %chksum.2 = phi i8 [ undef, %do.cond ], [ %chksum.0, %for.body ], [ %chksum.0, %for.cond ] ; [#uses=1] + br i1 undef, label %do.cond, label %bb.nph + +bb.nph: ; preds = %do.body + br label %while.body + +while.body: ; preds = %while.body, %bb.nph + %chksum.13 = phi i8 [ undef, %while.body ], [ %chksum.2, %bb.nph ] ; [#uses=0] + br i1 undef, label %do.cond, label %while.body + +do.cond: ; preds = %while.body, %do.body + br i1 false, label %do.end, label %do.body + +do.end: ; preds = %do.cond + ret i32 0 +} diff --git a/test/Transforms/IndVarSimplify/variable-stride-ivs.ll b/test/Transforms/IndVarSimplify/variable-stride-ivs.ll deleted file mode 100644 index 759ba8e177b..00000000000 --- a/test/Transforms/IndVarSimplify/variable-stride-ivs.ll +++ /dev/null @@ -1,43 +0,0 @@ -; RUN: llvm-as < %s | opt -indvars -instcombine | llvm-dis | \ -; RUN: grep {store i32 0} -; Test that -indvars can reduce variable stride IVs. If it can reduce variable -; stride iv's, it will make %iv. and %m.0.0 isomorphic to each other without -; cycles, allowing the tmp.21 subtraction to be eliminated. -; END. - -define void @vnum_test8(i32* %data) { -entry: - %tmp.1 = getelementptr i32* %data, i32 3 ; [#uses=1] - %tmp.2 = load i32* %tmp.1 ; [#uses=2] - %tmp.4 = getelementptr i32* %data, i32 4 ; [#uses=1] - %tmp.5 = load i32* %tmp.4 ; [#uses=2] - %tmp.8 = getelementptr i32* %data, i32 2 ; [#uses=1] - %tmp.9 = load i32* %tmp.8 ; [#uses=3] - %tmp.125 = icmp sgt i32 %tmp.2, 0 ; [#uses=1] - br i1 %tmp.125, label %no_exit.preheader, label %return - -no_exit.preheader: ; preds = %entry - %tmp.16 = getelementptr i32* %data, i32 %tmp.9 ; [#uses=1] - br label %no_exit - -no_exit: ; preds = %no_exit, %no_exit.preheader - %iv.ui = phi i32 [ 0, %no_exit.preheader ], [ %iv..inc.ui, %no_exit ] ; [#uses=1] - %iv. = phi i32 [ %tmp.5, %no_exit.preheader ], [ %iv..inc, %no_exit ] ; [#uses=2] - %m.0.0 = phi i32 [ %tmp.5, %no_exit.preheader ], [ %tmp.24, %no_exit ] ; [#uses=2] - store i32 2, i32* %tmp.16 - %tmp.21 = sub i32 %m.0.0, %iv. ; [#uses=1] - store i32 %tmp.21, i32* %data - %tmp.24 = add i32 %m.0.0, %tmp.9 ; [#uses=1] - %iv..inc = add i32 %tmp.9, %iv. ; [#uses=1] - %iv..inc.ui = add i32 %iv.ui, 1 ; [#uses=2] - %iv..inc1 = bitcast i32 %iv..inc.ui to i32 ; [#uses=1] - %tmp.12 = icmp slt i32 %iv..inc1, %tmp.2 ; [#uses=1] - br i1 %tmp.12, label %no_exit, label %return.loopexit - -return.loopexit: ; preds = %no_exit - br label %return - -return: ; preds = %return.loopexit, %entry - ret void -} -